Abstract
Clostridioides difficile infection is a significant public health challenge. This study aimed to determine the overall prevalence of C. difficile contamination in healthcare and non-healthcare environments around the world from 2014 to 2024. In this systematic review, we searched five international databases. Random and fixed-effects models were used to estimate the pooled prevalence with 95% CIs. Among the 49 eligible studies and 20 779 environmental samples, 4507 samples were positive for C. difficile contamination. The overall prevalence was estimated as 0.26 (95% CI 0.23 to 0.28). The pooled prevalence according to the detection method was 0.26 (95% CI 0.21 to 0.32) and 0.62 (95% CI 0.50 to 0.74) using a culture test and PCR, respectively. The overall prevalence was 0.18 (95% CI 0.16 to 0.20) and 0.36 (95% CI 0.30 to 0.42) in the healthcare and non-healthcare environment, respectively. The prevalence in non-healthcare environments was 0.42, 0.38, 0.33 and 0.04 on farms, in public places, in the home and veterinary hospitals, respectively. The findings reveal a significant prevalence of C. difficile contamination across various environments worldwide. This alarming trend underscores the pressing need to prioritize environmental factors and implement effective disinfection strategies as part of comprehensive control programs aimed at tackling this disease.
Keywords: Clostridium difficile, environment, healthcare, prevalence, systematic review
Introduction
Clostridium difficile or Clostridioides difficile is an anaerobic Gram-positive bacterium that is found as a flora of healthy infants. This bacterium can cause disease with severe diarrhea and inflammation of the colon or colitis, and overuse of antibiotics facilitate its occurrence.1,2 The bacterium produces two exotoxins, toxin A (TcdA) and toxin B (TcdB), which are associated with the severity of the disease. Toxin A (308 kDa) causes inflammation, resulting in the secretion of intestinal fluids and colonic mucosal damage. Toxin B (270 kDa) also causes mucosal damage. Furthermore, C. difficile produces CD, including a cell binding component (CDTb) and an enzymatic component (CDTa) with ADP ribosyltransferase activity, leading to cytoskeleton disorganization. Other virulence factors include endospore, S-layers, flagella and fimbriae, as well as other virulence factors.3
The occurrence of the disease known as C. difficile infection (CDI) is associated with clinical symptoms that include watery diarrhea, abdominal pain, dehydration, fever, nausea and weight loss. In other words, the disease can cause a range of gastrointestinal issues from mild to severe that can be life-threatening.4 Considering the importance of the disease, Centers for Disease Control and Prevention (CDC) classified CDI as an urgent public health issue in 2013; there were 250 000 infections and 14 000 deaths reported by the CDC in 2013. The crude incidence rate of CDI was reported as 130.28 per 100 000 persons by the CDC in the CDI Surveillance report in 2017. According to the latest update of the report, the crude incidence rate of CDI in 2022 was 116.1 cases per 100 000 persons.5
It has been proven that, besides asymptomatic carriers, the environment plays a crucial role in the transmission of CDI, particularly within healthcare settings. Contaminated surfaces in hospitals can harbor C. difficile spores, which are highly resistant to environmental stressors and can persist for months or even years. These spores can be transferred to patients through direct contact with contaminated surfaces or via healthcare workers, contributing to the spread of infection. Enhanced cleaning protocols, including the use of sporicidal disinfectants, are essential to mitigate the risk.6,7
To date, several researchers have reported the contamination rate in various healthcare and non-healthcare environmental settings. Despite this, no attempt has been made to summarize the reported contamination rate worldwide in recent years. Therefore, to fill this gap and improve our understanding of the current global prevalence of contamination, this study was conducted to evaluate the overall prevalence of C. difficile contamination in both healthcare and non-healthcare environments in the last decade (2014–2024).
