Nifuratel‐Nystatin combination for the treatment of mixed infections of bacterial vaginosis, vulvovaginal candidiasis, and trichomonal vaginitis

Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effectiveness and safety of nifuratel‐nystatin combination for the treatment of mixed infections of bacterial vaginosis, vulvovaginal candidiasis, and trichomonal vaginitis in women.

Background

Description of the condition

The vaginal protection system is based on the maintenance of an acidic pH of 3.5 to 4.5, where pathogenic organisms do not find the favourable conditions to proliferate, and acidophilic bacteria are in their ideal environment (Haya 2014). Vaginal discharge occuring under such conditions can be considered a normal and physiological occurrence; resulting from cervical secretion and other components derived from microorganisms that colonise the vaginal flora (Powell 2015). The breaking of the 'acidic pH‐acidophilic bacteria high metabolism‐lactic acid production‐acidic pH' virtuous cycle, usually associated with the presence of a genital tract infection, results in abnormal vaginal discharge (Mylonas 2011; Haya 2014; Venugopal 2017). Women with abnormal vaginal discharge most commonly have bacterial vaginosis (BV; 39.6%), vulvovaginal candidiasis (VVC; 11%), trichomonas vaginitis (TV; 0.8%), or any combination of these (Mulu 2015, Liang 2016). These infections cause vaginal discomfort and comprise over 95% of lower female genital tract infections (Haya 2014; Manish 2015). Approximately 20% to 30% of women with BV are also infected with Candida species. Coexistence of BV and TV pathogens is even more common, with infection rates of 60% to 80% (Sobel 2013). Apart from abnormal vaginal discharge, other signs and symptoms of these infections include itching, irritation, burning sensation, odour, and pain (Adeyba 2003; Hacer 2012; Karabulut 2010; Meena 2016; Olugbenga 2014; Yudin 2015).

BV, VVC, and TV have been associated with an increased risk of acquisition of human immunodeficency virus (HIV) and other sexually transmitted infections (STIs), due to decreased levels of protective lactobacilli and increased levels of local inflammation (Abbai 2016; Brotman 2010; Chinyere 2010; Gallo 2012; Lamichhane 2014;Thulkar 2010; Mulu 2015; Van Der Pol 2008; Rathod 2011; Schwebke 2016), The infections are also associated with adverse birth outcomes such as preterm birth, recurrent abortions, early miscarriages, and stillbirth (Brocklehurst 2013; Coleman 2013; Eshete 2013; Filho 2010; Saleh 2014; Sangkomkamhang 2015) as well as various gynaecological complications (Saleh 2014). Approximately 10 million gynaecological visits each year are attributed to vaginal discharge complaints (McClelland 2015). Throughout their lifetime, 75% of women are estimated to suffer from at least one episode of these infections (Fabio 2008). Thus, these infections are responsible for substantial psychological distress and economic costs (Divya 2003; Ehrström 2007; Olugbenga 2014). There is a high percentage of women for whom it is difficult to establish the etiological agent, or in whom the infection is diagnosed as mixed (Manish 2015). Several studies have shown that mixed vaginal infections with BV, VVC, and TV continue to occur at an increasing frequency (Manish 2015; Mashal 2017; Venugopal 2017). This provides strong impetus for treating the condition, particularly in sub‐Saharan Africa where the prevalence of the infections is high, amidst generalised HIV epidemics (Cohen 2012; Johnson 2012).

Diagnosis of mixed infections of BV, VVC, and TV by common methods is not precise, and use of pathogen‐specific methods is time consuming and often expensive (Ozyurt 2001). Diagnosis is based on identification of syndromes, which are combinations of symptoms and signs (Romoren 2007). The syndromic management of vaginal infections remains a public health priority (Khan 2014). The intervention relieves patients' symptoms and reduces transmission of etiological agents (Kamali 2003; WHO 2003). In addition, syndromic management is simple, rapid, problem‐oriented, cost‐effective, achieves high rate of cure and coverage of population, and can rely on non‐medical staff to manage cases (Bosu 1999). In resource‐poor settings which have limited laboratory facilities and lack trained personnel, syndromic management remains a rational approach to STI care. This syndromic approach is based on the assumption that genital tract infections share some common symptoms and signs, making it possible to assign them a specific etiology without the need for a laboratory test (Pepin 2006).

Bacterial vaginosis

BV is a clinical condition that occurs when there is an imbalance in normal vaginal micro‐organisms, with depletion of the dominant lactobacilli, increased vaginal pH, and overgrowth of anaerobic bacteria as a biofilm covering the vaginal epithelium (Machado 2016; Swidsinski 2005). Among genital infections, it is the leading disorder in women during their reproductive years, contributing to more than 60% of all vulvovaginal infections (Machado 2016; Sobel 2006). Being polymicrobial in nature, BV etiology remains unclear. The dense‐structure polymicrobial film is primarily constituted not only by Gardnerella vaginalis and Atopobium vaginae strongly adhered to the vaginal epithelium (Menard 2011; Polatti 2012; Swidsinski 2005), but also Mycoplasma hominis, Ureaplasma urealyticum and other anaerobes and facultative aerobic bacteria (Taylor 2013) such as Prevotella, Mobiluncus, Bacteroides, Clostriadiales and Peptostreptococcus (Mirmonsef 2012; Mylonas 2011). The biofilm displays a high resistance to the protective mechanisms of normal vaginal microflora (Patterson 2007), as well as increased tolerance to antibiotics (Swidsinski 2008). Therefore, vaginal biofilms play a key role not only in BV pathogenesis, but also in its treatment failure and recurrence. The overgrowth of the other bacteria is associated with biochemical changes including increased concentration of diamines, polyamines, organic acids, and enzymes such as mucinases, sialidases, and collagenases in vaginal fluid. These biochemical end products cause a further increase in pH and are responsible for the unpleasant fishy smell of the vaginal discharge in women with BV (Wolrath 2001).

