Probiotics for treating acute infectious diarrhoea

Stephen J Allen; Elizabeth G Martinez; Germana V Gregorio; Leonila F Dans

doi:10.1002/14651858.CD003048.pub3

. 2010 Nov 10;2010(11):CD003048. doi: 10.1002/14651858.CD003048.pub3

Probiotics for treating acute infectious diarrhoea

Stephen J Allen ^1,^✉, Elizabeth G Martinez ², Germana V Gregorio ², Leonila F Dans ³

Editor: Cochrane Infectious Diseases Group

PMCID: PMC6532699 PMID: 21069673

Abstract

Background

Probiotics may offer a safe intervention in acute infectious diarrhoea to reduce the duration and severity of the illness.

Objectives

To assess the effects of probiotics in proven or presumed acute infectious diarrhoea.

Search methods

We searched the Cochrane Infectious Diseases Group's trials register (July 2010), the Cochrane Controlled Trials Register (The Cochrane Library Issue 2, 2010), MEDLINE (1966 to July 2010), EMBASE (1988 to July 2010), and reference lists from studies and reviews. We also contacted organizations and individuals working in the field, and pharmaceutical companies manufacturing probiotic agents.

Selection criteria

Randomized and quasi‐randomized controlled trials comparing a specified probiotic agent with a placebo or no probiotic in people with acute diarrhoea that is proven or presumed to be caused by an infectious agent.

Data collection and analysis

Two reviewers independently assessed the methodological quality of the trial and extracted data. Primary outcomes were the mean duration of diarrhoea, stool frequency on day 2 after intervention and ongoing diarrhoea on day 4. A random‐effects model was used.

Main results

Sixty‐three studies met the inclusion criteria with a total of 8014 participants. Of these, 56 trials recruited infants and young children. The trials varied in the definition used for acute diarrhoea and the end of the diarrhoeal illness, as well as in the risk of bias. The trials were undertaken in a wide range of different settings and also varied greatly in organisms tested, dosage, and participants' characteristics. No adverse events were attributed to the probiotic intervention.

Probiotics reduced the duration of diarrhoea, although the size of the effect varied considerably between studies.

The average of the effect was significant for mean duration of diarrhoea (mean difference 24.76 hours; 95% confidence interval 15.9 to 33.6 hours; n=4555, trials=35) diarrhoea lasting ≥4 days (risk ratio 0.41; 0.32 to 0.53; n=2853, trials=29) and stool frequency on day 2 (mean difference 0.80; 0.45 to 1.14; n=2751, trials=20).

The differences in effect size between studies was not explained by study quality, probiotic strain, the number of different strains, the viability of the organisms, dosage of organisms, the causes of diarrhoea, or the severity of the diarrhoea, or whether the studies were done in developed or developing countries.

Authors' conclusions

Used alongside rehydration therapy, probiotics appear to be safe and have clear beneficial effects in shortening the duration and reducing stool frequency in acute infectious diarrhoea. However, more research is needed to guide the use of particular probiotic regimens in specific patient groups.

22 March 2019

Update pending

Authors currently updating

The update is due to be published in 2019.

Plain language summary

Probiotics for treating acute infectious diarrhoea

Episodes of acute infectious diarrhoea remain a major disease burden throughout the world, especially in developing countries. They are due to infection by many different organisms. Most episodes are self‐limiting and usually investigations are not done to identify the infectious agent. The main risk to health is dehydration and management aims to improve and maintain hydration status. However, rehydration fluids do not reduce the stool volume or shorten the episode of diarrhoea. Probiotics are "friendly" bacteria that improve health and are not harmful in themselves. A number of randomized controlled trials have been done to see whether probiotics are beneficial in acute infectious diarrhoea. We have searched for as many of these trials as possible and collected together the data in a systematic way to try to discover whether or not probiotics are beneficial in acute diarrhoea. We identified 63 trials, which included a total of 8014 people ‐ mainly infants and children. Probiotics were not associated with any adverse effects. Nearly all studies reported a shortened duration of diarrhoea and reduced stool frequency in people who received probiotics compared to the controls. Overall, probiotics reduced the duration of diarrhoea by around 25 hours, the risk of diarrhoea lasting four or more days by 59% and resulted in about one fewer diarrhoeal stool on day 2 after the intervention. However, there was very marked variability in the study findings and so these estimates are approximate. We concluded that these results were very encouraging but more research is needed to identify exactly which probiotics should be used for which groups of people, and also to assess the cost effectiveness of this treatment.

Background

Definition

Diarrhoea is defined by the World Health Organization (WHO) as three or more loose or watery stools (taking the shape of the container) in a 24‐hour period. Diarrhoea is acute if the illness started less than 14 days previously, and persistent if the episode has lasted 14 days or more (Anonymous 1988). Normal infants who are exclusively breast fed may pass loose, "pasty" stools frequently. In this group the definition is usually based on what the mother considers to be diarrhoea (WHO 1990). Infectious diarrhoea is an episode of diarrhoea that is caused by an infectious agent.

Incidence and disease burden

Infectious diarrhoea occurs much more commonly in developing countries than industrialized countries (Guerrant 1990). Attack rates in developing countries are typically six to 12 episodes per child per year, compared with two in the USA (Savarino 1993). In a systematic analysis of population health data available for 2001, diarrhoeal diseases accounted for 1.78 million deaths (3.7% of total deaths) in low‐ and middle‐income countries (Lopez 2006). Most of these deaths occur in children under five years of age. Although 50% or more children with diarrhoea receive oral rehydration therapy and continued feeding in only six of 60 priority countries, and only seven countries include zinc in diarrhoeal management (Bryce 2006), diarrhoeal deaths have reduced in this age group. However, diarrhoea still accounted for about 1.6 million deaths in 2001 (15% of all deaths in the under fives; Lopez 2006). In industrialized countries deaths from infectious diarrhoea occur mainly in the elderly (Savarino 1993).

Causes

More than 20 viruses, bacteria and parasites are associated with acute diarrhoea (Gadewar 2005). Worldwide, rotavirus is the most common cause of severe diarrhoea and diarrhoea mortality in children (Cunliffe 1998). Other important viral pathogens are astrovirus, human caliciviruses (norovirus and sapovirus) and enteric adenoviruses. Important bacterial pathogens are diarrheogenic Escherichia coli, Salmonella, Shigella, Yersinia, Campylobacter, and Vibrio cholerae. The main parasitic causes of diarrhoea are Cryptosporidium and Giardia (reviewed by O'Ryan 2005). An aetiological study of young children attending hospitals in China, India, Mexico, Myanmar, and Pakistan showed that rotavirus, enterotoxigenic E. coli and Shigella spp. were the most commonly isolated pathogens (Huilan 1991). Acute diarrhoea is frequent among travellers, in whom enterotoxigenic E. coli is particularly common (Black 1986). In practice, most episodes of acute diarrhoea that are assumed to be caused by an infectious agent are treated without the causative agent being identified. The major causes of acute infectious diarrhoea differ according to local factors, such as availability of clean water and sanitation. In contrast with acute infectious diarrhoea, infection is likely to be only one of several factors that contribute to the pathogenesis of persistent diarrhoea (Walker‐Smith 1993).

Treatment

The aim of treatment is to prevent or reverse dehydration, shorten the duration of the illness (important for preventing progression to persistent diarrhoea, which is associated with adverse outcomes such as malnutrition), and to reduce the period that a person is infectious. Treatment options available are oral rehydration solution, antibiotics, and gut motility‐suppressing agents such as loperamide, codeine, and probiotics. This review considers the use of probiotics only.

Probiotics

Probiotics have been defined as microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well‐being of the host (Salminen 1999). Although organisms used in clinical trials may not have a proven health benefit for the indication being investigated, we have used the term "probiotic" in this review for simplicity. Fermenting foods to enhance their taste and nutritional value is an ancient and widespread practice. Well‐known probiotics are the lactic acid bacteria and the yeast Saccharomyces (Naidu 1999). The taxonomy of the lactic acid bacteria relied traditionally on their phenotypic characteristics. Modern molecular techniques have shown these to be unreliable, and polyphasic taxonomy using both phenotypical and molecular techniques is now recommended (Klein 1998). Even closely related probiotic strains can have different clinical effects, and the Food and Agricultural Organization (FAO) of the United Nations and WHO expert consultation committee have emphasized that the beneficial effects observed in one strain cannot be assumed to occur in other strains (FAO/WHO 2001). This implies that the reliable identification of organisms at the strain level is necessary for clinical studies.

The rationale for using probiotics in infectious diarrhoea is that they act against enteric pathogens by competing for available nutrients and binding sites, making the gut contents acid, producing a variety of chemicals, and increasing specific and non‐specific immune responses (Gismondo 1999; Goldin 1998; Vanderhoof 1998). No serious adverse effects of probiotics have been suggested in well people, but rarely, infections have been reported in people with impaired immune systems or indwelling catheters (Hata 1988; Piarroux 1999; Salminen 1998; Saxelin 1996; Sussman 1986).

Six systematic reviews of probiotics in acute diarrhoea have been published. Szajewska 2001 included only published, randomized, placebo‐controlled double‐blind studies of acute diarrhoea lasting three or more days in infants and children. A score was used to assess the methodological quality of these trials. The effects of all probiotics and individual strains were analysed. The risk of diarrhoea lasting three or more days was reduced by 0.40 in the probiotic compared with the placebo group (95% confidence interval (CI) 0.28 to 0.57, random‐effects model, eight trials including 731 children), and probiotics reduced the duration of diarrhoea by 18.2 hours (95% CI 9.5 to 26.9 hours, random‐effects model, eight trials including 773 children). The statistically significant heterogeneity in this result was resolved when one study, which employed a mixture of three probiotic organisms, was excluded. Lactobacillus GG was thought to be particularly effective in rotavirus diarrhoea.