Methods
Search strategy
We conducted a global systematic review by searching five international databases, namely, PubMed, Science Direct, Springer, CABI Direct and Google Scholar. The search covered the period from January 2014 to January 2024 and utilized the following keywords: ‘Clostridium spp.’, ‘difficile AND environment’, ‘difficile AND healthcare’, ‘difficile AND equipment’ and ‘difficile AND public’. We searched for these combinations in the titles, keywords and abstracts of published papers in the aforementioned databases. The study protocol was registered in the open science framework (OSF) registries for systematic reviews with the following doi: https://doi.org/10.17605/OSF.IO/G8BTQ.
Study selection process
Studies with insufficient data, irrelevant and duplicated data were excluded from the analysis. Scientist evaluated studies related to C. difficile contamination by screening their titles and abstracts, then reviewed the full text of papers for quality assessment after eliminating duplicates. In addition, the references of eligible papers were searched to find additional eligible articles. Scientist conducted separate assessments of the articles' quality.
Eligibility criteria
Articles were considered eligible if they met the following inclusion criteria: (i) they were conducted on environmental samples; and (ii) they reported the prevalence of C. difficile contamination. However, papers that met the following criteria were excluded from the analysis: (i) they were conducted before 2014; (ii) they did not report the prevalence of C. difficile contamination; or (iii) they were case reports or experimental studies.
Data extraction
The investigators used a form specifically designed to extract data from eligible papers. Data from the papers were extracted into summary tables containing information on author(s) name(s), publication year, detection methods, country, region, setting, sample type, total number of samples and the total number of confirmed C. difficile samples.
Quality assessment
The authors reviewed eligible research articles using Critical Appraisal Skills Programme (CASP) Checklists to evaluate cross-sectional studies. This tool has special items to evaluate the quality of a paper, using 10–12 items for each checklist. These checklists evaluate the strengths and weaknesses of articles, the quality of the study design and the applicability of studies. The precise checklist was applied to each paper according to the type of study. For each item, the possible answers were ‘Yes’, ‘No’ or ‘Can’t tell’. Scientist assessed the articles’ quality separately, and discrepancies were resolved via group discussion. For each item, an answer of ‘Yes’ was scored as 1, while answers of ‘No’ or ‘Can’t tell’ were set as 0. Therefore, the maximum score of cross-sectional studies in this systematic review was 11. Articles with scores of ≥75% of the total score were classified as good quality. Articles with scores of 25–75% of the total score were classified as moderate quality articles and articles with scores of <25% of the total score were classified as poor quality articles.8
Statistical analysis
We employed both random and fixed-effects models to calculate the pooled prevalence and 95% CIs. To evaluate heterogeneity among the studies, we utilized Cochran’s Q test and the I2 index. A random-effects model was selected for estimation when the I2 index was >50% and the p-value from Cochran’s Q test was <0.1. Forest plots illustrate the proportions of individual studies, the pooled prevalence and the heterogeneity across studies. The meta-analysis was performed using Stata version 14.
Results
Search results and eligibility
Initially, 3678 articles were obtained from the electronic database search. However, 3629 (98.86%) were excluded due to irrelevancy, duplicated documents, lack of access to the full text or insufficient data. Finally, 49 (1.33%) were deemed eligible and subjected to analysis.6–54 A flowchart illustrating the screening of papers is presented in Figure 1. Extracted data from studies included in the meta-analysis (up to 1 January 2024) are presented in Table 1.
Figure 1.
PRISMA flowchart presenting the selection of articles analyzed in this systematic review and meta-analysis. PRISMA: Preferred Reporting Items for Systematic reviews and Meta-Analyses.
Table 1.