BV is associated with sexual intercourse and occurs more commonly in sexually active women, however it is not regarded as an STI and the precise cause of this dysbacteriosis is not completely understood. Other risk factors include vaginal hygiene practices, use of an intrauterine contraceptive device, low socioeconomic status, new or multiple sexual partners, and smoking (Bradshaw 2014). Prevalence ranges from 4.9% to 35% in high‐income countries and from 20% to 51% in low‐ and middle‐income countries (Henn 2005; Lauent 2003). Available data indicate that the overall prevalence of BV is much higher among commercial sex workers and those who attend STI clinics (Bakare 2002; Behets 2001). BV is a mild disease and a substantial number of women are asymptomatic (Ghiasi 2014; Menard 2011), but it is sometimes accompanied by discharge, odour, pain, itching, or a burning sensation (Mashburn 2006). It has also been associated with serious health problems, including adverse perinatal and pregnancy outcomes such as high incidence of endometritis (Brocklehurst 2013), high incidence of pelvic inflammatory disease (PID) following abortion and gynaecologic procedures (Guerra 2006; Haggerty 2016; Rothman 2003), preterm labour, preterm delivery (Gözde 2016; Leitich 2003), acquisition of several STIs including HIV (Alcaide 2017; Alexander 2016; Gallo 2012; Kenyon 2013; Srinivasan 2012), and other pelvic complications (Achilles 2011; Brocklehurst 2013; Redelinghuys 2016).

In clinical practice, BV is diagnosed using the Amsel criteria. These include: a thin greyish homogenous discharge, pH of vaginal fluid being more than 4.5, release of a fishy odour on adding alkali, and clue cells (bacteria adherent to epithelial cells seen on microscopy). At least three of the four criteria have to be present for the diagnosis to be confirmed (Amsel 1983). An alternative diagnostic method which is more relevant for asymptomatic women is the use of a Gram‐stained vaginal smear with the Nugent or Spiegel score. The vaginal flora are examined and graded as normal (lactobacillus predominant), intermediate, or BV (lactobacillus‐deficient mixed flora) (Spiegel 1983; Nugent 1991). Antibiotic therapy is the mainstay of management of BV (see Table 1 for a list of recommended regimes from the United States Centers for Disease Control and Prevention (CDC 2010)). Most of these therapies have been associated with mild gastro‐intestinal side effects such as nausea, abdominal pain, constipation and vomiting. Other side effects include metallic taste, dizziness, fatigue, vulvar itching and, less commonly, hypersensitivity reactions (Abdali 2015; Menard 2011; Schwebke 2011). Up to 15% of patients fail to respond to initial antimicrobial therapy, and recurrence rates among responders remain significant, reaching up to 80% and necessitating repeated administration of antibiotics (Machado 2016; Menard 2011). Such repeated antibiotic exposure increases the risk of emergence of resistant strains, alteration of microbiota, and possible persistence of BV‐associated pathogens (Menard 2011). The high recurrence rate associated with these antibiotic therapies has stimulated the search for alternative treatment.

Table 1.

CDC‐recommended treatments for BV

Three recommended regimens Metronidazole 500 mg orally twice daily for 7 days Metronidazole gel 0.75%, 1 full application (5 g) intravaginally , once daily for 5 days Clindamycin cream 2%, 1 full application (5 g) intravaginally at bedtime for 7 days

Three alternative regimens Tinidazole 2 g orally once daily for 2 days Tinidazole 1 g orally once daily for five days Clindamycin 300 mg orally twice daily for 7 days Clindamycin ovules 100 mg intravaginally once at bedtime for 3 days

BV: bacterial vaginosis

CDC: Centers for Disease Control and Prevention

Vulvovaginal candidiasis

VVC is a yeast infection of the vagina, most often caused by Candida albicans (Cohen 2000; Dovnik 2015; El Ahmed 2012; Guzel 2011) or C. glabrata (Gonçalves 2016). Other yeasts that cause infection include C. tropicalis, C. parapsilosis, and C. krusei (Achkar 2010; Nurbhai 2007; Rezaei‐Matehkolaei 2016). Typically, a single species is identified, but two or more species have been found in some women with this infection (Amouri 2011; Cetin 2007; Fan 2008b; Mahmoudi 2011; Paulitsch 2006; Ritcher 2005). Most of the Candida mixed infections are caused by an association between C. albicans and C. glabrata (Amouri 2011; Mahmoudi 2011; Paulitsch 2006; Ritcher 2005). Accounting for between 40% and 50% of all cases, VVC is the most common form of infectious vaginitis and is responsible for substantial morbidity among reproductive‐age women; a significant burden to the healthcare system due to rising vaginitis‐related health care costs (Merrazzo 2002; Sobel 2006; Bradford 2013). Its development is usually attributed to the disturbance of the balance between Candida vaginal colonisation and host environment by physiological or non‐physiological changes (Gonçalves 2016). The condition occurs as a result of an imbalance in the normal vaginal microbiota and is characterised by a decrease or depletion of the lactobacilli species , and a concomitant overgrowth of Candida species. It is a common side effect of antibiotic treatment of BV (Pirotta 2003). Approximately 10% to 15% of asymptomatic women are colonised with Candida, and 75% of adult women will experience at least one episode with a high likelihood of recurrence (El Ahmed 2012; Fidel 1999). Approximately 40% to 50% of women suffer a second event (Paulitsch 2006), and 5% to 10% of all women will develop recurrent VVC (Prospero 2014; Sobel 2007). There has been an increase in infections during recent years, mainly due to antifungal resistance (El Ahmed 2012; Jatau 2006; McGregor 2006). Important risk factors for the development of VVC are the overuse of antibiotics, pregnancy, diabetes mellitus, immunosuppression, use of oral contraceptives, diaphragms, spermicide and intrauterine devices, and vaginal douching (Cohen 2000; Eckert 1998; El Ahmed 2012; Fidel 1999; Gonçalves 2016; Sobel 2006).