A meta‐analysis undertaken by Van Niel 2002 was restricted to adequately randomized and blinded studies of several strains of lactobacilli in children. Children who had received recent antibiotics were excluded from the study. Probiotics reduced the duration of diarrhoea by 0.7 days (95% CI 0.3 to 1.2 days, seven studies including 675 children) and diarrhoea frequency on day 2 by 1.6 (95% CI 0.7 to 2.6, three studies including 122 children). The heterogeneity of results among the studies prevented an analysis of the effects of individual strains of lactobacilli.

Three meta‐analyses have focused on randomized controlled trials of specific probiotics in acute infectious diarrhoea in children. Szajewska 2007a analysed trials of Lactobacillus casei strain GG where a > 80% follow up was achieved. Trial results published as letters to the editor, abstracts, and proceedings from scientific meetings were not included. L.casei GG reduced the duration of diarrhoea by 1.1 days (95% CI 0.3 to 1.9, seven trials, 876 infants) and was particularly effective in rotavirus diarrhoea (duration reduced by 2.1 days, 95% CI 0.6 to 3.6). However, the authors urged caution in the interpretation of the results in view of methodological limitations in the trials and the heterogeneity of the results in the studies. Chmielewska 2008 identified two trials of Lactobacillus reuteri strain ATTCC 55730. This probiotic reduced the duration of diarrhoea by 22 hours (95% CI 6 to 38, 106 participants). In an update of a previous review (Szajewska 2007b), Szajewska 2009 pooled data from seven randomized controlled trials of Saccharomyces boulardii in 944 otherwise healthy children with acute gastroenteritis. The duration of diarrhoea was reduced by 1.08 days (95% CI 0.53 to 1.64) in children who received the yeast compared with the placebo although there was marked heterogeneity in results among the studies.

A recent review concluded that the beneficial effects of probiotics in acute infectious diarrhoea were dependent on the strain of bacteria and the dose (a greater effect with doses >10¹⁰‐10¹¹ colony‐forming units (CFU)/day). They were significant in watery diarrhoea and viral gastroenteritis but absent in invasive bacterial diarrhoea, and were greater when probiotics were administered early in the illness and were more evident in developed countries (Wolvers 2010).

Our review aims to assess the evidence base to inform the use of probiotics in acute infectious diarrhoea. To maximize use of available data, we included participants of all ages, unpublished studies, and non‐blinded (open) studies. We assessed the relevant methodological aspects of trials individually (Juni 1999). These were the generation of allocation sequence, allocation concealment, blinding, and loss to follow up. To maximize the relevance of our findings for clinical practice we included studies in which participants with infectious diarrhoea had received antibiotics prior to recruitment.

For primary outcomes, we chose the duration of diarrhoea and diarrhoea lasting ≥ 4 days, as these are directly relevant to the development of persistent diarrhoea, and stool frequency on day 2 after intervention as a marker of diarrhoea severity.

This review is a substantial update of the original version, first published in 2003 (Allen 2003).

Objectives

To assess the effects of probiotics in proven or presumed acute infectious diarrhoea.

Methods

Criteria for considering studies for this review

Types of studies

Randomized and quasi‐randomized controlled trials reporting the effect of probiotic(s) on acute infectious diarrhoea. Studies of probiotics in acute diarrhoea that reported other outcomes (eg their effect on rotavirus shedding in stools) but no diarrhoea outcomes were not included.

Types of participants

Adults and children with acute diarrhoea (duration < 14 days) that was proven or presumed to be caused by an infectious agent.

Excluded: studies of diarrhoea known or thought to have other causes (eg antibiotic‐associated diarrhoea and studies of persistent diarrhoea).

Types of interventions

Intervention

Specific, identified probiotic.

Excluded: yogurt or other fermented foods in which specific probiotic organisms were not identified.

Control

Placebo or no probiotic.

Intervention and control arm to be otherwise treated identically in relation to other treatments and drugs.

Types of outcome measures

Primary

Duration of diarrhoea  Diarrhoea lasting ≥ 4 days  Stool frequency on day 2 after intervention

Secondary

Diarrhoea lasting ≥ 3 days

Stool frequency on day 3 after intervention

Search methods for identification of studies

We have attempted to identify all relevant studies regardless of language or publication status (published, unpublished, in press, and in progress). Searches of all databases was done on 1 July 2010.

We searched the Cochrane Infectious Diseases Group's trials register using the search terms: diarrhea/; diarr$(tw); diarhea(tw); probiotic(tw); Lactobacill$(tw); Lactococc$(tw); Bifidobacter$(tw); Enterococc$(tw); Streptococc$(tw); Saccharomyces(tw). Full details of the Cochrane Infectious Diseases Group's methods and the journals handsearched are published in The Cochrane Library in the section on 'Collaborative Review Groups'.

We searched the Cochrane Controlled Trials Register published on The Cochrane Library (Issue 2, 2010) using the search terms: diarrhea/; diarr$(tw); diarhea(tw); probiotic(tw); Lactobacill$(tw); Lactococc$(tw); Bifidobacter$(tw); Enterococc$(tw); Streptococc$(tw); Saccharomyces(tw).

We searched MEDLINE (1966 to 2010) and EMBASE (1988 to 2010 using the search strategy defined by The Cochrane Collaboration (Clarke 2003) and following search terms: diarrhea/; diarr$(tw); diarhea(tw); probiotic(tw); Lactobacill$(tw); Lactococc$(tw); Bifidobacter$(tw); Enterococc$(tw); Streptococc$(tw); Saccharomyces(tw).

The detailed search strategy is shown in Appendix 1.

In preparation for the original review (Allen 2003), we contacted organizations and individuals working in the field, and the following pharmaceutical companies that manufacture probiotic agents to help identify additional published trials and unpublished data: Biogaia Biologicals, Lund, Sweden; Nestle Foundation, Lausanne, Switzerland; Probiotics International Ltd, Somerset, UK; Ross Products Division of Abbott Laboratories, Ohio, USA, and Yakult, London, UK. We have not re‐contacted individuals or companies for this update.

We also drew on existing reviews of this topic and checked the citations of all trials identified by the above methods.

Data collection and analysis

Study selection

SA and LD independently reviewed the titles of articles and, where available, abstracts generated by the search to identify potentially relevant studies. All articles that could meet the inclusion criteria as identified by either of the reviewers were selected and the full article reviewed. Eligibility was assessed independently by SA and LD using a form based on the information presented in the article. We planned to contact trial authors if eligibility was unclear. Discrepancies among reviewers' eligibility assessments were resolved by discussion. Trial reports were scrutinized to ensure that multiple publications from the same trial were included only once. Excluded studies and the reasons for their exclusion were listed.

Assessment of methodological quality

Two reviewers (EM, GG), blinded to the origin of the articles, independently assessed the methodological quality of identified studies using generation of allocation sequence, allocation concealment, blinding, and loss to follow up, and we recorded this information on a standard form.

We considered the generation of allocation sequence to be adequate if the study authors stated that they used a method resulting in unpredictable sequences (such as a random number table or list or computer‐generated random numbers), unclear if a trial was stated to be randomized but no further information was provided and inadequate where allocation could be related to prognosis and therefore introduced selection bias (for example, the date of birth or date of admission to hospital).

We considered allocation concealment to be adequate if the assignment to arms of the study could not be predicted by the investigators or participants (for example, central randomization or numbered, identical drug containers), unclear if the method used to achieve concealment was not described or inadequate if they used a method such as alternation where the allocation of participants could be predicted.

We considered blinding to be adequate when studies were double blind (when an identical placebo was used and recruitment to intervention or control arms was not known by either the investigator or the participants), unclear if methods of blinding were not described adequately, and inadequate when blinding was not used or where the authors stated that unblinding had occurred.

We considered loss to follow up to be adequate when study endpoints were presented for 90% or more of the participants enrolled at the beginning, inadequate when follow up was less than this and unclear when either or both the number of participants recruited at the beginning of the study and the number of participants who completed the study were not clear.

LD resolved disagreements regarding the assessment of methodological quality.

Data extraction

SA, BO, SP, and SA independently extracted data using standard forms. Key data items were the aetiology and duration of diarrhoea, details of probiotic organism, participants' characteristics (nutritional and human immunodeficiency virus (HIV) status), location (countries classified according to mortality stratum; WHO 2001), and the outcome measures listed above. The number of participants recruited and the number for whom outcome data was reported were extracted and included in the Characteristics of included studies table.

For dichotomous outcomes, the number of participants experiencing the event, and the total number of participants in each intervention group was extracted. For continuous outcomes, arithmetic means, standard deviations (SD), and the numbers of participants in each intervention group was extracted. SDs were calculated from 95% CI and standard errors, where these were reported. The findings of trials that presented data that could not be included in pooled analyses (eg median and inter‐quartile range (IQR)), or reported outcomes other than the primary and secondary outcomes employed in this review were reported in the text.

Data analysis

We pooled data from studies that used comparable outcome measures. For the duration of diarrhoea and number of stools per day of intervention, we achieved a pooled estimate of treatment effect by calculating the weighted mean difference. For the number of participants with diarrhoea lasting 3 days or more, or 4 days or more after starting the intervention, we calculated a pooled estimate of the relative risk (RR) among probiotic and non‐probiotic groups.

We reported the proportion of participants for whom outcome data were available in a 'Risk of bias' table for each study. We performed analyses according to the intention‐to‐treat principle using an available case analysis approach.

Where there was significant heterogeneity (P < 0.1) in outcomes across studies assessed by the Chi² test a random‐effects model was used; otherwise a fixed‐effect approach was taken.

We inspected the forest plots to detect non‐overlapping CIs, applied the Chi² test and also implemented the I² statistic (with a value of ≥ 50%) to assess heterogeneity in findings. Where there was significant statistical heterogeneity in primary outcomes for the probiotic versus no probiotic group comparisons, we conducted sensitivity analyses according to each of the four parameters of trial methodological quality (Characteristics of included studies).

We proceeded to pool data for meta‐analysis to provide a qualitative assessment of probiotic effect as a guide to clinical practice.