Characteristics of the studies included in the meta-analysis
| Study number | First author | Year | Country | Setting | Diagnostic methods | Sample size number | Positive number | Reference |
|---|---|---|---|---|---|---|---|---|
| 1 | Aliramezani | 2019 | Iran | Healthcare | Culture/other test | 1435 | 2 | 9 |
| 2 | Büchler | 2022 | Switzerland | Healthcare | Culture/other test | 206 | 37 | 10 |
| 3 | Doughari | 2021 | Nigeria | Healthcare | Culture | 150 | 18 | 11 |
| 4 | Islam | 2019 | Bangladesh | Non-healthcare | Culture | 94 | 11 | 12 |
| 5 | Janezic | 2018 | Slovenia | Non-healthcare | Culture/other test | 90 | 31 | 13 |
| 6 | Janezic | 2020 | Slovenia | Non-healthcare | Culture | 25 | 12 | 14 |
| 7 | Jinhee | 2022 | USA | Healthcare and non-healthcare | - | 6966 | 1794 | 15 |
| Mexico, Peru, Guatemala, Brazil, France, Germany, Italy, Taiwan, India | Non-healthcare | - | 891 | 194 | ||||
| 8 | Kabała | 2022 | Poland | Healthcare | Culture/other test | 116 | 6 | 16 |
| 9 | Kiersnowska | 2022 | Poland | Healthcare | Culture | 116 | 6 | 17 |
| 10 | Lemiech-Mirowska | 2023 | Poland | Healthcare | Culture | 100 | 7 | 18 |
| 11 | Lim | 2020 | Australia | Healthcare | Culture | 302 | 159 | 19 |
| 12 | Perumalsamy | 2019 | Australia | Healthcare | Culture | 159 | 96 | 20 |
| 13 | Reigadas | 2020 | Spain | Healthcare | Culture/other test | 476 | 73 | 21 |
| 14 | Riley | 2018 | Australia | Non-healthcare | PCR | 145 | 86 | 22 |
| 15 | Shivaperumal | 2021 | Australia | Non-healthcare | Culture | 97 | 65 | 23 |
| 16 | Rodriguez | 2019 | Belgium | Non-healthcare | Culture/other test | 112 | 45 | 24 |
| 17 | Sofjan | 2020 | Bangladesh | Healthcare | Culture | 400 | 44 | 25 |
| 18 | Srinivasa | 2019 | USA | Healthcare | Culture/other test | 101 | 14 | 26 |
| 19 | Villagomez-Estrada | 2019 | Spain | Non-healthcare | Culture/other test | 100 | 4 | 27 |
| 20 | Weppner | 2021 | USA | Healthcare | Culture | 76 | 17 | 28 |
| 21 | Zhou | 2021 | China | Healthcare | Culture | 608 | 12 | 29 |
| 22 | Blau | 2023 | Germany | Non-healthcare | Culture and other test | 79 | 30 | 30 |
| 23 | O’Shaughnessy | 2019 | Canada | Non-healthcare | Culture/other test | 350 | 144 | 31 |
| 24 | Simecka | 2019 | USA | Healthcare | Culture/other test | 630 | 24 | 32 |
| 25 | Khun | 2023 | Vietnam | Healthcare and non-healthcare | Culture | 199 | 65 | 33 |
| 26 | Warren | 2022 | USA | Healthcare | Culture | 758 | 121 | 34 |
| 27 | Lim | 2022 | Australia | Healthcare | Culture | 600 | 185 | 35 |
| 28 | Endres | 2018 | USA | Healthcare | Culture/other test | 50 | 14 | 36 |
| 29 | Tsai | 2022 | Taiwan | Non-healthcare | Culture/other test | 29 | 7 | 37 |
| 30 | Moradigaravand | 2018 | UK | Non-healthcare | Culture/other test | 20 | 18 | 38 |
| 31 | Garey | 2020 | USA | Healthcare | Culture | 659 | 55 | 39 |
| 32 | Shoaei | 2019 | Iran | Healthcare | Culture/other test | 92 | 9 | 40 |
| 33 | Odoyo | 2020 | Kenya | Healthcare | Culture | 57 | 43 | 41 |
| PCR | 57 | 43 | ||||||
| 34 | Brown | 2018 | Canada | Healthcare | PCR | 96 | 50 | 42 |
| Culture | 48 | 21 | ||||||
| 35 | Moono | 2017 | Australia | Non-healthcare | Culture/other test | 311 | 182 | 43 |
| 36 | Alam | 2017 | USA | Healthcare and non-healthcare | - | 2538 | 418 | 44 |
| 37 | Orden | 2018 | Spain | Non-healthcare | Culture/other test | 40 | 21 | 45 |
Table 1.