VVC is classified as uncomplicated or complicated depending on frequency, symptoms, microbiology and response to treatment Achkar 2010; Dovnik 2015). Uncomplicated cases are characterised by fewer than four sporadic episodes per year of mild to moderate infections caused by C. albicans in apparently healthy women (Sobel 2007). Complicated VVC includes episodes caused by other species of Candida, cases of severe infection, VVC during pregnancy, or vulvovaginal candidiasis associated with medical conditions such as immunosuppression or diabetes (Achkar 2010; Owen 2004; Eschenbach 2004). There have been reports of recurrent vulvovaginal candidiasis (RVVC), a form of complicated infection defined as four or more episodes of VVC per year (Achkar 2010; Peters 2014). Approximately 5% to 8% of VVC cases are recurrent, and C. glabrata and other non–C. albicans forms are isolated in 10% to 20% of these cases (Peters 2014). Although the infection is rarely life threatening, it is usually associated with discomfort, pain, sexual dysfunction, vulvar dryness, cracks, itching, burning and soreness (Ehrstrom 2006; Eschenbach 2004; Owen 2004; Paulitsch 2006). The clinical symptoms of VVC are nonspecific and can be associated with a variety of other vaginal diseases such as bacterial vaginosis and gonorrhoea (Anderson 2004; Mulu 2015). It is also associated with considerable direct and indirect economic costs (Foxman 2000), and enhanced susceptibility to HIV infection (Røttingen 2001). In addition, VVC may lead to complications such as PID, infertility, ectopic pregnancy, pelvic abscess, spontaneous abortion and menstrual disorders (Nwadioha 2010). Diagnosis of VVC is based on a combination of clinical signs and symptoms, microscopic examination, or vaginal culture (Sobel 2004). See Table 2 and Table 3 for a list of recommended treatments for VVC. Recurrence of VVC is commonly reported (Peters 2014), and inappropriate use of antifungal drugs and introduction of 'over the counter' antimycotics predispose people to development of antifungal resistance (Salehei 2012).

Table 2.

CDC‐recommended treatments for Uncomplicatied VVC

Over‐the‐Counter Intravaginal Agents

Prescription Intravaginal Agents

Butoconazole 2% cream 5 g intravaginally for 3 days OR Clotrimazole 1% cream 5 g intravaginally for 7 to 14 days OR Clotrimazole 2% cream 5 g intravaginally for 3 days OR Miconazole 2% cream 5 g intravaginally for 7 days OR Miconazole 4% cream 5 g intravaginally for 3 days OR Miconazole 100 mg vaginal suppository, one suppository for 7 days OR Miconazole 200 mg vaginal suppository, one suppository for 3 days OR Miconazole 1,200 mg vaginal suppository, one suppository for 1 day OR Tioconazole 6.5% ointment 5 g intravaginally in a single application

Butaconazole 2% cream (single dose intravaginally for 1 day OR Nystatin 100,000‐unit vaginal tablet, one tablet for 14 days OR Terconazole 0.4% cream 5 g intravaginally for 7 days OR Terconazole 0.8% cream 5 g intravaginally for 3 days OR Terconazole 80mg vaginal suppository

CDC: Centers for Disease Control and Prevention

VCC: vulvovaginal candidiasis

Table 3.

CDC‐recommended treatments for Complicated VVC

RVVC
Initial regimens: 7 to 14 days of any topical azole drug OR Fluconazole 100, 150, or 200 mg orally once daily every third day for a total of 3 doses (day 1, 4, and 7)	Maintenance regimen: Fluconazole 100, 150, or 200 mg orally once weekly for 6 months
Severe VVC
Intravaginally once daily for 7 to 14 days of any topical azole drug OR Fluconazole 150 mg orally once daily in two doses (second dose 72 hours after initial dose)
Nonalbicans VVC
Nonfluconazole azole (oral or topical) Seven to 14 days OR Boric acid gelatin capsule Intravaginally once daily for 14 days
Abnormal host
More prolonged (i.e. 7 to 14 days) conventional antifungal drugs is necessary
Notes: • CDC = Centers for Disease Control and Prevention • Information from references CDC 2010

RVVC: recurrent vulvovaginal candidiasis

VCC: vulvovaginal candidiasis

Trichomonal vaginitis

TV is the causative agent of trichomoniasis, the most common nonviral STI (Prospero 2014; Glehn 2017). It affects 276.4 million people each year, the majority of whom live in low‐ and middle‐income countries (WHO 2011). Global prevalence of TV has been estimated at 8.1% for women and 1.0% for men (WHO 2001), but this varies greatly among different populations (Ton 2015). The majority of infected women (85%) are asymptomatic (Meltes 2015). In symptomatic women, the infection is characterised by vaginal discharge with frothy, foul‐smelling grey or green‐yellow fluid, intense itching, oedema, redness of the cervix, vulvovaginal soreness or irritation, itching, dyspareunia (painful sexual intercourse), postcoital bleeding, pelvic pain, and urinary symptoms (Hacer 2012; Prospero 2014).