We expected that heterogeneity in results among studies would result from clinical diversity, including differences in probiotic(s) used, dose of organisms, types of participants, causes and severity of diarrhoea and the socioeconomic status of countries where the studies were undertaken (Wolvers 2010). Therefore, where there were results for a diarrhoea outcome available from three or more studies we conducted subgroup analyses according to the:

probiotic strain; single probiotic organisms versus combinations of two or more organisms, dose of live organisms (high dose [> 10¹⁰ CFU/day] versus lower dose [≤10¹⁰ CFU/day]); killed organisms;
age of participants;
identified diarrhoeal pathogens (rotavirus, bacterial diarrhoea);
severity of diarrhoea according to whether the participants were likely to have had mild diarrhoea and were, therefore, managed as outpatients;
mortality stratum for children and adults in the country or countries where the trial was undertaken (WHO 2001) to account for regional differences in major diarrhoeal pathogens and diarrhoea severity related to the availability of clean water and level of sanitation. To facilitate meta‐analysis, countries were divided into two groups according to whether either child or adult mortality, or both, was classified as high.

Finally, we inspected funnel plots for the primary outcomes to assess publication bias.

Results

Description of studies

Our search identified 120 potentially relevant studies. Of these, 63 met the inclusion criteria. Overall, 57 studies were excluded, including five that were preliminary or duplicate reports of other included studies (Characteristics of excluded studies). Eligibility regarding inclusion in this review was clear for all studies and clarification from trial authors was not required. We have not been able to locate the reports of two studies (Contreras 1983; Salgado) and one study is ongoing (Freedman 2010). None of the 56 included trials were cluster randomized.

Publication status

Of the 63 included studies, 23 were published in the 1980s‐1990s, 37 between 2000‐2009 and two in 2010; one study was unpublished.

Study location

According to country mortality strata for children/adults (WHO 2001), 41 trials were undertaken in countries where both child and adult mortality was classified as low or very low and 19 where either child or adult mortality was high. Two international studies recruited participants from countries crossing the mortality strata (Guandalini 2000; Jasinski 2002). Finally, the study by Ritchie 2010 was undertaken in Australia (very low child and low adult mortality) but recruited Aboriginal children who commonly had co‐morbidities such as pneumonia and malnutrition related to poverty and social disadvantage in the top end of the Northern Territory. Therefore, data from this study were not included in analysis according to country mortality strata.

A total of 47 studies were conducted in a single centre; 15 recruited participants from two to 150 centres. The number of recruitment centres was unclear in one study (D'Apuzzo 1982).

Participants

The 63 selected studies recruited a total of 8014 participants. There were 6489 infants and children (age < 18 years) and 352 adults. In three studies (1173 participants) the exact ages of participants was not clear: Bruno 1983 studied participants aged 14 years and above, participants in Wunderlich 1989 had a mean age of 33 years (age range not stated) and the age of the participants in Frigerio 1986 was not stated.

Forty‐four studies recruited inpatients, seven recruited outpatients and seven recruited both inpatients and outpatients. It was unclear in five studies whether the participants were inpatients or outpatients.

Although all studies recruited participants with acute diarrhoea, the criteria for acute diarrhoea varied considerably among studies (see Characteristics of included studies). Descriptions of stool consistency included watery, loose or liquid stools, or both, semi‐liquid, increased fluidity, pasty, mucousy or non‐formed in 46 studies but no description was stated in 17 studies. The minimum number of stools/day was specified in 36 studies; this ranged from ≥one to ≥ five stools with the most commonly used criteria being ≥ three (16 studies) and ≥four stools in 24 hours (13 studies). One study specified stool frequency as at least twice normal frequency, one as increased frequency and in one study stool consistency was taken into account. The minimum number of stools was not specified in 24 studies. The maximum duration of diarrhoea at recruitment was specified in 40 studies and varied between one and 14 days. The maximum diarrhoea duration was not specified in 23 studies.

Similarly, criteria used for the end of the diarrhoeal episode varied markedly among studies. The last liquid or watery stool (nine studies) and first normal stool (seven studies) were the most common. Twenty‐one studies used a variety of criteria based on stool frequency and consistency in a specified period (eg first formed stool if followed by two consecutive non‐watery stools or 12 hours without evacuation; Mao 2008). Four studies also included the resolution of associated symptoms (eg < two stools/day, formed, yellow/brown stools without mucus and no abdominal pains, vomiting, or fever for the whole day; D'Apuzzo 1982). Criteria were not stated in 17 studies.

Eighteen studies were either restricted to children with rotavirus diarrhoea or reported outcomes for a subgroup of children with rotavirus diarrhoea. Children with rotavirus diarrhoea were excluded in one study (Lievin Le‐Maol 2007). Ten studies stated that participants with bloody diarrhoea were included whereas these were excluded in 32 studies. It was unclear whether participants with bloody diarrhoea were included in 21 studies. No study specifically recruited or excluded travellers, and none identified any of the participants as suffering from travellers' diarrhoea.

No study specifically recruited participants known to have HIV infection and no study stated HIV positivity as an exclusion criterion, but many excluded participants with chronic illness or immunosuppression, or both.

Nutritional status was reported in 35 studies, all undertaken in children. Ten studies either recruited malnourished children only or included malnourished children; 20 studies excluded severe malnutrition; five studies recruited well‐nourished children only or excluded those with a chronic illness.

Twenty‐six studies excluded participants who had received antibiotic treatment before recruitment, eight included participants who had received antibiotic treatment before recruitment and this information was unclear in 29 studies.

The hydration status of the participants was reported in 35 studies; 22 studies included participants with severe dehydration whereas 10 studies recruited only children with mild or moderate dehydration.

Interventions

Many different probiotics were tested. Most studies tested live preparations of lactic acid bacteria and bifidobacteria. Several studies identified the probiotic organisms only by the species name without specific identification details such as a culture collection number. Few studies undertook analyses to confirm the identity or viability of the organism(s).

Forty‐six studies tested a single organism and 17 tested combinations of between two to eight organisms. The most common organisms evaluated were L. casei strain GG (13 studies), S. boulardii (10 studies) and Enterococcus lactic acid bacteria (LAB) SF68 (five studies). All other organisms and all combinations were tested in three or fewer studies. Canani 2007 allocated children to one of five different probiotic regimens and compared outcomes with a single control group. For the purposes of this review, we selected the L. casei GG group for inclusion because several other studies tested this probiotic and we wanted to maximize the data available for meta‐analysis. Grandi 2009 allocated children either to a single organism or a four‐organism group and compared outcomes with a single control group. No data extractable for meta‐analysis were reported in this study.

Forty‐seven studies tested live organisms, five studies tested a killed probiotic preparation (Billoo 2006; Boulloche 1994; Lievin Le‐Maol 2007; Simakachorn 2000; Khanna 2005), and one a pasteurized yogurt (Pashapour 2006). The viability of the organisms was unclear in 10 studies.

Three studies compared different dosages (number of organisms) of the same probiotic (Basu 2009, Mao 2008, Shornikova 1997b) with a single control group. We selected the higher probiotic dose group for inclusion in the review but have included results from the lower dose group in the text. Overall, 15 studies used a high dose of organisms (> 10¹⁰ CFU/day), 26 used a low dose (≤ 10¹⁰ CFU/day) and the dose was unclear in 22 studies.

As well as differences in dose or organisms, there was a wide variation in the treatment regimens according to timing of intervention, means of administration and duration of treatment. Probiotics were administered directly to the participants or mixed with a variety of fluids and foods. Although expressed breast milk was used to administer probiotics in some studies, some studies excluded exclusively breast‐fed infants to minimize the interruption of normal feeding.

Forty‐three studies used a placebo in the no probiotic control group; the remaining studies managed participants according to usual clinical practice.

Risk of bias in included studies

Methodological quality varied considerably (see Characteristics of included studies). Twenty‐three studies were considered adequate for generation of the allocation sequence, 15 for concealment of allocation, 35 for blinding and 45 for loss to follow up. Ten studies were adequate for all of the four methodological quality assessment parameters and five studies were inadequate for all four parameters.

Effects of interventions

Primary outcomes

The forest plots demonstrate that probiotics reduce the duration of diarrhoea. Values for duration of diarrhoea in the control arm varied widely, from 39.1 to 173.5 hours, and the difference between the intervention groups ranged from ‐79.2 to 7.0 hours (Analysis 1.1). Similar variability was evident in the other outcomes. Despite the high level of quantitative heterogeneity, the pattern was striking, and meta‐analysis shows an important effect which is statistically significant. Using a random effects approach, probiotics reduced the mean duration of diarrhoea (mean difference 24.76 hours; 95% confidence interval 15.9 to 33.6 hours; n=4555, trials=35; Analysis 1.1), diarrhoea lasting ≥4 days (risk ratio 0.41; 0.32 to 0.53; n=2853, trials=29; Analysis 1.2) and stool frequency on day 2 (mean difference 0.80; 0.45 to 1.14; n=2751, trials=20; Analysis 1.3). The differences in these analyses are an average across all studies with quantitative heterogeneity, demonstrating that probiotics have a substantive and significant effect, rather than being a precise estimate of the size of the effect.

1.1 — Comparison 1 Primary diarrhoea outcomes, Outcome 1 Mean duration of diarrhoea.

1.2 — Comparison 1 Primary diarrhoea outcomes, Outcome 2 Diarrhoea lasting ≥4 days.

1.3 — Comparison 1 Primary diarrhoea outcomes, Outcome 3 Mean stool frequency on day 2.

The funnel plots for the primary outcomes (Figure 1, Figure 2, Figure 3) did not indicate publication bias as the largest intervention effects were observed in studies with a large number of participants as well as smaller studies.

Funnel plot of comparison: 1 Primary diarrhoea outcomes, outcome: 1.1 Mean duration of diarrhoea.

Funnel plot of comparison: 1 Primary diarrhoea outcomes, outcome: 1.2 Diarrhoea lasting ≥ 4 days.

