Mycoplasma genitalium is a sexually transmitted infection (STI) increasingly reported in both high- and low-risk populations worldwide. Compared with other STI, there are little data on the prevalence of M. genitalium.1 In our recent cross-sectional study among female sex workers in Uganda, we estimated the prevalence of M. genitalium at 14% (95% confidence interval [CI]: 12%–17%).2 The infection was more prevalent in younger age groups, in HIV-positive women, and in those coinfected with Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV).
A systematic review of epidemiologic studies found that M. genitalium infection is associated with HIV infection, especially in sub-Saharan Africa.3 This is calling for an urgent consensus on whether and how best to control and treat this novel STI, particularly in areas with a substantial burden of HIV infection. Unfortunately, more than 2 decades after it was first isolated, little is certain about the pathogenicity of M. genitalium, especially in women. Although the bacterium is now recognized as an important cause of nongonococcal nonchlamydial urethritis in men, the role of M. genitalium in upper and lower genitourinary tract diseases in women remains inconclusive.4 Also the choice of antibiotics to treat M. genitalium infection is not established. Tetracycline and the older quinolone derivatives fail to eliminate the infection, and treatment with azithromycin seemed more promising until it transpired that the bacterium may have developed resistance to this antibiotic.5 Satisfactory treatment outcomes were obtained with moxifloxacin, but this drug is not affordable in most low-income countries.6,7
In most settings in Africa, STI diagnosis is based exclusively on symptoms and signs. So far, few studies from sub-Saharan Africa have presented data on M. genitalium infection.8–10 The aim of our study was to describe symptoms and signs associated with this infection among high-risk women in Uganda and to investigate whether the clinical pattern varied by HIV status. Such data are urgently needed to understand the pathogenicity of the bacterium and to decide whether to include M. genitalium treatment into established STI syndromic guidelines.
Study Population and Clinical Procedures
Between April 2008 and May 2009, 1027 women who engaged in sex work and/or were employed in entertainment facilities, were recruited from red-light areas in southern Kampala.
The recruitment process has been described in detail previously.11 Consenting participants were interviewed about their sociodemographic characteristics, risk behavior, and presence of current symptoms of STI, if any. An experienced clinician or midwife performed a gynecological examination including the use of a speculum. All reported symptoms and observed signs were recorded on standardized data entry forms.
Full study procedures have been described previously.2,11 Briefly, 2 endocervical specimens were collected, one for the diagnosis of gonococcal and chlamydial infection and another to be stored for a later diagnosis of M. genitalium. One swab was collected from the posterior fornix of the vagina to be inoculated for culture of TV, another from the lateral vaginal walls to prepare a slide for the detection of bacterial vaginosis (BV) and of Candida infection. Blood was collected for HIV, herpes simplex virus type 2 (HSV2), and syphilis testing. Women with symptomatic STIs were treated syndromically, whereas women with asymptomatic STIs were treated when laboratory results became available. As the diagnosis of M. genitalium was made on stored specimens up to 2 years after specimen collection, women were not specifically treated for M. genitalium.
Cervicitis was defined as presence of mucopurulent endocervical discharge on clinical examination; a vaginal infection was defined as presence of profuse and/or mucopurulent or white vaginal discharge. Women presenting with vaginal infection and/or cervicitis were diagnosed as having vaginal discharge syndrome. NG and CT were considered as pathogens responsible for cervicitis; TV, Candida albicans, and BV as possible causes of vaginal infections. Pelvic inflammatory disease (PID) was defined as reported lower abdominal pain and/or dyspareunia confirmed by bimanual palpation.