The incidence of vaginal trichomoniasis is high among women with new and multiple sexual partners and other at‐risk sexual behaviours. Poverty, low socio‐economical status, and low educational level have also been associated with high risk of infection (Arabi 2014). Infected pregnant women may be at risk of adverse birth outcomes such as postabortion infection, premature labour, preterm labour, preterm delivery and having infants with a low birth weight (Chinyere 2010; Coleman 2013). Trichomoniasis is also associated with infertility, enhanced predisposition to neoplastic transformation in cervical tissues, and increased risk of transmission of STIs including HIV (Mercer 2016; Salawu 2016; Saleh 2014). Although rare, TV infection can be transmitted perinatally (Schwandt 2008), and can cause vaginal and respiratory infections in neonates (Carter 2008; Temesvari 2002).

Clinical diagnosis of TV is not specific and laboratory confirmation is necessary. Wet mount microscopy that shows motile trichomonads (Krieger 1988), and culture techniques (Stary 2002), are widely used for diagnosis. Wet mount microscopy is a cheap and quick diagnostic method, but its sensitivity is low as some women who have a negative wet mount will still have trichomoniasis (Swygard 2004). In symptomatic women who are suspected to have trichomoniasis but no observable motile trichomonads, culture is recommended (Owen 2004). Enzyme immunoassay, nucleic acid amplification, and immunofluorescence methods are also available (Andrea 2011; Huppert 2007; Sobel 2005). See Table 4 for a list of regimens for treating TV, as recommended by the United States Centers for Disease Control and Prevention (CDC 2010). Despite the widespread use of these antitrichomonal agents, resistance has been relatively rare and generally managed by higher doses (Forna 2003; Kissinger 2015). Common adverse reactions reported include urticaria (hives), facial edema, flushing, and fever. Recurrence of infection is thought to be mainly caused by reinfection from a partner or failure to complete the treatment course.

Table 4.

4 CDC‐recommended treatments for TV

Recommended regimens Metronidazole 2 g orally in a single dose OR Tinidazole 2 g orally in a single dose

Alternative regimen Metrolnidazole 500 mg orally twice a day for 7 days

CDC: Centers for Disease Control and Prevention

TV: trichomonal vaginitis

Description of the intervention

Treatment of vaginal disorder due to mixed infection of BV, VVC, and TV can be challenging due to frequent recurrences (Paulitsch 2006; Sobel 2006b). Hence, timely diagnosis and appropriate intervention is essential. Nifuratel, a nitrofuran‐derivative, is a synthetic chemotherapeutic agent for the treatment of infectious diseases of the urinary and genital tracts. It is an antiprotozoal, antifungal, and antibacterial agent which is safe, well tolerated, and has no known teratogenic effect (Mendling 2002). It can thus be used in the treatment of many infections of the genito‐urinary tract (Mendling 2002). Nifuratel has been shown to have strong activity against T. vaginalis and has a broad spectrum of antibacterial action (Liang 2016; Togni 2011). It has been used mainly in the treatment of vulvovaginal infections and has also been recommended for the treatment of urinary tract infections. It is readily absorbed from the gastrointestinal tract and partially metabolised mainly in the liver. It is not effective in bacterial systemic infections and has no effect on bacteria in blood or tissues outside the genito‐urinary tract. Adverse effects associated with nifuratel are rare and include gastrointestinal disturbance, peripheral neuropathy and thrombocytopenic pupura. Allergic reactions, haemotoxicity, blood dyscrasias and pulmonary reactions may also occur (Liang 2016; Polatti 2003).

Like many other antifungals and antibiotics, nystatin is of bacterial origin. It is a membrane‐active polyene antifungal antibiotic biosynthesised by a bacterial strain, Streptomyces noursei (Fjaervik 2005; Wong 2014). It is particularly effective against yeast microorganisms of the genus Candida, including albicans and non‐albicans strains (Salehei 2012; Mahmoudabadi 2013). It is used to treat various Candida infections including thrush, oesophageal candidiasis, and vaginal yeast infection. Absorption from the intestinal track is poor, detectable blood concentrations are not obtained after usual doses, it is safe for oral use, and does not have problems of drug interactions. Occasionally, serum levels of the drug can be identified from oral, vaginal, or cutaneous administration, and this can lead to systemic toxicity (Semis 2013). Following oral administration, nystatin is excreted almost entirely in faeces as unchanged. (Sklenár 2013). Nystatin is generally well tolerated, with few adverse events reported (Dressen 2012). However, high oral doses may cause nausea, vomiting or diarrhoea; hypersensitivity reactions have also been reported, though rarely (Lyu 2016).