Funnel plot of comparison: 1 Primary diarrhoea outcomes, outcome: 1.3 Mean stool frequency on day 2.

Secondary outcomes

The findings for diarrhoea lasting ≥ 3days (Analysis 2.1) and stool frequency on day 3 after intervention (Analysis 2.2) were broadly similar to the primary outcomes and there was also marked statistical heterogeneity among studies.

2.1 — Comparison 2 Secondary diarrhoea outcomes, Outcome 1 Diarrhoea lasting ≥3 days.

2.2 — Comparison 2 Secondary diarrhoea outcomes, Outcome 2 Mean stool frequency on day 3.

Seven studies reported diarrhoea outcomes data that could not be included in analyses. Billoo 2006 evaluated S. boulardii in infants and children admitted with acute watery diarrhoea of mild to moderate severity in Pakistan. The mean duration of diarrhoea was reduced in the probiotic compared with the control group (n = 50, 86.4 hours versus n = 50, 115.2 hours, respectively; P = 0.001). Stool frequency on days 3 (P = 0.01) and 6 (P = 0.001) was also reduced in the probiotic group. Czerwionka 2009 evaluated Lactobacillus rhamnosus in children with acute diarrhoea in Poland. The total number of stools per child was statistically significantly lower in the probiotic group than the controls. Misra 2009 evaluated L. rhamnosus GG in children in India. The mean duration of diarrhoea was 70.6 hours in the probiotic and 78.0 hours in the control group (P = 0.20).

Grandi 2009 allocated young children admitted with acute rotavirus diarrhoea to receive either oral rehydration fluid (ORF) + S. boulardii, ORF + Lactobacillus acidophilus, L. rhamnosus, Bifidobacterium longum andS. boulardii, or ORF alone (control group). The median duration of diarrhoea was shorter in both of the probiotic groups compared with the controls but this was statistically significant only for S. boulardii (58 hours versus 84.5 hours, respectively; P = 0.04).

In a short abstract, Frigerio 1986 reported that the duration of diarrhoea was significantly reduced (P < 0.01) among 540 patients with an acute diarrhoeal disorder attending hospitals in Italy who received Enterococcus LAB SF 68 compared with 534 who received a placebo.

In a further study, Sepp 1995 evaluated adding L. casei GG to trimethoprim‐sulfamethoxazole, compared to trimethoprim‐sulfamethoxazole alone, in children with acute diarrhoea caused by shigellosis in Estonia. The duration of diarrhoea was similar in the probiotic (median 0.5 days) and the control group (1 day; not statistically significant). Also, the proportion of children with ongoing diarrhoea on day 5 was similar in the probiotic and control groups (6/13 (46.3%) versus 9/12 (75.0%); not statistically significant). However, a greater proportion was cured in the probiotic than the control group on day 10 (P < 0.05). Finally, in an open study, Táborská 1997 evaluated live L. acidophilus ND in infants and children admitted with acute gastroenteritis in the Czech Republic. The resolution of enteric symptoms during days 1 to 5 of the intervention was similar in the two groups.

Exploration of heterogeneity

Sensitivity analysis for primary outcomes

When analysis was restricted to trials assessed to be adequate for the four criteria of study quality (Characteristics of included studies), highly statistically significant between‐study heterogeneity persisted (forest plots not shown (Table 10). This suggests that differences in outcomes between studies were caused by factors other than differences in methodological quality.

1. Heterogeneity in sensitivity analysis of primary outcomes¹.

Sensitivity analysis	Outcome	Studies (no.)	χ²	P value	I^{2 (%)}
Generation of allocation sequence	Mean duration diarrhoea Diarrhoea ≥4 days Stool frequency day 2	16 13 9	1077.2 46.2 26.9	< 0.00001 < 0.00001 0.0007	99 74 70
Concealment of allocation sequence	Mean duration diarrhoea Diarrhoea ≥4 days Stool frequency day 2	14 8 8	438.3 34.2 42.4	< 0.00001 < 0.0001 < 0.00001	97 8% 83
Blinding	Mean duration diarrhoea Diarrhoea ≥4 days Stool frequency day 2	26 16 14	1070.9 64.8 48.8	< 0.00001 < 0.00001 < 0.00001	98 77 73
Follow‐up	Mean duration diarrhoea Diarrhoea ≥4 days Stool frequency day 2	25 19 15	672.3 52.3 54.5	< 0.00001 < 0.0001 < 0.00001	96 66 74

Date	Event	Description
11 August 2010	New citation required but conclusions have not changed	Title changed ("acute" added) to emphasise that persistent diarrhoea is not considered. The authorship of the update has changed due to the untimely death of Dr Okoko.
11 August 2010	New search has been performed	The table showing clinical variability among studies has been removed and this information added to the Characteristics of included studies table. A table has been added to show the marked statistical heterogeneity in primary outcomes and subgroup analyses (Table 10). The following secondary outcomes have been removed as they were either uncommon or not reported: need for unscheduled intravenous (IV) rehydration after randomization; deaths; adverse events, such as vomiting; withdrawal from study. Details regarding adverse events and reasons for withdrawal are included in the "details of included studies" table.
22 July 2008	Amended	Converted to new review format.
8 December 2007	New citation required and conclusions have changed	Substantive amendment

Search set	CIDG SR^a	CENTRAL	MEDLINE^b	EMBASE^b	LILACS^b
1	Diarrhea*	DIARRHEA	DIARRHEA	INFECTIOUS DIARRHEA	Diarrhea$
2	Diarrhoea*	Diarrhoea*	Diarrhoea*	Diarrhoea*	Diarrhoea$
3	1 or 2	1 or 2	1 or 2	1 or 2	1 or 2
4	Probiotic*	Probiotic*	PROBIOTICS	PROBIOTIC AGENT	Probiotic$
5	Lactobacill*	Lactobacill*	Lactobacill*	Lactobacill$	Lactobacill$
6	Lactococc*	Lactococc*	Lactococc*	Lactococc$	Lactococc$
7	Bifidobacter*	Bifidobacter*	Bifidobacter*	Bifidobacter$	Bifidobacter$
8	Enterococc*	Enterococc*	Enterococc*	Enterococc$	Enterococc$
9	Streptococc*	Streptococc*	Streptococc*	Streptococc$	Streptococc$
10	saccharomyces	saccharomyces	saccharomyces	saccharomyces	saccharomyces
11	4 or 5 or 6 or 7 or 8 or 9 or 10	4 or 5 or 6 or 7 or 8 or 9 or 10	4 or 5 or 6 or 7 or 8 or 9 or 10	4 or 5 or 6 or 7 or 8 or 9 or 10	4 or 5 or 6 or 7 or 8 or 9 or 10
12	3 and 11	3 and 11	3 and 11	3 and 11	3 and 11
13			Limit 12 to Humans	Limit 12 to Human

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mean duration of diarrhoea	35	4555	Mean Difference (IV, Random, 95% CI)	‐24.76 [‐33.61, ‐15.91]
2 Diarrhoea lasting ≥4 days	29	2853	Risk Ratio (M‐H, Random, 95% CI)	0.41 [0.32, 0.53]
3 Mean stool frequency on day 2	20	2751	Mean Difference (IV, Random, 95% CI)	‐0.80 [‐1.14, ‐0.45]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Diarrhoea lasting ≥3 days	30	3022	Risk Ratio (M‐H, Random, 95% CI)	0.62 [0.56, 0.70]
2 Mean stool frequency on day 3	14	2367	Mean Difference (IV, Random, 95% CI)	‐0.63 [‐1.18, ‐0.07]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mean duration of diarrhoea	11		Mean Difference (IV, Random, 95% CI)	Subtotals only
1.1 Live Lactobacillus casei strain GG	11	2072	Mean Difference (IV, Random, 95% CI)	‐26.69 [‐40.50, ‐12.88]
2 Diarrhoea lasting ≥4 days	14		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
2.1 Live Lactobacillus casei strain GG	4	572	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.40, 0.87]
2.2 LIve Enterococcus LAB SF68	4	333	Risk Ratio (M‐H, Random, 95% CI)	0.21 [0.08, 0.52]
2.3 Saccharomyces boulardii	6	606	Risk Ratio (M‐H, Random, 95% CI)	0.37 [0.21, 0.65]
3 Mean stool frequency on day 2	6		Mean Difference (IV, Random, 95% CI)	Subtotals only
3.1 Live Lactobacillus casei strain GG	6	1335	Mean Difference (IV, Random, 95% CI)	‐0.76 [‐1.32, ‐0.20]

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mean duration of diarrhoea	12	701	Mean Difference (IV, Random, 95% CI)	‐29.14 [‐42.07, ‐16.20]
2 Mean stool frequency on day 2	3	164	Mean Difference (IV, Random, 95% CI)	‐1.25 [‐2.09, ‐0.41]

Methods	Randomized controlled trial; 1 centre Duration: 1 year (January ‐December 2003)
Participants	Inclusion criteria: inpatients; infants and children with ≥ 3 watery stools/day without visible blood or mucus (duration not stated); < 10 white blood cells/high power field and no red cells, mucus flakes and bacteria on stool microscopy; negative hanging drop preparation; negative bacterial stool culture. Exclusion criteria: systemic illness other than diarrhoea on admission; systemic complication of diarrhoea during hospital stay; failure to give informed consent. Number completing study: 323/330 (97.9%) in the probiotic group (3 participants had electrolyte imbalance, 2 had septicaemia, 2 withdrew consent); 323/332 (97.3%) in control group (3 participants had electrolyte imbalance, 2 had septicaemia, 2 withdrew consent, 1 was discharged, 1 died).
Interventions	Live L. rhamnosus GG (120 x 10⁶ CFU/day for 7 days) ORF Dehydration was corrected using oral rehydration fluid (ORF) following WHO guidelines
Outcomes	Frequency of diarrhoea Duration of diarrhoea (time to 2 consecutive soft or formed stools or no stool for 12 consecutive hours) Duration of vomiting Length of hospital stay No adverse events attributed to probiotic.
Notes	Study location: India (high child and adult mortality) Cause of diarrhoea: bacterial diarrhoea excluded. Rotavirus identified in 241 (74.6%) probiotic and 249 (77.1%) control group. Nutritional status: most participants malnourished: probiotic group; 198/323 moderately malnourished, 31/323 severely malnourished; control group; 185/323 moderately malnourished, 33/323 severely malnourished. Hydration status: all participants dehydrated: probiotic group: 48 mild, 173 moderate, 102 severe dehydration; control group: 51 mild, 168 moderate, 104 severe dehydration. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	computer randomization
Allocation concealment?	Low risk	concealed in envelopes
Blinding?   All outcomes	Low risk	double blind
Incomplete outcome data addressed?   All outcomes	Low risk	Follow‐up ≥90% in both groups