Continued
| Study number | Author | Year | Country | Setting | Diagnostic methods | Sample size number | Positive number | Reference |
|---|---|---|---|---|---|---|---|---|
| 38 | Taha | 2022 | Egypt | Non-healthcare | Culture | 200 | 38 | 46 |
| 39 | Alves | 2022 | Portugal | Non-healthcare | Culture/other test | 60 | 35 | 47 |
| 40 | Redding | 2021 | USA | Non-healthcare | Culture/other test | 92 | 28 | 48 |
| 41 | Usui | 2017 | Japan | Non-healthcare | Culture/other test | 14 | 5 | 49 |
| 42 | Marcos | 2021 | Ireland | Non-healthcare | Culture/other test | 180 | 68 | 50 |
| 43 | Alam | 2014 | USA | Non-healthcare | Culture/other test | 127 | 41 | 51 |
| 44 | Leitner | 2020 | Austria | Healthcare | Culture | 92 | 0 | 52 |
| 45 | Ali | 2021 | India | Non-healthcare | Culture/other test | 6 | 1 | 53 |
| 46 | Lim | 2020 | Australia | Non-healthcare | - | 142 | 32 | 54 |
| 47 | Janezic | 2016 | Slovenia | Non-healthcare | Culture/other test | 183 | 44 | 55 |
| 48 | Baghani | 2020 | Iran | Non-healthcare | Culture/other test | 72 | 1 | 56 |
| 49 | Shaughnessy | 2016 | USA | Non-healthcare | Culture/other test | 233 | 31 | 57 |
Characteristics of eligible studies
In general, 49 studies measured C. difficile contamination in healthcare and non-healthcare settings. Among these, 25 (51.02%) measured contamination in healthcare settings. Non-healthcare settings consisted of farms, public places, homes and veterinary hospitals. Of the 49 eligible studies, 21 (42.85%) were published before 2020. Based on WHO regions, two were conducted in Africa, while 13, 16, four, three and 11 were conducted in America, Europe, Eastern Mediterranean, South-East Asia and Western Pacific, respectively.
Quality of the eligible studies
Of the 49 original articles, considering the total CASP scores, 31 (63.26%) met all the approval criteria; 46 (93.87%) were classified as good quality and three (6.13%) were classified as moderate quality. No articles were classified as being of poor quality.
Prevalence of C. difficile contamination
Overall, 20 779 environmental samples were investigated in healthcare and non-healthcare settings. Among these, 4507 samples were positive for C. difficile contamination using different detection methods. Meta-analysis indicated that the pooled prevalence of C. difficile contamination using random effects was estimated as 0.26 (95% CI 0.23 to 0.28). There was a high degree of heterogeneity in the prevalence estimates between different studies. It was observed that the Q statistic was 6767.31 (df=48), p<0.01 and I2=99.29% (Table 2 and Figure 2).
Table 2.