Nifuratel‐nystatin combination is a wide spectrum antimicrobial agent used for treatment of mixed vaginal infections caused by at least two of the triad pathogens (fungi, bacteria, and T. vaginalis) (Cepický 2003). It may be safely given orally, intravaginally, or applied topically due to its minimal absorption through the mucocutaneous membrane (Cepický 2003). Studies have established good clinical and microbiological influence in more than 80% of the treated patients (Karag'ozov 1999; Zlatkov 1988). The trial results have confirmed a linear relationship between dose and effect, the least effective dose being nifuratel 250 mg plus nystatin 100,000 IU, and the best dose in terms of risk/benefit being nifuratel 500 mg plus nystatin 200,000 IU once daily for five days (Neut 2015; Polatti 2003). It is therefore necessary to conduct a rigorous systematic review of the available clinical trials, to help determine the effectiveness and safety of this combination for the treatment of mixed vaginal infections, and to identify strategic areas for future research.

How the intervention might work

The nifuratel‐nystatin combination has intense and efficacious trichomonacidal, bactericidal, and mycostatic action; making it effective in the treatment of vaginal infections of mixed aetiology. Nifuratel is a nitrofuran derivative with strong anti‐protozoan and antibacterial activity as well as certain fungicidal effects, but it is not active against physiological flora (Polatti 2012). It has a broad antibacterial spectrum of action, including both Gram‐negative and Gram‐positive organisms (Mendling 2002). It is usually bacteriostatic but may be bactericidal in action, depending on the concentration of the drug attained at the site of the infection and the susceptibility of the infecting organism. Although the exact mechanism of action has not been fully elucidated, it appears to inhibit several microbial enzyme systems, including acetyl coenzyme A interference with the early stages of the glucose metabolism of the microorganism (AHFS 1991).

Nystatin is both fungistatic (inhibits the growth of fungi) and extremely fungicidal (kills the fungal cells). Nystatin inhibits fungal cell membrane synthesis by binding to the sterol “ergesterol”, a major component of the fungal membrane. It creates pores in the membrane, leading to depolarisation, subsequent leakage of vital cytoplasmic components, and acidification, thus stopping enzymatic action and causing death of the fungus (Chulkov 2015; Semis 2013). Other mechanisms of action include oxidative damage of the fungal cells.

The above characteristics led to the combination of nifuratel with nystatin in a single compound; maintaining the antibacterial and antiprotozoan activity of nifuratel and enhancing the antimycotic activity of nystatin (Polatti 2003). Despite its broad‐spectrum antimicrobial property, this drug combination is not effective against lactobacilli (Polatti 2012), which is a clear advantage in the treatment of vaginal infections. The combination would ensure a wide range of antimicrobial actions with rapid and noteworthy symptomatic relief in patients with mixed vaginal infections of bacterial, fungal, and protozoan origin.

Why it is important to do this review

Vaginal infection is the most common reason for non‐routine gynaecological visits and results in high levels of anxiety and decreased quality of life. Although effective treatments are available for individual infections of trichomonal vaginitis, vulvovaginal candidiasis, and bacterial vaginosis (CDC 2010; Nurbhai 2007; Oduyebo 2009), mixed vaginal infections occur frequently (McClelland 2015). These should be treated effectively to reduce suffering and devastating consequences in women. Concerns regarding mixed infections have led to the development of broad spectrum antimicrobials including the nifuratel‐nystatin combination to improve the treatment of mixed vaginal infections. Some evaluations have shown that it is effective and its exceptionally broad antibacterial, antifungal and trichomonicidal activity makes it a drug of choice in cases where mixed vaginal infection due to BV, VVC and TV is suspected (Cepický 2005; Polatti 2003). It is therefore necessary to conduct a rigorous systematic review of the available clinical trials, addressing the certainty of the current knowledge and making it possible to assess the effectiveness and safety of this intervention.

Objectives

To assess the effectiveness and safety of nifuratel‐nystatin combination for the treatment of mixed infections of bacterial vaginosis, vulvovaginal candidiasis, and trichomonal vaginitis in women.

Methods

Criteria for considering studies for this review

Types of studies

We will include only randomised controlled trials (RCTs), defined as studies in which the investigators allocated participants (or clusters of participants) at random to treatment groups. Random allocation guarantees that participants in comparison arms would differ only in their exposure (or non‐exposure) to the treatment assessed. Regarding cluster‐randomised trials, we will include only trials with at least two intervention sites and two comparison sites. We will exclude quasi‐randomised trials, which are trials where participants were allocated to treatment groups using methods that are not random. We will also exclude cross‐over trials because of the carry‐over effect (Higgins 2011).

Types of participants

Women in any setting, of any age or race, with vaginal discharge (syndromic diagnosis).

Types of interventions

The eligible intervention is nifuratel‐nystatin combination treatment irrespective of formulation, concentration, frequency, duration, and route of administration. Eligible comparison interventions will be:

• conventional drugs (including tinidazole 2 g orally + fluconazole 150 mg orally, or tinidazole 2 g orally + clortrimazole intravenous therapy (IV), or fluconazole 150 mg orally + clindamycin IV 2% 5 g each day for seven days);

• probiotics;

• vaginal douching;

• acidifying agents (including boric acid, cider, vinegar, and vaginal gels).

Types of outcome measures

Primary outcomes

• Clinical cure (i.e. disappearance of symptoms and signs), measured during the first seven days, between 7 and 14 days, or 14 days after treatment.

• Microbiological cure (i.e. no evidence of trichomonal, fungal, or bacterial infection on microscopy examination or vaginal culture), split into short‐term microbiological cure (i.e. within 5 to 15 days of starting treatment) and long‐term microbiological cure (i.e. 2 to 12 weeks after treatment).

• Adverse events, i.e. any untoward medical occurrences in a patient or clinical investigation subject administered a pharmaceutical product, which do not necessarily have a causal relationship with this treatment, as described by the International Conference on Harmonisation (ICH) Harmonised Tripartite Guideline (ICH 1996).