Methods	Randomized controlled trial; 2 centres. Duration: 16 months
Participants	Inclusion criteria: inpatients; malnourished boys (weight for height < 80% NCHS median) with diarrhoea (≥ 5 liquid stools in preceding 24 hours) for ≤ 96 hours. Nearly all children were dehydrated (48/49 milk group and 43/47 yogurt group). Exclusion criteria: females; severe non‐gastrointestinal illness; gross blood in the stools; exclusive breast‐feeding. Number completing study: 47/49 (95.9%) in probiotic group (2 withdrawn because cholera in stool cultures); 49/53 (92.5%) in control group (2 withdrawn because cholera in stool cultures and 2 left against medical advice).
Interventions	Yogurt formula (Lactogen‐2, Nestle India Ltd; after fermentation with 90 g S. thermophilus and Lactobacillus bulgaricus standard starter (International Yoghurt Manufacturers Club, Paris) 120 mL/kg/day for at least 72 hours) added to milk formula Non‐fermented Lactogen‐2 Given after 8 hours initial observation. All participants received rehydration fluids (IV if stool > 4 g/kg/hour), IV cephalosporin and gentamicin, and fed with rice lentil oil gruel.
Outcomes	Proportion recovered at 48 hours and 72 hours (defined as 2 consecutive formed stools, ≤3 stools in 24 hours of which at least 2 were formed, or no stool for 12 hours) Median duration of diarrhoea Treatment failures (episode of diarrhoea after 72 hours or stool weight > 150 g/kg on any day) No comment regarding adverse events.
Notes	Study location: India (high child and adult mortality). Cause of diarrhoea: excluded if gross bloody stools. Nutritional status: all malnourished boys (weight for height < 80% NCHS median); mean weight for length and length for age (% NHCS median) similar in both groups. Hydration status: Nearly all children were dehydrated: 43/47 (91.5%) probiotic and 48/49 (98.0%) control group. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	randomisation list
Allocation concealment?	Unclear risk	not stated
Blinding?   All outcomes	Unclear risk	probably open study
Incomplete outcome data addressed?   All outcomes	Low risk	Follow‐up ≥ 90% in both groups

Methods	Randomized trial; probably open study; 1 centre Duration: not stated
Participants	Inclusion criteria: inpatients; infants and children with acute watery diarrhoea of mild to moderate severity Exclusion criteria: Severe intercurrent illness; severe diarrhoea and dehydration requiring admission and IV rehydration; temperature > 38.5°C; anti‐diarrhoeals or antibiotics in last 24 hours; severe malnutrition Number completing study: 50/50 (100%) in probiotic group; 50/50 (100%) in control group.
Interventions	S. boulardii (500mg/day for 5 days) ORF and nutritional support only Timing of interventions not stated.
Outcomes	Stoppage of diarrhoea (not defined) Weight gain Daily stool frequency and consistency Tolerance and acceptability of intervention No adverse events attributed to probiotic.
Notes	Study location: Pakistan (high child and adult mortality) Cause of diarrhoea: Rotavirus identified in 8 (16.0%) probiotic and 10 (20.0%) control group. Bacterial diarrhoea identified in 13 (26.0%) probiotic and 6 (12.0%) control group. Nutritional status: severe malnutrition excluded; no further data presented Hydration status: severe dehydration excluded; no further data presented Source of funding: supported by Laboratoires Biocedex (France); Hilton Pharma (Pvt.) Ltd. Pakistan
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Randomized controlled trial but methods not described
Allocation concealment?	Unclear risk	Methods not described
Blinding?   All outcomes	High risk	No placebo; probably open study
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥90% in both groups

Methods	Randomized controlled trial; 1 centre. Duration: 3 years
Participants	Inclusion criteria: inpatients; young children with acute diarrhoea (definition not stated; 3/4 had diarrhoea < 3 days); weight loss of at least 5%. Exclusion criteria: any treatment that could have affected diarrhoea during hospitalization. Number completing study: 38/38 (100%) in probiotic group and 33/33 (100%) in control group.
Interventions	Killed L. acidophilus (LB strain, Lacteol Forte, France; 1 sachet thrice daily for first 24 hours, then 1 sachet daily for next 3 days) Placebo (no details provided; same regimen) Loperamide Timing of start of administration not stated. All young infants were given Pregestimil, and older children were given an anti‐diarrhoeal diet.
Outcomes	Time to first normal stool Failure defined as no improvement by the end of day 2 (clinical criteria) No adverse events attributed to probiotic.
Notes	Study location: France (very low child and adult mortality). Cause of diarrhoea: 18% all participants had positive stool cultures and 49% positive virology tests (no further details given). Nutritional status: no data presented. Hydration status: all dehydrated with weight loss of at least 5%. Results presented for oral rehydration group only and all children. Resolution of diarrhoea in killed L. acidophilus group similar for rotavirus positive and negative participants. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Random number table stratified in groups of 18
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Unclear risk	Not described
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 6 centres Duration: 12 months, October 1999 to September 2000
Participants	Inclusion criteria: outpatients; infants and children aged 3 to 36 months with >2 loose or liquid stools/day for <48 hours. Exclusion criteria; malnutrition, severe dehydration; coexisting acute systemic illness (meningitis, sepsis, pneumonia), immunodeficiency; underlying severe chronic disease; cystic fibrosis; food allergy or other chronic GI diseases; use of probiotics in the previous 3 weeks; antibiotics or any other antidiarrhoeal medication in the previous 3 weeks; poor compliance (< 4 doses of the study medication administered). Number completing study: 95/100 in the probiotic group (2 did not receive the allocated intervention, 1 faster remission, 1 worsening symptoms, 1 poor compliance); 88/92 in the control group (1 did not receive the allocated intervention, 1 worsening symptoms, 1 contracted pneumonia, 1 had coeliac disease).
Interventions	Live Lactoacillus casei rhamnosus GG (Dicoflor 60; 12 x 10⁹ CFU/day for 5 days) Placebo, no details given but same appearance as active intervention. Intervention started within 48 hours of admission. ORF given for 3‐6 hours after admission, lactose‐containing formula milk or cow's milk according to age.
Outcomes	Diarrhoea duration (time of the last loose or liquid stool preceding a normal stool) Number and consistency (scoring system) of stools/day recorded by parents Vomiting Fever (> 37.5°C) Number of hospital admissions 1 patient with poor compliance in the probiotic group; 31 and 34 participants had vomiting in the probiotic and placebo groups, respectively. No adverse events attributed to probiotic.
Notes	Study location: Italy (very low child and adult mortality). Cause of diarrhoea: stool culture in only few participants; no data presented. Nutritional status: malnutrition excluded Hydration status: severe dehydration excluded; no other data presented. Source of funding: none Single blind trial. Parents instructed to buy probiotic preparation. This study also allocated children to 4 other probiotic groups: 1) S. boulardii It 5 × 10⁹ live organisms daily (Codex) for 5 days; 2) Bacillus clausii O/C84, N/R84, T84, SIN84 (Enterogermina) 10⁹ CFU bd for 5 days; 3) a combination of L. delbrueckii var bulgaricus LMG‐P17550 10⁹ CFU daily, L. acidophilus LMG‐P 17549 109 CFU daily, S. thermophilus LMG‐P 17503 10⁹ CFU daily, B. bifidum LMG‐P 17500 5 × 10⁸ CFU daily (Lactogermina) for 5 d; 4) Enterococcus faecium SF 68 (Bioflorin) 7.5×10⁷ CFU daily for 5 days and compared each of the probiotic groups with the single control group. Mean duration of diarrhoea and mean stool frequency on day 2 and 3 were significantly shorter than in the control group for intervention groups 1 and 3. These outcomes were similar to the control group for the other probiotic groups. To avoid a unit‐of‐analysis error as a result of the multiple comparisons between the intervention groups and the single control group, we elected to include data for the L. GG group only in this review. We selected L. GG because this was the probiotic most frequently evaluated in acute infectious diarrhoea and we wished to maximize the body of evidence. We rejected the alternative approach of pooling the data from all of the different probiotic intervention groups into a single group because this would not be helpful in selecting a specific probiotic intervention for use in clinical practice.
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Computer‐generated randomization list allocation in blocks of 6
Allocation concealment?	Low risk	Concealed until treatment assigned
Blinding?   All outcomes	Low risk	Blinded third‐party blind assessor
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Intervention study; 1 centre Duration: not stated
Participants	Inclusion criteria: inpatients; infants and children with sudden, recent onset of watery diarrhoea (not defined) of variable importance with or without fever and vomiting. Exclusion criteria: dehydration >10% needing IV rehydration; bloody or purulent stools; fever >39°C; associated pathology. Number completing study: 19/19 (100%) probiotic group and 19/19 (100%) control group.
Interventions	Live S. boulardii (500 mg/day for 5 days) ORF When the probiotic was administered was not stated.
Outcomes	Mean number of stools, mean stool weight and carmine red transit time on days 1 and 4. Stool consistency on day 4. Stool frequency on day 4 was lower in the probiotic than the control group (n = 19; mean 2.1 [SD 0.9] versus n = 19; 3.4 [1.9] respectively). The reduction in stool frequency from baseline was statistically significantly greater in the probiotic than control group (P < 0.01). No adverse events attributed to probiotic.
Notes	Location: France (very low child and adult mortality) Cause of diarrhoea: bloody or purulent stools excluded; pathogenic bacteria isolated from 9 children in the probiotic and 6 in the control group. Nutritional status: no data presented. Hydration status: dehydration > 10% needing IV rehydration excluded; Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Infants allocated alternately to the two groups as enrolled in trial
Allocation concealment?	High risk	Alternate allocation
Blinding?   All outcomes	High risk	No placebo; open study
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; unclear whether single or multi‐centre. Duration: not stated
Participants	Inclusion criteria: unclear whether inpatients or outpatients, or both; children with acute enteritis (duration and definition not given). Exclusion criteria: none stated. Number completing study: 21/21 (100%) in the probiotic group and 18/18 (100%) in the control group.
Interventions	Live Streptococcus faecium (S. faecium 68; 75 x10⁶ bacteria thrice daily for 7 days) Placebo (details not given). When interventions started not stated.
Outcomes	Number of participants with < 2 stools/day. Formed, yellow/brown stools without mucus. No abdominal pains vomiting or fever for the whole day. No adverse events attributed to probiotic.
Notes	Study location: Switzerland (very low child and adult mortality). Cause of diarrhoea: 7 participants in each group had positive stool cultures for bacteria. Nutritional status: no data presented Hydration status: no data presented S. faecium 68 also appeared to promote recovery from abdominal pains, fever, and vomiting. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Unclear risk	Unclear whether placebo identical to probiotic
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 150 hospitals Duration not stated
Participants	Inclusion criteria: acute diarrhoeal disorder; diarrhoea defined as ≥ 3 not formed stools/day; duration not stated Exclusion criteria: not stated Number participants recruited at baseline not reported. 534 patients in the placebo group and 540 in the probiotic group completed the study.
Interventions	Enterococcus SF 68 (Bioflorin; 3 caps/day for 7 days) Placebo (not details given) When interventions started not stated.
Outcomes	Duration of diarrhoea (only statistical analysis reported; no raw data) No adverse effects attributed to probiotic.
Notes	Study location: Italy (very low child and adult mortality) Cause of diarrhoea: no data presented Nutritional status: no data presented Hydration status: no data presented Source of funding: not stated Probiotic also evaluated in antibiotic‐associated diarrhoea
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Random allocation; no details reported
Allocation concealment?	Unclear risk	No details reported
Blinding?   All outcomes	Unclear risk	No details regarding placebo reported.
Incomplete outcome data addressed?   All outcomes	Unclear risk	Number participants recruited not reported