Pooled prevalence of C. difficile contamination in healthcare and non-healthcare environments
| Total | Heterogeneity | Heterogeneity | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Number | Sample | Number | Pooled | between | |||||
| Independent variable | of studies | size | positive | prevalence | 95% CI | Q statistic | I2 (%) | p | subgroup bias |
| Diagnostic test | |||||||||
| Culture | 19 | 4740 | 975 | 0.26 | 0.21–0.32 | 1709.52 | 98.95 | 0.00 | 0.00 |
| Culture and other test | 26 | 5204 | 915 | 0.27 | 0.21–0.33 | 1655.63 | 98.49 | 0.00 | |
| PCR | 3 | 298 | 179 | 0.62 | 0.50–0.74 | 0 | 0 | 0.00 | |
| Region | |||||||||
| Africa | 2 | 264 | 104 | 0.31 | 0.27–0.36 | - | - | - | 0.00 |
| Eastern Mediterranean | 4 | 1799 | 50 | 0.07 | 0.01–0.13 | 56.58 | 94.70 | 0.00 | |
| America | 13 | 12 724 | 2772 | 0.23 | 0.17–0.29 | 813.01 | 98.52 | 0.00 | |
| South-East Asia | 3 | 500 | 56 | 0.11 | 0.08–0.14 | - | - | - | |
| Western Pacific | 11 | 2606 | 894 | 0.41 | 0.23–0.58 | 1365.82 | 99.27 | 0.00 | |
| Europe | 16 | 1995 | 437 | 0.28 | 0.20–0.36 | 815.86 | 98.16 | 0.00 | |
| Year | |||||||||
| Before 2020 | 21 | 6968 | 1311 | 0.31 | 0.25–0.38 | 2294.83 | 99.13 | 0.00 | 0.11 |
| After 2020 | 28 | 13 811 | 3196 | 0.24 | 0.19–0.30 | 4415.21 | 99.39 | 0.00 | |
| Setting | |||||||||
| Healthcare | 25 | 11 475 | 1962 | 0.18 | 0.16–0.20 | 2929.39 | 99.18 | 0.00 | 0.00 |
| Non-healthcare | 30 | 9304 | 2545 | 0.36 | 0.30–0.41 | 1157.38 | 97.49 | 0.00 | |
| Sample type | |||||||||
| Soil | 8 | 530 | 310 | 0.59 | 0.47–0.71 | 60.19 | 88.37 | 0.00 | 0.00 |
| Shoe | 8 | 2084 | 813 | 0.34 | 0.23–0.45 | 156.27 | 95.52 | 0.00 | |
Figure 2.
Forest plot of the pooled prevalence of C. difficile contamination in healthcare and non-healthcare environments.
According to diagnostic method, the pooled prevalence of C. difficile contamination by culture test was 0.26 (95% CI 0.21 to 0.32). The pooled prevalence using PCR was 0.62 (95% CI 0.50 to 0.74). Meanwhile, the pooled prevalence using a mixed method was 0.27 (95% CI 0.21 to 0.33) (Table 2 and Figure 3).
Figure 3.
Forest plots of the pooled prevalence of C. difficile contamination in healthcare and non-healthcare environments according to (A) diagnostic test, (B) setting and (C) year.
The pooled prevalence of C. difficile contamination was 0.31 (95% CI 0.25 to 0.38) and 0.24 (95% CI 0.19 to 0.30) before and after 2020, respectively (Figure 3).
The pooled prevalence of C. difficile contamination according to region indicated that the highest prevalence was in the Western Pacific with a prevalence of 0.41 (95% CI 0.23 to 0.58). The lowest prevalence was in the Eastern Mediterranean with a prevalence of 0.07 (95% CI 0.01 to 0.13). The pooled prevalence in the other regions was 0.40, 0.31, 0.23 and 0.11 in Europe, Africa, America and South-East Asia, respectively. Complete results by region are shown in Table 2 and Figure 4.
Figure 4.
Forest plot of the pooled prevalence of C. difficile contamination in healthcare and non-healthcare environments according to region.
The pooled prevalence of C. difficile contamination according to setting was 0.18 (95% CI 0.16 to 0.20) in the healthcare environment and 0.36 (95% CI 0.30 to 0.42) in the non-healthcare environment (Figure 3).
The pooled prevalence of C. difficile contamination according to sample type was 0.59 (95% CI 0.47 to 0.71) in soil samples and 0.34 in shoe samples (95% CI 0.32 to 0.45).
Prevalence of C. difficile contamination in healthcare environments
In total, among 11 475 environmental samples in healthcare settings, 1962 were positive for C. difficile contamination. The pooled prevalence of C. difficile contamination among environmental samples in healthcare settings was 0.18 (95% CI 0.16 to 0.20).
The pooled prevalence of C. difficile contamination in healthcare environments according to region indicated that the highest prevalence was found in the Western Pacific (0.33; 95% CI 0.10 to 0.56), followed by Africa (0.31; 95% CI 0.27 to 0.36). The prevalence for all regions is shown in Table 3.