• Adherence

Secondary outcomes

• Time to recovery, defined as the time to achieve clinical or microbiological cure.

• Relapse, i.e. symptom recurrence confirmed by microscopic examination or vaginal culture at 1 and 3 months after microbiological cure.

• Participant’s satisfaction with treatment.

• Cost‐effectiveness

Search methods for identification of studies

We will attempt to identify as many relevant RCTs as possible through a comprehensive search, irrespective of their language and publication status (published, unpublished, in press, and in progress). We will perform both electronic searches of bibliographic databases and handsearching, as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

Electronic searches

We have contacted the Information Specialist of the Cochrane Sexually Transmitted Infections (STI) Group in order to devise a comprehensive search strategy to capture as many relevant studies as possible in electronic databases. For this purpose, we will use a combination of exploded controlled vocabulary (MeSH, Emtree, DeCS) and free‐text terms (considering spelling variants, plurals, synonyms, acronyms and abbreviations) for the target condition (bacterial vaginosis, vulvovaginal candidiasis and trichomonal vaginitis) and the intervention (nifuratel‐nystatin), with field labels, wildcards, proximity operators and boolean operators. The search strategies and their results can be found in Appendix 1.

We will search the following electronic databases.

• MEDLINE, Ovid platform: inception to present.

• MEDLINE In‐Process & Other Non‐Indexed Citations, Ovid platform: inception to present.

• MEDLINE Daily Update, Ovid platform: inception to present.

• Embase.com: inception to present.

• Cochrane Central Register of Controlled Trials, Ovid platform: inception to present.

• LILACS, iAHx interface: inception to present.

For MEDLINE and EMBASE, we will used the Cochrane standardised search strategies for identifying RCTs. We will combine the LILACS search strategy with the IAHx interface RCT filter.

Searching other resources

We will attempted to identify additional relevant studies by:

• searching the Cochrane STI Review Group’s Specialized Register, which includes randomised controlled trials (RCTs), non‐randomised controlled trials, controlled before‐and‐after studies, and interrupted‐time‐series studies, from 1944 to present;

• searching trial registries:

• • the WHO International Clinical Trials Registry Platform (ICTRP) portal (apps.who.int/trialsearch/): inception to 12 March 2018;

  • ClinicalTrials.gov (clinicaltrials.gov): inception to 12 March 2018

  • the Web of Science®: inception to 12 March 2018.

Grey literature

We will search for grey literature in the System for Information on Grey Literature in Europe “OpenGrey” (www.opengrey.eu/) from inception to 12 March 2018.

Handsearching

We will handsearch the conference proceeding abstracts of the following events:

• the International Society for Sexually Transmitted Diseases Research (ISSTDR) (www.isstdr.org/): 2007, 2009, 2011, 2013, 2015 and 2017;

• the International Congress on Infectious Diseases (ICID) (www.isid.org/): 2010, 2012, 2014, 2016 and 2018;

• the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) (www.icaac.org/): 2011, 2012, 2013, 2014, and 2015;

• the International Federation of Gynecology and Obstetrics (FIGO) (www.figo2012.org/home/): 2009, 2012, and 2015.

Also, we will handsearch within previous systematic reviews and other relevant publications on the same topic. Finally, we will search the citation lists from reviewed articles.

Data collection and analysis

Selection of studies

Two review authors, Jael Obiero (JO), Stephen Rulisa (SR), will independently screen all abstracts identified by the search strategy, for potentially eligible studies. For each potentially eligible study, the two authors (JO and SR) will independently assess the eligibility of the full‐text article using prespecified trial inclusion criteria. The authors will compare their results and resolve any disagreements by discussion and consensus, with arbitration by a third author (Paul Ogongo (PO)).

Should we judge (after duplicate screening of the abstract) that a study published in a language other than English is suitable for inclusion in the review, we will obtain a translation into English. We will also seek additional information from trial authors where published reports do not allow for an accurate assessment of study eligibility.

Data extraction and management

We will design and pilot test a form to extract data. Two authors (JO and SR or JO and PO) will independently extract data from eligible studies, using the piloted form. The authors will compare their results and resolve any disagreement through discussion and consensus, with arbitration by the fourth author (Charles S Wiysonge (CSW).

For each included study, the two authors will independently extract and record the following data.

• Trial setting and design

• Power calculation (whether performed or not)

• Inclusion and exclusion criteria

• Primary and secondary outcomes, and how they were defined and measured

• Baseline characteristics of the participants: age, marital status, contraceptive habits, sexual intercourse during treatment, history of sexually transmitted infections (STIs), sexual behavioural history

• Total number of intervention groups

• Types of interventions: nifuratel‐nystatin type (any concentration, frequency, duration and route)

• Types of comparison: placebo, no treatment, conventional drugs, probiotics, vaginal douching, and acidifying agents (of any concentration, frequency, duration and route)

• Number of participants enrolled, randomised, excluded after randomisation, and analysed

• Number of participants lost to follow‐up in each group

• Length of participants' follow‐up for specific outcomes

• Outcomes reported in results

• How adverse event reports were validated

• Funding sources

• Ethical issues: ethics approval, informed consent

When information regarding any of the above is unclear, we will attempt to contact authors of the original trial reports to ask for further details. For any randomised trial reported in one publication, we will extract data directly onto the data collection form for that study. In case of multiple publications of a single study, we will extract data from each report separately and then reconcile the information across data collection forms.