Methods	Randomized controlled trial; multi‐centre Duration: 1 year, 1996
Participants	Inclusion criteria: inpatients and outpatients; infants and children with > 4 liquid or semi‐liquid stools/day for 1 to 5 days. Exclusion criteria: previous probiotic usage; underlying chronic untreated small bowel disease; inflammatory bowel disease; any underlying chronic disease or immunosuppressive disease or treatment. Number completing study: 287 forms (269 participants) of total of 323 forms (88.9%) received at the coordinating centre were analysed (36 incomplete data or not compliant with protocol); unclear whether withdrawals occurred at participating centres.
Interventions	L. GG (ATC 53103, ≥10 x 10⁹ CFU/250 ml) with ORF ORF with placebo Interventions added to ORF and started at recruitment.
Outcomes	Number of treatment failures (need for IV fluids) Mean duration of diarrhoea (time to last recorded fluid stool) Weight gain Proportion of children with diarrhoea longer than 7 days Mean stool frequency by day of treatment (SDs not given) Mean hospital stay Some outcomes also reported for rotavirus, bacterial, and no organism‐isolated subgroups. No comment regarding adverse events.
Notes	Study locations: Poland (low child and adult mortality), Egypt (high child and high adult mortality), Croatia, Italy, Slovenia, The Netherlands, Greece, Israel, United Kingdom, Portugal (all very low child and very low adult mortality). Cause of diarrhoea: rotavirus (56 probiotic/45 placebo); bacteria (35/34); parasites (7/6); no pathogen (45/54). 10 (6.8) probiotic and 15 (10.7) control group had bloody diarrhoea. Nutritional status: no data presented. Hydration status: severe dehydration in 1 (0.7) probiotic and 1 (0.7) control group; mild/moderate dehydration in 107 (72.7%) probiotic and 96 (68.2%) control group. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Low risk	Code broken at end of study
Blinding?   All outcomes	Unclear risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	Unclear risk	Unclear whether withdrawals occurred at participating centres; also 36/323 (11.2%) participant data forms received at the co‐ordinating centre were not analysed as incomplete and/or not compliant with protocol.

Methods	Randomized controlled trial ‐ randomization according to odd and even participant numbers; three centres Duration: 2 months
Participants	Inclusion criteria: outpatients; children aged 6 months to 5 years with acute watery diarrhoea of mild or moderate severity (not defined), suitable for ambulatory treatment. Exclusion criteria: anti‐diarrhoeals or antibiotics before admission, grade III malnutrition, bloody diarrhoea, needed IV rehydration, diarrhoea for >14 days. Number completing study: 51/54 (94%) probiotic group and 50/54 (93%) control group.
Interventions	Lyophilized S. boulardii (500 mg/day for 6 days) standard treatment (oral rehydration and feeds) Unclear whether researchers and participants able to distinguish between interventions.
Outcomes	Frequency and consistency (loose vs. formed) of stools Duration of illness (definition of end of diarrhoea not stated). Tolerance of treatment No adverse events attributed to probiotic.
Notes	Study location: Pakistan (high child and adult mortality). Cause of diarrhoea: bloody diarrhoea excluded; stool analysis not done. Nutritional status: grade III malnutrition excluded Hydration status: participants who needed IV rehydration excluded.. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Alternate allocation
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Unclear risk	Probably open study; no placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 11 centres Duration: 3 months, February to April 2005
Participants	Inclusion criteria: outpatients; infants and toddlers < 4 years with > 3 watery or loose and non‐bloody stools /day for ≤ 3 days. Exclusion criteria: > 5% dehydration; intake of E. coli Nissle 1917 in last 3 months; intake of food supplements or drugs which contain living microorganisms or their metabolic products or components within 7 days prior to enrolment or during the trial; other antidiarrhoeal drugs; breast‐feeding, premature birth; severe or chronic disease of the bowel or severe concomitant diseases. Antibiotics stated as exclusion criteria but some children included. Number completing study: 54/55 (98.2%) probiotic group and 45/58 (93.8%) control group. Reason for withdrawals in both groups stated as intervention no longer suitable or required other treatment.
Interventions	Live E. coli strain Nissle 1917 (Mutaflor suspension; 100‐300 x10⁶ organisms/day according to age) Placebo
Outcomes	Number of stools, stool consistency, admixture of blood or mucus Frequency of vomiting, abdominal pain and cramps Fluid intake, concomitant medication and general state of health for up to 10 days Diarrhea resolution: reduction in stool frequency to < 3 watery or loose stools in 24 hours over a period of at least 2 consecutive days. Adverse effects: 1 had rhinitis and 1 had abdominal cramps in the probiotic group. 2 had acute otitis media in the placebo group. 1 participant with poor compliance in the placebo group. No adverse events attributed to probiotic.
Notes	Study location: Ukraine, Russia (low child, high adult mortality) Cause of diarrhoea: bloody diarrhoea excluded; 16/55 (29.1%) probiotic and 19/58 (32.8%) control group had viral diarrhoea. Bacterial pathogens isolated from 9/55 (16.4%) probiotic and 4/58 (6.8%) control group. Nutritional status: most children well nourished. Hydration status: > 5% dehydration excluded; 0/55 probiotic and 1/58 control children had mild dehydration. Better outcomes in probiotic than placebo for abdominal pain (28/30 vs. 24/33) and abdominal cramps (17/18 vs. 21/26).  Parents reported slightly better tolerance of probiotic than placebo, although investigators noted no difference. Authors supplied data regarding SDs for diarrhoea duration. Source of funding: ARDEYPHARM provided verum and placebo medications and reimbursed study‐related expenses
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Computer‐generated randomly permuted blocks of 4
Allocation concealment?	Low risk	Sequence concealed from parents and researchers
Blinding?   All outcomes	Low risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial ‐ participants alternately assigned to the probiotic or control group on hospital admission; 1 centre Duration: not stated
Participants	Inclusion criteria: inpatients; infants and children aged 3 months to 10 years; acute watery diarrhoea of duration < 7 days. Exclusion criteria: fever > 38°C; severely dehydrated; macroscopic blood in the stools; intake of antifungals; existing severe malnutrition. Number completing the study: 50 (100%) probiotic group, 50 (100%) control group.
Interventions	S. boulardii (500 mg/day for 5 days) ORF according to WHO protocol Interventions started on admission.
Outcomes	Mean duration of diarrhoea (diarrhoea resolution: <3 stools/day or solid stools only) Stool frequency Consistency of stools No adverse events attributed to probiotic.
Notes	Study location: Myanmar (high child and high adult mortality) Cause of diarrhoea: bloody diarrhoea excluded Nutritional status: severe malnutrition excluded, no other data presented Hydration status: severe dehydration excluded, no other data presented SDs for the duration of diarrhoea were not reported. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Alternate allocation
Allocation concealment?	High risk	Alternate allocation
Blinding?   All outcomes	High risk	Probably open study; no placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 12 centres Duration: not stated
Participants	Inclusion criteria: inpatients and outpatients; age 1month to 3 years; acute diarrhoea (3 or more liquid stools in 12 hours or single liquid or semi‐solid stool with mucus or blood, or both, for 5 days or less). Exclusion criteria: antibiotics or probiotics in last 5 days; chronic diseases of small or large intestine (eg coeliac, cow milk protein allergy, inflammatory bowel disease), immunosuppression, phenylketonuria Number completing study: 45/45 (100%) probiotic and 52/52 (100%) placebo
Interventions	LiveL. GG ATCC 53103 (10¹⁰ organisms in 250 mL ORF). ORF administered at 100 mL/kg over first 4 hours. Then either IV fluids or 10‐15 mL/kg ORF per liquid/semi‐solid stool. ORF with placebo. Start time for administration unclear.
Outcomes	Stool frequency, character Volume and length of use of ORF Duration of diarrhoea (until 2 consecutive normal stools) Use of antibiotics after recruitment No comment regarding adverse events.
Notes	Study location: Europe, Egypt, Africa, and single site (Montevideo) in S. America (variable child and adult mortality) Cause of diarrhoea: bacterial pathogens: probiotic group 29 (64.4%) and placebo group 37 (71.2%); rotavirus: probiotic group 18 (40.0%) and placebo group 21 (40.4%); parasites: probiotic group 2 (4.4%) and placebo group 4 (7.7%); no pathogens identified: probiotic group 11 (24.4%) and placebo group 14 (26.9%). Nutritional status: 15 (33.3%) in the probiotic and 20 (38.5%) in the control group had at least some malnutrition. Hydration status: mild/moderate dehydration in 15 (33.3%) probiotic and 17 (32.7%) control group. Severer dehydration in 0 in the probiotic and 2 (3.8%) control group. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Alternate allocation
Allocation concealment?	High risk	Alternate allocation
Blinding?   All outcomes	Unclear risk	Not described
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 3 centres Duration: not stated
Participants	Inclusion criteria: inpatients; infants and children with 3 or more loose stools within 24h period of < 72 hours duration Exclusion criteria: history of acute diarrhoea within 14 days preceding the inclusion in the study; antibiotic treatment; received probiotic up to 7 days before the participation in the study; exclusively breast fed; chronic alimentary disease; diagnosis of malabsorption; lack of parental consent; lack of diarrhoea. Number completing study: 86/87 (98.9%) probiotic group and 87/89 (97.8%) placebo group.
Interventions	L. acidophilus, B. bifidum, L. bulgaricus (3.2 x 10⁹ CFU/day for 5 days) identical placebo (no details given) Interventions administered from recruitment.
Outcomes	Duration of diarrhoea (defined as time to last loose stool) Duration of diarrhoea in rotavirus positive children Diarrhoea severity Vomiting Weight gain Duration of hospital stay Mean duration of diarrhoea reported for children with rotavirus diarrhoea. No adverse effects attributed to probiotic.
Notes	Study location: Poland (low child and adult mortality) Cause of diarrhoea: rotavirus identified in 31 (37.3%) probiotic and 22 (26.8%) placebo group. Bacterial pathogens identified in 6 (7.2%) probiotic and 14 (17%) placebo group. Nutritional status: no data presented. Hydration status: no data presented. Source of funding: interventions provided by Allergon, Sweden
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Allocated according to order of presentation
Allocation concealment?	High risk	Allocated according to order of presentation
Blinding?   All outcomes	Low risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