For the detection of M. genitalium, the endocervical specimen was inserted in a buffer solution, using Cobas Amplicor STM collection tubes (Roche Diagnostic Systems Inc., Branchburg, NJ). The samples were stored at 4°C at the clinic until transport to the MRC/UVRI Laboratories in Entebbe, within 12 hours of collection. The specimens were kept at −20°C until sample collection from all enrolled women was completed and then finally sent on dry ice to the Centre for HIV and Sexually Transmitted Infections, National Institute for Communicable Diseases, National Health Laboratory Service in Johannesburg for polymerase chain reaction (PCR) testing. Genomic DNA was extracted from endocervical specimens using an X-tractor Gene automated DNA extractor (Corbett Life Science, Concorde, Australia) and tested for M. genitalium using a commercially available Real-TM assay (Sacace Biotechnologies, Como, Italy) targeting the DNA gyrase subunit B of M. genitalium. Further details of the PCR test have been reported previously.2
Laboratory testing for all other infections was performed at the central laboratories of the MRC/UVRI Uganda Unit in Entebbe. NG and Chlamydia trachomatis were diagnosed on endocervical specimens using the Amplicor PCR test (Roche Diagnostic Systems Inc.) and TV was detected using the commercial culture kit (InPouch TV, BioMed Diagnostics, White City, OR). Microscopy on a gram-stained vaginal specimen was performed to diagnose BV (using the Nugent's criteria) and Candida infection. Serum samples were tested for antibodies against HIV-1 (Abbott Determine HIV-1/2 with confirmation by 2 independent ELISA tests Vironostika Uniform II plus O, Murex HIV 1.2.O), for HSV2 (IgG ELISA test, Kalon Biologicals Ltd, Surrey, United Kingdom) and to diagnose syphilis infection (RPR Biotec and TPHA Biotec). Active serological syphilis was defined by a positive RPR test confirmed by a positive TPHA result.
Data were double entered in Access and analyzed using STATA 11.0 (Stata Inc., College Station, TX). Associations of clinical signs and symptoms with M. genitalium infection and coinfections were first assessed using a χ2 statistic. Then, each symptom and sign was considered in turn as the outcome (independent variable) and M. genitalium as the exposure (dependent variable). Age as well as other coinfections (HIV, HSV2, active syphilis, NG, CT, TV, C. albicans, and BV) were considered as potential confounders. All associations were analyzed using logistic regression to estimate odds ratios (ORs) and 95% CIs. P values were obtained using likelihood ratio tests.
First, the univariable association between each clinical symptom/sign and M. genitalium infection was assessed. Then, for each clinical characteristic, a separate multivariable analysis was done to adjust for potential confounders, retaining only factors that acted as confounders (changing the crude OR by 10% or greater). Finally, a likelihood ratio test was carried out to assess whether each adjusted association was modified by HIV infection status (P < 0.10).
Informed consent was obtained from all study participants. The study was approved by the Science and Ethics Committee of the Ugandan Virus Research Institute and the Uganda National Committee for Science and Technology.
Characteristics of the Study Population
Details of the study population have been published previously.11 Briefly, out of the 1027 enrolled women, 96% reported engagement in sex work and 4% were employed in an entertainment facility. The median age of the women was 26 years (interquartile range, 22–30 years), and 90% had received no more than primary school education. The majority (70%) was formerly married (widowed, divorced, or separated), 8% were currently married or living as married, and 22% were single.
For the current study, 53 menstruating women and 2 women without endocervical samples at enrollment were excluded. Among the remaining 972 women, the prevalence of M. genitalium was 14% (95% CI: 12%–16%). Thirty-seven percent of the participants tested HIV-positive, 13% were diagnosed with NG, 9% with C. trachomatis, 18% with TV infection, and 55% with BV. M. genitalium was significantly more prevalent in HIV-positive than in HIV-negative women (18% vs. 12%, P = 0.01), in women infected with NG (24% vs. 13%, P = 0.002), with TV (20% vs. 13%, P = 0.02), and with BV (17% vs. 11%, P = 0.005) (Table 1).
Clinical signs and symptoms are shown in Table 2. The majority (60%) of women reported at least 1 symptom suggestive of a genitourinary tract infection at enrollment visit: 40% of the women complained of vaginal discharge, 11% of dysuria, and 38% of symptoms suggestive of PID. The prevalence of dysuria was the highest among women with M. genitalium in single or in coinfection, whereas vaginal discharge was most often reported by women with another STI than M. genitalium.
On clinical examination, 63% presented with signs suggestive of vaginal infection and 23% with endocervical mucopus. vaginal discharge syndrome and PID were diagnosed in 63% and 23% of the women, respectively. Women with M. genitalium infection presented more often with mucopurulent vaginal discharge, less frequent with profuse vaginal discharge and less frequent with mucopurulent endocervical discharge than those coinfected with another pathogen.