One author (JO) will enter extracted data into RevMan and a second author (SR or PO) will check them for accuracy.

Assessment of risk of bias in included studies

Two review authors (JO, PO) will assess the risk of bias independently for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will resolve any disagreements by discussion or by involving another author (GM). We will assess the risk of bias according to the following domains:

• random sequence generation;

• allocation concealment;

• blinding of participants and personnel;

• blinding of outcome assessment;

• incomplete outcome data;

• selective outcome reporting;

• other bias.

We will judge each potential source of bias as high, low or unclear and provide a quote from the study report together with a justification for our judgement in the 'Risk of bias' table. We will summarise the 'Risk of bias' judgements across different studies for each of the domains listed. We will consider blinding separately for different key outcomes where necessary. Where information on risk of bias relates to unpublished data or correspondence with a trialist, we will note this in the 'Risk of bias' table.

When considering treatment effects, we will take into account the risk of bias for the studies that contribute to that outcome.

Assessment of bias in conducting the systematic review

We will conduct the review according to this published protocol and justify any deviations from it in the 'Differences between protocol and review' section of the systematic review.

Measures of treatment effect

Dichotomous data

For dichotomous data, we will calculate risk ratios (RRs) with 95% confidence intervals (CIs). We have chosen to use the RR because it has consistency, works well with low or high rates of events, and it is easy to interpret and use in clinical practice.

Continuous data

For continuous data, we will calculate the unadjusted mean difference (MD) between treatment groups if all studies used the same measurement scale. In instances where measures are on different scales but the scales are clinically homogeneous, we will calculate the standardised mean difference (SMD). In each scenario, we will calculate the 95% CI.

Time‐to‐event data

For time‐to‐recovery data, we will calculate the hazard ratio (HR) and its 95% CI.

Unit of analysis issues

It is most likely that the unit of randomisation in included studies will be the individual patient. In addition, we expect that eligible studies will collect and analyse a single measurement for each outcome from each participant. However, in the unlikely event that we find eligible studies that did not use a parallel group design, we will proceed as described in section 9.3 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011).

Dealing with missing data

We will contact authors of eligible studies to obtain any missing data. Should we fail to obtain the requested data, we will report the percentage of observations with missing data and use sensitivity analyses to assess the effect of missing data on our findings. We plan to analyse study participants in groups to which they were randomly allocated, regardless of which or how much treatment they received. In our analyses, the numerator for each outcome in each study group will be the number of participants randomly allocated to that group for whom outcome data are available. The denominator for each outcome in each study group will be the number of participants randomly allocated to that group at the start of the trial, irrespective of how many randomised participants have missing data for that outcome.

Assessment of heterogeneity

We will assess clinical heterogeneity among the trials by considering the variability in trial participants, interventions, and outcomes. We will pool data from clinically homogeneous trials and assess statistical heterogeneity by visually inspecting the forest plots to check for overlapping confidence intervals. In addition, we will assess statistical heterogeneity using the Chi² test of homogeneity, defining statistical significance at P = 0.10. If there is no significant statistical heterogeneity, we will conduct fixed‐effect meta‐analysis. In the presence of significant statistical heterogeneity, we will conduct random‐effects meta‐analysis and investigate the source of the heterogeneity using subgroup analyses. We will also use the I² statistic to describe the proportion of observed variation of effects across trials that reflect variation in true effect sizes rather than sampling error. In addition, for all random‐effects meta‐analyses, we will measure the among‐study variance using Tau². We will regard heterogeneity as substantial if Tau² is greater than zero (Higgins 2011).

Assessment of reporting biases

For any meta‐analysis that includes 10 or more trials, we will investigate publication bias using funnel plot asymmetry tests. When there are fewer than 10 trials in a meta‐analysis, the power of funnel plots to distinguish chance from real asymmetry is too low. We will first assess funnel plot asymmetry visually, followed by formal tests (Higgins 2011). For continuous outcomes, we will use the test proposed by Egger and colleagues to test for asymmetry (Egger 1997). For dichotomous outcomes, we will use the test proposed by Harbord and co‐workers (Harbord 2006).

Data synthesis

We will carry out statistical analysis using Review Manager (Review Manager 2014). We will use fixed‐effect meta‐analysis for combining data where it is reasonable to assume that studies are estimating the same underlying treatment effect, i.e. where trials are examining the same intervention, and trial participants and methods are judged to be reasonably identical.

Should substantial statistical heterogeneity be detected, we will use random‐effects meta‐analysis to produce an overall summary if an average treatment effect across trials is considered clinically meaningful. The random‐effects summary will be treated as the average range of possible treatment effects and we will discuss the clinical implications of treatment effects differing between trials.

If there is substantial clinical diversity or the average treatment effect is not clinically meaningful, we will not combine trials in a meta‐analysis.

'Summary of findings' table

We will use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the certainty (or "quality") of the evidence and produce a 'Summary of Findings' table (Guyatt 2008; Higgins 2011). We will include the following outcomes.

• Clinical cure at 14 days from start of treatment;

• Microbiological cure at 2 weeks from start of treatment;

• Adverse events; and

• Adherence.

We will downgrade the quality of evidence in the presence of the following factors:

• study limitations;

• unexplained inconsistency of results;

• indirectness of evidence;

• imprecision; and

• publication bias.

Subgroup analysis and investigation of heterogeneity

If we detect significant statistical heterogeneity, our first step will be to re‐check that the data were correctly extracted and correctly entered in Review Manager. If significant statistical heterogeneity is present and is not caused by data errors, we will explore the potential reasons using subgroup analysis.