Table 3.
Pooled prevalence of C. difficile contamination in healthcare and non-healthcare environments
| Heterogeneity | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Independent variable | Number of studies | Sample size | Total number positive | Pooled prevalence | 95% CI | Q statistic | I2 (%) | p | Heterogeneity between subgroup bias |
| Healthcare | |||||||||
| Region | |||||||||
| Africa | 2 | 264 | 104 | 0.31 | 0.27–0.36 | - | - | - | 0.00 |
| Eastern Mediterranean | 2 | 1527 | 11 | 0.00 | 0.00–0.00 | - | - | - | |
| America | 9 | 6359 | 1193 | 0.19 | 0.12–0.26 | 449.47 | 98.22 | 0.00 | |
| South-East Asia | 1 | 400 | 44 | 0.11 | 0.08–0.14 | - | - | - | |
| Western Pacific | 5 | 1819 | 481 | 0.33 | 0.10–0.56 | 695.26 | 99.42 | 0.00 | |
| Europe | 6 | 1106 | 129 | 0.08 | 0.02–0.15 | 149.67 | 96.66 | 0.00 | |
| Sample type | |||||||||
| Bed | 7 | 447 | 43 | 0.09 | 0.04–0.15 | 53.52 | 88.79 | 0.00 | 0.00 |
| Chair | 2 | 246 | 16 | 0.03 | 0.01–0.05 | - | - | - | |
| Computer | 3 | 108 | 7 | 0.04 | 0.00–0.09 | - | - | - | |
| Door handle | 2 | 32 | 1 | 0.00 | 0.00–0.01 | - | - | - | |
| Light switch | 2 | 98 | 0 | 0.00 | 0.00–0.00 | - | - | - | |
| Shoe | 3 | 643 | 205 | 0.34 | 0.17–0.51 | - | - | - | |
| Soil | 2 | 189 | 121 | 0.66 | 0.59–0.73 | - | - | - | |
| Table | 3 | 76 | 9 | 0.10 | 0.03–0.17 | - | - | - | |
| Toilet or bathroom | 5 | 413 | 97 | 0.14 | 0.01–0.28 | 98.88 | 95.95 | 0.00 | |
| Wheelchair | 2 | 40 | 5 | 0.12 | 0.02–0.22 | - | - | - | |
| Window | 2 | 37 | 4 | 0.01 | 0.00–0.04 | - | - | - | |
| Non-healthcare | |||||||||
| Location | |||||||||
| Public | 16 | 6797 | 1869 | 0.38 | 0.28–0.48 | 705.04 | 98.01 | 0.00 | 0.00 |
| Home | 6 | 1607 | 345 | 0.33 | 0.20–0.45 | 138.87 | 96.32 | 0.00 | |
| Farm | 7 | 800 | 327 | 0.42 | 0.31–0.53 | 54.79 | 89.05 | 0.00 | |
| Veterinary hospital | 1 | 100 | 4 | 0.04 | 0.02–0.10 | - | - | - | |
The pooled prevalence of C. difficile contamination according to sample type indicated that the highest contamination rates were in soil and shoes, with a prevalence of 0.66 (95% CI 0.59 to 0.73) and 0.34 (95% CI 0.17 to 0.51), respectively. This was followed by toilet or bathroom with a prevalence of 0.14 (95% CI 0.01 to 0.28), then wheelchair with a prevalence of 0.12 (95% CI 0.02 to 0.22). Complete results due to the prevalence of various sample types in healthcare settings are shown in Table 3.
Prevalence of C. difficile contamination in non-healthcare environments
Overall, among 9304 non-healthcare environmental samples, 2545 were positive for C. difficile contamination. The pooled prevalence was 0.36 (95% CI 0.30 to 0.41). The prevalence in the non-healthcare environment according to location was 0.42, 0.38, 0.33 and 0.04 on farms, in public places, in the home and veterinary hospital, respectively.