PERMALINK

Probiotics for treating acute infectious diarrhoea

Stephen J Allen

Elizabeth G Martinez

Germana V Gregorio

Leonila F Dans

Abstract

Background

Objectives

Search methods

Selection criteria

Data collection and analysis

Main results

Authors' conclusions

Plain language summary

Background

Definition

Incidence and disease burden

Causes

Treatment

Probiotics

Objectives

Methods

Criteria for considering studies for this review

Types of studies

Types of participants

Types of interventions

Intervention

Control

Types of outcome measures

Primary

Secondary

Search methods for identification of studies

Data collection and analysis

Study selection

Assessment of methodological quality

Data extraction

Data analysis

Results

Description of studies

Publication status

Study location

Participants

Interventions

Risk of bias in included studies

Effects of interventions

Primary outcomes

1.1. Analysis.

1.2. Analysis.

1.3. Analysis.

1.

2.

3.

Secondary outcomes

2.1. Analysis.

2.2. Analysis.

Exploration of heterogeneity

Sensitivity analysis for primary outcomes

1. Heterogeneity in sensitivity analysis of primary outcomes1.

3.1. Analysis.

3.2. Analysis.

3.3. Analysis.

4.1. Analysis.

4.2. Analysis.

4.3. Analysis.

5.1. Analysis.

6.1. Analysis.

6.2. Analysis.

6.3. Analysis.

7.1. Analysis.

7.2. Analysis.

8.1. Analysis.

9.1. Analysis.

9.2. Analysis.

9.3. Analysis.

Probiotic organisms; strain, single organisms versus combinations and dose

Age of participants

Children with rotavirus diarrhoea

Bacterial diarrhoea

Adverse events

1. Heterogeneity in sensitivity analysis of primary outcomes¹.

Methods	Randomized controlled trial, non‐blinded; 1 centre Duration: 6 months, October 1999 to March 2000
Participants	Inclusion criteria: inpatients; consecutive admissions aged 6‐60 months; diarrhoea < 5 days and > 3 watery stools in last 24 hours. Average dehydration about 5% in both groups. Exclusion criteria: bloody stools, antidiarrhoeal or antiperistaltic drugs; children receiving lactose‐free, protein hydrolysated formula for malabsorptive disorder; compromised immune system. Number completing study: 50/50 (100%) probiotic and 50/50 (100%) control group.
Interventions	Lyophilized L. acidophilus and Bifidobacteria infantis (Infloran Berna; 3 x 10⁹ of each organism/day for 4 days) No additional treatment All children had IV fluids because of vomiting. Interventions administered after initial fluid therapy.
Outcomes	Stool frequency by day of intervention Duration of diarrhoea (time until the last watery stool) Recovery rate on day 2 No comment regarding adverse effects.
Notes	Study location: Taiwan (low child and adult mortality). Cause of diarrhoea: bloody diarrhoea excluded. Nutritional status: no data presented. Hydration status: % average dehydration 4.3 (SD 1.5) in probiotic and 4.0 (1.4) in control group. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Unclear risk	Probably open study; no placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 1centre Duration: 6 months, October 2004 to March 2005
Participants	Inclusion criteria: inpatients and outpatients; previously healthy children; aged 6 months to 10 years; acute diarrhoea (not defined). Exclusion criteria: severe systemic infection or sepsis; chronic disease; previous antibiotics; anti‐diarrhoeal drugs; primary/secondary immune deficiency. Number completing study: 16/16 (100%) for the probiotic group. 11/11(100%) for the control group.
Interventions	S. boulardii (500 mg/day in 5 mL of water for 7 days) Placebo Start of intervention unclear.
Outcomes	Number, characteristics and frequency of stools; Blood tests (blood count and lymphocyte subsets, C‐reactive protein, blood smear, complement, immunoglobulins and cytokines). No adverse events attributed to probiotic.
Notes	Study location: Turkey (low child, low adult mortality) Cause of diarrhoea: 1 (6.3%) child in probiotic and 0 in control group had bacterial diarrhoea. Nutritional status: mild/moderate malnutrition in 2 (12.5%) in the probiotic and 1 (9.1%) in the control group. Hydration status: severe dehydration in 1 (6.3%) in the probiotic and 0 in the control group; mild/moderate dehydration in 3 (18.8%) in the probiotic and 2 (18.2%) in the control group. Source of funding: Sanofi‐Aventis (Paris, France) provided laboratory reagents and a commercial preparation of S. boulardii
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Low risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up ≥ 90% in both groups

Methods	Randomized controlled trial; 2 centres Duration: 6 months, December 1998 to May 1999
Participants	Inclusion: inpatients; children aged 6 to 36 months with 2 or more consecutive loose stools in 24 hours and a duration no more than 7 days. Exclusion criteria: underlying chronic disease or antibiotics prescribed during the study period. Number completing study: 86 children enrolled, of whom 69 (80.2%) completed the study; exclusions were made after randomization because antibiotics were prescribed (3 in the control group and 2 in the probiotic group), rapid recovery before intervention started (3 in the control group and one in the probiotic group), non‐compliance with the protocol (4 in the control group and 4 in the probiotic group).
Interventions	Live L. rhamnosus 19070‐2 and L. reuteri DSM 12246 (2 x 10⁹ CFU of each organism/day for 5 days) Identical placebo (skimmed milk powder and dextrose anhydrate) Interventions started as soon as possible after randomization and did not await rehydration.
Outcomes	Duration of diarrhoea (time from treatment start to appearance of first normal stool as recorded by parents). Persistence of diarrhoea at end of intervention (day 5). No adverse events attributed to probiotic.
Notes	Study location: Denmark (very low child and adult mortality). Cause of diarrhoea: overall, rotavirus was the only pathogen in 40 (58%) children; 6 children had rotavirus and a bacterial pathogen was identified; in addition, Campylobacter jejuni was isolated in 3 children and Salmonella typhimurium in 1 child. Nutritional status: no data presented. Hydration status: no severe dehydration; mild/moderate dehydration in 5 (16.7%) in the probiotic and 17 (43.6%) in the control group. The probiotics appeared to reduce significantly the duration of diarrhoea in children treated within 60 hours of the onset of diarrhoea. Hospital stay was shorter in the probiotic group than the controls (mean 1.6 (SD 1.0) versus 2.7 (SD 2.0) respectively; P = 0.02). The probiotics also appeared to reduce significantly the number of children excreting rotavirus in stools on day 5. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Low risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	High risk	Follow up < 90% in both groups