We have predefined subgroups as follows:

• pregnant versus non‐pregnant women;

• immunocompetent versus immunocompromised (e.g. due to HIV or diabetes mellitus);

• short‐term (i.e. 1 to 7 days) versus long‐term (i.e. more than 7days) treatment;

• route of administration (oral versus local);

• different doses of nifuratel‐nystatin (i.e. least, middle and high); and

• recurrent infection.

We will restrict subgroup analyses to the primary outcomes.

Sensitivity analysis

We plan to perform sensitivity analyses for aspects of the review that could potentially affect the results. Such aspects may include unit of analysis errors, high risk of bias, and funnel plot asymmetry.

We will define high risk of bias based on three criteria, namely, inadequate allocation concealment, inadequate blinding of outcome assessors, and differential loss to follow‐up. If we have evidence to suggest that small study effects are influencing the results of a meta‐analysis, we will conduct sensitivity analyses to assess the robustness of the meta‐analysis conclusions to different assumptions about the causes of funnel plot asymmetry.

We also plan to carry out sensitivity analyses to explore the effects of meta‐analysis method (fixed‐effect versus random‐effects) for outcomes with substantial heterogeneity.

Appendices

Appendix 1. Search strategies

MEDLINE / CENTRAL (Ovid)

1. exp Vaginosis, Bacterial/

2. (bacterial adj5 vagin$).tw.

3. (vagina$ adj5 infection).tw.

4. (vagina adj5 inflammation).tw.

5. ?olpitis.tw.

6. exp Candidiasis, Vulvovaginal/

7. (vulvovaginal adj5 candidias$).tw.

8. (vulvovaginal adj5 Monilias$).tw.

9. (vaginal adj5 yeast adj5 infection$).tw.

10. (genital adj5 candidias$).tw.

11. (vaginiti$ adj5 monilial).tw.

12. (vagin$ adj5 candid$).tw.

13. exp Trichomonas Vaginitis/

14. (trichomon$ adj5 vagin$).tw.

15. (trichomonias$ adj5 human).tw.

16. or/1‐15

17. exp Nifuratel/

18. nifurantel.tw.

19. 17 or 18

20. exp Nystatin/

21. nystatin$.tw.

22. 20 or 21

23. 19 and 22

24. randomized controlled trial.pt.

25. controlled clinical trial.pt.

26. randomized.ab.

27. placebo.ab.

28. clinical trials as topic.sh.

29. randomly.ab.

30. trial.ti.

31. or/24‐30

32. exp animals/ not humans.sh.

33. 31 not 32

34. 16 and 23 and 33

EMBASE (embase.com)

1. 'vaginitis'/exp

2. (bacterial NEAR/5 vagin*):ab,ti

3. (vagina* NEAR/5 infection):ab,ti

4. (vagina NEAR/5 inflammation):ab,ti

5. ?olpitis:ab,ti

6. 'vagina candidiasis'/exp

7. (vulvovaginal NEAR/5 candidias*):ab,ti

8. (vulvovaginal NEAR/5 Monilias*):ab,ti

9. (vaginal NEAR/5 yeast NEAR/5 infection*):ab,ti

10. (genital NEAR/5 candidias*):ab,ti

11. (vaginiti* NEAR/5 monilial):ab,ti

12. (vagin* NEAR/5 candid*):ab,ti

13. 'vaginal trichomoniasis'/exp

14. (trichomon* NEAR/5 vagin*):ab,ti

15. (trichomonias* NEAR/5 human):ab,ti

16. #1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13 OR #14 OR #15 OR #16

17. 'nifuratel'/exp

18. nifurantel:ab,ti

19. #17 OR #18

20. 'nystatin'/exp

21. nystatin*:ab,ti

22. #20 OR #21

23. #19 AND #22

24. "randomized controlled trial"/de

25. "controlled clinical study"/de

26. random*:ti,ab

27. randomization/de

28. "intermethod comparison"/de

29. placebo:ti,ab

30. (compare OR compared OR comparison):ti

31. ((evaluated OR evaluate OR evaluating OR assessed OR assess) AND (compare OR compared OR comparing OR comparison)):ab

32. (open NEAR/1 label):ti,ab

33. ((double OR single OR doubly OR singly) NEAR/1 (blind OR blinded OR blindly)):ti,ab

34. "double blind procedure"/de

35. (parallel NEXT/1 group*):ti,ab

36. (crossover OR "cross over"):ti,ab

37. ((assign* OR match OR matched OR allocation) NEAR/5 (alternate OR group* OR intervention* OR patient* OR subject* OR participant*)):ti,ab

38. (assigned or allocated):ti,ab

39. (controlled NEAR/7 (study OR design OR trial)):ti,ab

40. (volunteer OR volunteers):ti,ab

41. trial:ti

42. "human experiment"/de

43. #24 OR #25 OR #26 OR #27 OR #28 OR #29 OR #30 OR #31 OR #32 OR #33 OR #34 OR #35 OR #36 OR #37 OR #38 OR #39 OR #40 OR #41 OR #42

44. #16 AND #23 AND #43 AND [embase]/lim

Contributions of authors

Jael Obiero and Stephen Rulisa wrote the first draft of the protocol and all authors contributed important intellectual input into the manuscript.

Sources of support

Internal sources

• No sources of support supplied

External sources

• The Aubrey Sheiham Leadership Award for Evidence‐Based Healthcare in Africa, South Africa.

Declarations of interest

None known

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