Discussion
Clostridioides difficile is a Gram-positive, spore-forming anaerobic bacterium that is the cause of antibiotic-associated diarrhea, toxic megacolon and pseudomembranous colitis, which may be life-threatening.58 The bacterium is resistant to a wide range of bactericide substances due to the endospore, which can survive for months in harsh environments. This study is the first global comprehensive systematic review concerning C. difficile contamination in healthcare and non-healthcare environments and summarizes its prevalence over the last decade (2014–2024).
In the current study, the pooled prevalence of C. difficile contamination in all environmental samples was estimated as 0.26, but was different for various levels of other variables such as diagnostic test and setting. This result indicates the notable presence of C. difficile in diverse environments across the world in the last decade. On the other hand, research data suggest that C. difficile can persist on surfaces for months. Also, the bacterium has shown resistance to various chemical agents and disinfectants in recent years. Therefore, to effectively control CDI rates, it is crucial to implement a standardized surveillance program with attention paid to the role of the environment in the transmission of the disease. In recent years, more attention and effort have been dedicated to controlling CDI, especially healthcare-associated CDI, and some countries have established guidelines for the detection and control of infection. However, there is a need to implement these programs and guidelines on a global scale, taking account of the role of the environment in the spread of the disease.
Based on our results, the pooled prevalence was 0.31 (95% CI 0.25 to 0.38) and 0.24 (95% CI 0.19 to 0.30) before and after 2020, respectively, which indirectly shows the decrease in CDI cases in recent years. Research indicates that patients treated with certain antibiotics are less likely to contaminate their surroundings, demonstrating a direct link between infection management and environmental hygiene.59 Therefore, the decreased contamination rate in the environment in recent years can be attributed to implementing a control program of CDI in several countries, especially in the healthcare system. For example, there is increasingly promising evidence that CDI rates have declined in the healthcare systems of Europe and the USA that should be implemented in other countries.
Screening is an important method for disease control, for reducing symptoms and costs. Choosing screening-accurate tools to identify contaminated samples should be considered. Assessments of diagnostic testing, extracted from studies, were included in this study. Our results based on the diagnostic method utilized indicated that the pooled prevalence was an estimated 26% (95% CI 21 to 32%) using a culture test, approximately equal to those found with a culture test plus another method, attributable to other tests being used less than culture in a large number of studies, although it was an estimated 62% (95% CI 50 to 74%) for PCR only. Most studies found that the molecular-based method is more sensitive and more specific than the culture test; therefore, it appears that PCR is suitable for screening.
Our findings indicated a pooled prevalence of 18% within the healthcare system, whereas the pooled prevalence for the non-healthcare system was 36%. However, we cannot definitively conclude that the prevalence is lower in healthcare compared with non-healthcare settings. This is because a significant portion of the non-healthcare samples were associated with public places, such as those from wastewater treatment plants and agricultural sources, including animal feces, manure and compost, which influenced our results. In any case, environmental contamination in healthcare plays an important role in the dissemination of C. difficile infection between hospital staff and patients, leading to an increase in hospital-acquired cases.
Our results for the healthcare environment indicate that shoes, toilet or bathroom and wheelchairs have the highest contamination rates. Shoe soles of healthcare personnel and community-dwelling individuals can become colonized by microorganisms through direct or indirect transmission routes. Thus, shoe soles can be recognized as agents for the spread of C. difficile spores. Exposure of shoe soles to the ultraviolet-C (UVC) device significantly decreased the contamination rate of bacteria. It is recommended that UVC devices are utilized in healthcare environments to lower the number of colony-forming units of bacteria on shoe soles, which will consequently reduce the colonization of other surfaces.
The results showed that the non-healthcare environment has a remarkable contamination rate for C. difficile. The contamination rate on farms and in the public environment was slightly higher than in the home environment. This can be attributed to the fact that, in the home environment, surfaces are continually being disinfected. It is important to note that the overall contamination rate in home environments could be significantly lower than reported, because most of the home samples were taken from shoes, soil and toilets.