Methods	Randomized controlled trial; 19 day‐care centres Duration: 6 months, December 1998 to May 1999
Participants	Inclusion criteria: outpatients; children aged 6 to 36 months with 2 or more consecutive loose stools in 24 hours as assessed by parents and with a duration no more than 7 days. Exclusion criteria: underlying chronic disease; antibiotics prescribed during study period. Number completing study: 50 children enrolled, of whom 43 (86%) participants completed the study. Exclusions were because of hospitalization with excessive vomiting and moderate dehydration (2 in the placebo group and 3 in the probiotic group), 1 because antibiotics were prescribed (placebo group), 1 non‐compliant with protocol (placebo group).
Interventions	Live L.rhamnosus 19070‐2 and L. reuteri DSM 12246 (2 x 10⁹ CFU of each organism/day for 5 days) Identical placebo Interventions started as soon as possible after randomization.
Outcomes	Duration of diarrhoea (time from treatment start to appearance of first normal stool as recorded by parents). Persistence of diarrhoea at end of intervention (day 5). One participant in the probiotic group complained of constipation (no stools passed from day 3 for 10 days). No adverse events attributed to probiotic.
Notes	Study location: Denmark (very low child and adult mortality). Cause of diarrhoea: overall, rotavirus was the only pathogen in 25 children, 2 had rotavirus and a bacterial pathogen identified, 2 had an infection with C. jejuni and Salmonella typhimurium. Nutritional status: no data presented. Hydration status: mild/moderate dehydration in 3 patients (12.5%) in the probiotic and 4 (13.8%) in the control group; no severe dehydration. The probiotics appeared to reduce significantly the duration of diarrhoea in children treated within 60 hours of the onset of diarrhoea. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Low risk	Identical placebo
Incomplete outcome data addressed?   All outcomes	High risk	Follow up < 90% in both groups

Methods	Randomized trial; 1 centre Duration: 1 year; November 1992 to October 1993
Participants	Inclusion criteria: inpatients; infants and children with ≥2 loose stools for 1 to 3 days or haemorrhagic colitis, fever ≥ 38.0^oC,or second stage dehydration, or both. All had shigellosis. Exclusion criteria: not stated Number completing study: 13/13 (100%) children in the probiotic group and 12/12 (100%) in the control group.
Interventions	L. casei strain GG (10^10‐11 CFU/day for either 5 or 10 days) + trimethoprim‐sulfamethoxazole (36 mg/kg/day for 5 days) trimethoprim‐sulfamethoxazole (36 mg/kg/day for 5 days) When interventions started was not stated.
Outcomes	Number cured (defined as < 2 loose stools/24 hours without additional clinical symptoms for at least 3 days) Duration of diarrhoea Duration of hospital stay No comment regarding adverse effects
Notes	Study location: Estonia (low child, high adult mortality) Cause of diarrhoea: all shigellosis. 9 (69.2%) in the probiotic and 4 (33.3%) in the controls had bloody diarrhoea. Nutritional status: no data presented. Hydration status: no data presented. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	High risk	No placebo; probably open study
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up > 90% in both groups

Methods	Quasi‐randomized controlled trial; 1 centre Duration: not stated
Participants	Inclusion criteria: inpatients; infants and children with acute rotavirus diarrhoea (stool characteristics described for each participant; stool frequency x 1‐10/day; duration not stated); none had bloody stools. Exclusion criteria: none stated. Number completing study: 16/17 (94.1%) in the probiotic group and 11/15 (73.3%) in the control group.
Interventions	Live L. casei (1.5 g/day for up to 3 weeks) No additional treatment Not stated when interventions started. All participants received lactase (1.5 g/day in 3 doses) and albumin tannate (0.1/kg/day in 3 doses).
Outcomes	Efficacy, as judged by a clinician Time to first formed stool Average stool frequency before and after treatment Persistence of stool rotavirus antigen 1 week after intervention No adverse events attributed to probiotic.
Notes	Study location: Japan (very low child and adult mortality). Cause of diarrhoea: all rotavirus diarrhoea. Nutritional status: no data presented. Hydration status: no data presented. Results for time to first formed stool given for 16/17 (94.1%) participants in the probiotic group and 11/15 (73.3%) in the control group. Reasons for missing data not stated. Rotavirus antigen persisted in the stools of 1/9 (11.1%) children in the probiotic group and 2/8 (25%) in the control group. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	High risk	Allocation in order of hospitalization
Allocation concealment?	High risk	Allocation in order of hospitalization
Blinding?   All outcomes	High risk	Open study
Incomplete outcome data addressed?   All outcomes	High risk	Overall < 90% follow up in placebo group

Methods	Randomized, single blind controlled trial; 1 centre Duration: 7 months; August 2007 to February 2008
Participants	Inclusion criteria: inpatients; infants and children with a history of acute watery diarrhoea (defined as ≥3 stools of liquid consistency/day < 72 hours duration) positive for rotavirus and with moderate to severe dehydration. Exclusion criteria: severe malnutrition; systemic infections requiring antibiotic therapy; severe chronic disease; identification of a second pathogen in the stool; ingestion of antibiotics; probiotics or nitazoxanide 3 weeks before admission; recurrence of diarrhoea after discharge. Patients in whom a cause of diarrhoea other than rotavirus were withdrawn (probiotic group: 3 with adenovirus, 2 with E. histolytica; control group: 3 with E. histolytica, 2 with Giardia, 1 with S. flexneri). Number completing study: 25/25 (100%) probiotic group; 25/25 (100%) control group.
Interventions	Participants were allocated to one of three groups: a nitazoxanide, a probiotic and a control group that received rehydration solutions only. Data from the probiotic group and controls used for this review. L. acidophilus, L. rhamnosus, B.longum, S. boulardii (total of 2.5 x 10⁹ organisms/day administered for an average of 4.2 days). Unclear if they were live or killed organisms. Control (ORF only) Time when interventions started not described.
Outcomes	Duration of diarrhoea (time from admission until the presence of the first soft stool for at least 24 hours) Stool number and consistency Duration of fever Vomiting Duration of hospitalization No adverse events attributed to probiotic.
Notes	Study location: Bolivia (high child and high adult mortality) Cause of diarrhoea: all rotavirus diarrhoea. Nutritional status: severe malnutrition excluded; mild/moderate malnutrition in 5 (20%) in the probiotic and 15 (60%) in the control group. Hydration status: all had moderate to severe dehydration; no further data presented. Source of funding: the research was not sponsored by any pharmaceutical company
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Low risk	Computerised admissions list
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	High risk	Single blind; only parents/caretakers not aware of group allocation. No placebo.
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up > 90% in both groups

Methods	Randomized trial; 1 centre Duration: 1994‐1995
Participants	Inclusion criteria: inpatients; infants and children Exclusion criteria: nosocomial rotaviral infection Number completing the study: 50/50 (100%) probiotic group; 50/50 (100%) control group.
Interventions	Live L. acidophilus ND (4 x 10⁹ bacteria/day; duration not stated) Standard treatment Time when interventions started:
Outcomes	Average number of stools/day stool consistency at 5 days No adverse events attributed to the probiotic.
Notes	Study location: Czech Reublic (very low child and adult mortality) Cause of diarrhoea: nosocomial rotavirus diarrhoea excluded; 16 (32.0%) probiotic and 21 (42.0%) control group had viral diarrhoea. A total of 22 (44.0%) in the probiotic and 24 (48.0%) in the control group had bacterial diarrhoea. Nutritional status: no data presented. Hydration status: severe dehydration in 3 (6.0%) probiotic and 2 (4.0%) in the control group; all the rest had mild/moderate dehydration. No data presented that could be extracted for meta‐analysis. Source of funding not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	High risk	No placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up > 90% in both groups

Methods	Randomized open study; 1 centre Duration: March 2003 to January 2004; 11 months
Participants	Inclusion criteria: inpatients and outpatients; infants and children with watery diarrhoea (not defined) for < 5 days. Exclusion criteria: immunocompromised; suspected dysentery; diagnosed with persistent or chronic diarrhoea; chronic cardiac, pulmonary or haematological illness; undergoing antibiotic treatment in the last 2 weeks; severe dehydration or shock. 4/75 withdrawn (1 febrile seizure, 1 urinary tract infection, 2 with pneumonia). Two patients were withdrawn from each group. Number completing study: 36/38 (94.7%) in the probiotic group; 35/37 (94.6%) in the control group.
Interventions	Live L. acidophilus, Bifidobacterium infantis (Infloran; 6 x 10⁹ CFU/day for 2 days) Control group did not receive probiotic Timing of administration not stated
Outcomes	Duration of diarrhoea Weight change/day Number bowel motions on day 2 Vomiting Duration of hospitalization Duration of diarrhoea reported for rotavirus diarrhoea. No adverse events attributed to probiotic.
Notes	Location: Thailand; low child and adult mortality Cause of diarrhoea: suspected dysentery excluded; overall, 34% had rotavirus and 12.1% Salmonella in stools. Nutritional status: no data presented. Hydration status: severe dehydration excluded; mild/moderate dehydration in 25 (69.4%) probiotic and 23 (65.7%) control group. Source of funding: AIS donation fund, Thai Red Cross Society
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	High risk	Open study; no placebo
Incomplete outcome data addressed?   All outcomes	Low risk	Follow up > 90% in both groups

Methods	Randomized controlled trial; 10 centres Duration: not stated
Participants	Inclusion criteria: adults with acute diarrhoea (characteristics and duration not stated). Exclusion criteria: not stated. 3 participants from each group withdrawn on day 4 or later (causes for dropouts stated to be unrelated to medication); 4 participants assigned to the probiotic group and 5 assigned to the placebo group did not complete the study (reasons not stated). Number completing study (for persisting diarrhoea outcomes): 40/47 (85.1%) in the probiotic group and 38/46 (82.6%) in the placebo group.
Interventions	Live Enterococcus SF 68 (Bioflorin; 225 x 10⁶ bacteria/day for 7 days) Placebo Not stated when interventions started.
Outcomes	Number of cases cured by day of treatment (definition of cure not stated). No adverse events attributed to probiotic.
Notes	Study location: Switzerland and Lichtenstein (very low child and adult mortality). Cause of diarrhoea: no data presented. Nutritional status: no data presented. Hydration status: no data presented. Source of funding: not stated
*Risk of bias*
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not described
Allocation concealment?	Unclear risk	Not described
Blinding?   All outcomes	Low risk	identical placebo
Incomplete outcome data addressed?   All outcomes	High risk	Follow up <90% in both groups