Clinical Characteristics Associated With M. genitalium Infection
On univariable analysis, reported dysuria was significantly associated with M. genitalium infection (OR: 1.85, 95% CI: 1.13–3.03), as was mucopurulent vaginal discharge (OR: 1.55, 95% CI: 1.06–2.29) (Table 2). Presence of a white vaginal discharge was less common in those with M. genitalium infection than those without (OR: 0.63; 95% CI: 0.42–0.96). There was no evidence of an association between other symptoms, cervical/vaginal signs or diagnosed STI syndromes, and M. genitalium infection (Table 3).
The crude ORs of the associations between each clinical characteristic and M. genitalium infection did not change by 10% or more after adjusting for age or any of the other STI (no confounding); therefore, no adjusted odd ratios could be presented. In addition, none of the associations varied by HIV status (P value for effect modification >0.10, data not shown).
This study examined the clinical correlates of M. genitalium infection among a population of women with a high prevalence of HIV and other STI in Uganda.
As the diagnosis of female urethritis is not routinely based on laboratory tests for the clinical management of STI in Uganda, reported dysuria was the only available indicator suggestive of urethritis in our study. The association of dysuria with M. genitalium infection remained after controlling for other STI and despite the fact that M. genitalium was not sampled from urine. Besides, dysuria was not associated with any of the other STI under investigation (data not shown). Our study is the first in Africa reporting such an association in women. Studies conducted among female STD clinic attendees in Western countries failed to find a significant association of symptomatically defined urethritis with M. genitalium.12–15 However, 3 large Scandinavian studies diagnosing urethritis microscopically from urethral smears also found a significant association with M. genitalium.13,16,17 Considering all the available data, it seems that M. genitalium may indeed cause urethritis in women, but further confirmatory studies using both clinical and laboratory methods are needed.
In our study, vaginal infection, defined as presence of profuse vaginal discharge and/or a change in the color (to whitish, yellow, or green) as found on speculum examination, was not associated with M. genitalium infection. This is most likely because presence of an abnormal amount of vaginal discharge on itself, regardless of the color, was not associated with M. genitalium. However, a significantly higher prevalence of M. genitalium was detected among women with yellow/green (mucopurulent) vaginal discharge and a significantly lower prevalence among those with whitish vaginal discharge, and these associations were not confounded by the presence of any other reproductive tract infections. No other clinical studies have documented similar detailed clinical findings.
The findings of Manhart et al that an elevated amount of PMNL (polymorphic mononuclear leucocytes) in vaginal smears was associated with M. genitalium (P = 0.04) supports the hypothesis that M. genitalium infection may indeed be a cause of vaginal infections.18
We diagnosed cervicitis if women presented with mucopurulent endocervical discharge on speculum examination. Our study did not find evidence of an association between M. genitalium and cervicitis. Results from other studies using a similar clinical definition of cervicitis were inconsistent; significant associations were reported by 2 studies conducted among female sex workers (adjusted OR: 1.6, 95% CI: 1.0–2.7 in West-Africa and OR: 2.2, 95% CI: 1.2–4 in Kenya),8,10 2 of the 4 studies conducted in women attending STD clinics12,14,18,19 and 2 of the 3 studies conducted in the general population.20–22 Also studies defining cervicitis based on microscopic findings (>10 PMNL in cervical smears) reported inconsistent results; 3 of the 4 studies found evidence for an association between M. genitalium and cervicitis.12,18,23,24 The clinical definition of cervicitis has a lower sensitivity compared with a definition based on objective microscopic findings, which calls again for further validation work.
Clinical PID defined as lower abdominal pain and/or dyspareunia confirmed by pain on bimanual palpation was not associated with M. genitalium in our study. Our results on clinical PID were in line with those reported from 2 community-based surveys15,25 and from the Kenyan sex workers cohort study9 but contrasted with the results from 2 case-control studies that found evidence of an association between clinical PID and M. genitalium26,27 and 2 studies confirming that M. genitalium was significantly more prevalent in histologically confirmed endometritis.28,29
In conclusion, M. genitalium infection is prevalent in women at high risk of HIV/STI in Uganda. Based on clinical symptoms and signs, our study showed evidence that M. genitalium is associated with urethritis and with vaginal infections, but not with cervical infections or PID. Our observations support earlier studies showing that M. genitalium infection may lead to clinically relevant genitourinary disorders and should be treated. In the absence of sensitive screening tests, further work is needed to validate clinical findings as possible indicators for M. genitalium infection in different populations to guide a possible syndromic approach for its management.
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