Among non-healthcare environments, farms have the highest prevalence. The bacterium has been isolated from various surfaces in farms, including soil, sand and mud. It was suggested that contaminated animals could be a reservoir of C. difficile for transmission to humans.58 The genetic similarity of C. difficile strains found in animals and humans reinforces the idea that animal farms can serve as reservoirs for human infections.60,61 On the other hand, studies have shown that animals, especially pigs, cattle and poultry, can shed the bacterium in their feces, contributing to its presence in the farm environment.58 It seems that the transmission chain between animals and the community has a role in the increase of community-acquired cases. This result highlights the importance of monitoring and controlling the presence of C. difficile in agricultural settings to mitigate the risk of infection in the human population.
In addition to farms, our results indicates the presence of the bacterium in various public places, such as wastewater treatment plants, where it was detected at various stages of the treatment process. This indicates that the bacterium can endure the treatment processes typically employed at these facilities, raising concerns about its potential release into the environment and subsequent risk to public health. The presence of C. difficile in wastewater suggests that these environments could serve as reservoirs for community-associated CDI. Hence, wastewater environments are critical in the transmission dynamics of C. difficile, necessitating enhanced monitoring and treatment strategies to mitigate the risks associated with this pathogen in public health contexts.
Overall, we report a notable global contamination rate for C. difficile among diverse environments over the last decade. Based on evidence, the risk of acquired environmental infection with C. difficile was similar to the risk of contact with an infected person.62 Therefore, environmental contamination with C. difficile plays an important role in increasing the number of reservoirs of C. difficile spores, leading to an increase in community-acquired cases. Therefore, there is a need to implement programs and guidelines on a global scale, taking account of the role of the environment in the spread of the disease.
The strengths of this study include its large total sample size and extraction of detailed data. However, this study has some limitations, and the results presented here should be interpreted with regard to these limitations. One primary limitation of this review is the possibility that our search strategy missed some studies. To address this limitation, we utilized PubMed and Google Scholar, both of which cover a wide range of scientific journals. Additionally, we conducted a thorough search of the references cited in eligible papers to identify any further relevant studies. Another limitation concerns the uneven distribution of studies across different strata, such as region. After stratifying the results by various variables, some strata had relatively few studies, which may have impacted the reliability of the prevalence estimates for those strata. We have transparently described the characteristics and number of studies per strata in the current article to ensure readers are aware of this limitation. Finally, it is important to highlight that the type of environmental sample is the key variable likely affecting prevalence comparisons across different strata. Nonetheless, we have tried to interpret the results with this factor in mind to offer a more nuanced understanding of the findings.
Conclusions
The findings of our study over the past decade reveal a significant prevalence of C. difficile contamination across various environments worldwide. This alarming trend underscores a pressing need to prioritize environmental factors and implement effective disinfection strategies as part of comprehensive prevention and control programs aimed at tackling this challenging disease. By addressing the environmental reservoirs of C. difficile, we can take proactive steps to mitigate the spread of this pathogen and improve public health outcomes.
Contributor Information
Mohammad Hasan Rabiee, Department of Epidemiology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975-148, Iran.
Lida Abdolmohammadi Khiav, Department of Anaerobic Bacterial Vaccine Production and Research, Clostridia Research Laboratory, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975-148, Iran.
Mohammad Hossein Fallah Mehrabadi, Department of Epidemiology, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj 31975-148, Iran.
Authors’ contributions
MHR and LAK contributed equally to this work. MHFM, MHR and LAK conceived and designed the study. LAK conducted the search and extracted data from paper. MHR and MHFM performed the statistical analysis and verified the underlying data. LAK and MHR wrote the first draft of the manuscript. All the authors reviewed and approved the final report. All the authors had full access to all the data in the study and had final responsibility for the decision to submit for publication. All the authors read and approved the final version of the manuscript.
Funding
The authors received no specific funding for this work.
Competing interests
No potential conflict of interest was reported by the authors.
Ethical approval
Not required.
Data availability
We are committed to sharing the data upon rational request.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
We are committed to sharing the data upon rational request.




