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Original Study

The Effect of Medical Male Circumcision on Urogenital Mycoplasma genitalium Among Men in Kisumu, Kenya

Mehta, Supriya D. MHS, PhD*; Gaydos, Charlotte DrPH; Maclean, Ian PhD; Odoyo-June, Elijah MBChB, MSc§; Moses, Stephen MD, MPH; Agunda, Lawrence DMLT§; Quinn, Nicole BS; Bailey, Robert C. PhD, MPH*

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Sexually Transmitted Diseases: April 2012 - Volume 39 - Issue 4 - p 276-280
doi: 10.1097/OLQ.0b013e318240189c
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Mycoplasma genitalium (MG) is a causative pathogen in urethritis, cervicitis, pelvic inflammatory disease (PID), and tubal factor infertility.13 In a meta-analysis of 19 studies, MG doubled the odds of HIV infection, and the association increased to 2.6 among studies conducted in sub-Saharan Africa.4 In South Africa, the prevalence of MG ranges from 2% to 17%, with highest prevalence among men and women with genital discharge or genital ulcers.58 Studies in western Africa found prevalences of 2% in the general population9; 12% to 18% in HIV infected or symptomatic persons10,11; and 26% in female sex workers.12 In eastern Africa, the prevalence of MG has been reported to be 3% to 5% in the general population in Tanzania,13,14 16% in female sex works in Nairobi, Kenya,15 and 17% in HIV-positive women in Mombasa, Kenya.16 No published studies have examined the association of male circumcision status with MG infection.

We determined the prevalence of MG and its association with circumcision status, sociodemographic characteristics, and behavioral factors among young men enrolled in a randomized trial of male circumcision to reduce HIV incidence in Kisumu, Kenya.

METHODS

Study Design and Participants

Between 2002 and 2005, our trial in Kisumu enrolled 2784 men aged 18 to 24 years. Trial recruitment, enrollment, reasons for refusing enrollment, and follow-up have been previously described.17 For inclusion, men had to be uncircumcised, HIV-negative, sexually active in the last 12 months, and aged 18 to 24 years; have a hemoglobin >9.0 mmol/L; and reside in Kisumu district. Exclusion criteria included foreskin covering less than half of the glans, a bleeding disorder, keloid formation, other conditions that might increase the risks of elective surgery, or a medical indication for circumcision. Following written informed consent, participants were randomized 1:1 to either immediate circumcision or delayed circumcision after a 2-year follow-up period (the control group). Both groups underwent risk reduction counseling for sexually transmitted infections (STIs) and HIV and were provided unlimited supplies of free condoms. Detailed evaluations were conducted at baseline, and at 1 month, 3 months, and every 6 months from randomization for both the circumcision and the control groups. The trial ended in December 2006, but follow-up continued until September 30, 2010. This study examines a cross-sectional sample of enrolled men, with specimens collected between July 16 and September 30, 2010.

The present study was approved by the institutional review boards of the University of Illinois at Chicago, the Kenyatta National Hospital, RTI International, The Johns Hopkins University, and the University of Manitoba.

Sexually Transmitted Infection and HIV Testing

For detection of Mycoplasma genitalium, an aliquot of first void urine was placed in the appropriate GEN-PROBE Specimen Transport Media for the APTIMA transcription-mediated amplification (TMA)-based assay (GEN-PROBE, Inc, San Diego, CA). Aliquoted urine specimens were immediately frozen at −80°C. Specimens were shipped on dry ice to The Johns Hopkins University International STD Reference Laboratory for testing with our previously published methods using the TMA MG research use only assay.1,2 First void urine specimens were also tested for Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) by polymerase chain reaction (PCR) assay (AMPLICOR CT/NG Test, Roche Diagnostics, Montreal, Canada), for Trichomonas vaginalis (TV) by TMA, and for TV by culture (InPouch TV test, Biomed Diagnostics, Oregon). Men with urethral discharge had a urethral swab taken for detection of NG and CT by PCR and for detection of NG and TV by culture. Serum specimens were tested for syphilis antibody (rapid plasma reagin with TPHA confirmation) and herpes simplex virus type 2 (HSV-2) antibody (Kalon HSV-2 IgG ELISA, Kalon Biologic Limited, Aldershot, United Kingdom). Urine and urethral swab specimens were sent to the University of Nairobi, Department of Medical Microbiology for NG and CT PCR. HSV-2 and syphilis testing and culture for TV and NG were conducted at the UNIM (Universities of Nairobi, Illinois, and Manitoba) laboratory in Kisumu. All tests were conducted according to manufacturers' instructions.

Testing for HIV infection was conducted using a parallel double rapid test protocol, using Determine HIV 1/2 (Abbott Diagnostic Division, Hoofddorp, The Netherlands), and the Uni-Gold Recombigen HIV Test (Trinity Biotech, Wicklow, Ireland). Men with concordant positive results were informed of their HIV status and followed-up at the study clinic or at the New Nyanza Provincial Hospital. Men who were concordant negative were eligible for the trial.

Data Collection

All consenting participants underwent standardized medical examination and history, and personal interview to obtain sociodemographic and health information and to assess behavioral risk factors. Interviews were conducted by trained, experienced, local language-speaking counselors in the participant's language of choice, English, Dholuo, or Kiswahili.

Data Analysis

The outcome for this analysis was infection with MG. Explanatory variables included demographic characteristics, sexual behaviors, postcoital cleaning, penile trauma, circumcision status, HSV-2 serostatus, and current and prior nonulcerative STI infection. We used circumcision status (as treated analysis) rather than treatment assignment (intention to treat) because randomization ended in 2006, and since then men have been free to choose to become circumcised if they wish. A cross-sectional sample of men was tested based on resource availability. To assess potential selection bias, we compared demographics, sexual behaviors, and STIs between men who were tested for MG and those who were not.

Differences between categorical explanatory variables and the outcome were assessed by the χ2 test or Fisher exact test when cell size was <5. Variables significant at the P < 0.10 level by likelihood ratio testing from univariate logistic regression were entered into multivariable logistic regression using a stepwise procedure with forwards selection for entry, and likelihood ratio testing for backwards elimination. Those variables with a likelihood ratio P < 0.05 were maintained in the multivariable model. Wald test P values are presented for the final multivariable model. Data were analyzed using STATA/SE 11.0 for Windows (Stata Corp., College Station, TX).

RESULTS

Study Sample

From June 13 to September 30, 2010, 526 men were tested for MG. Compared with men being followed but who were not included in the current protocol, men who underwent MG testing were more likely to be aged 26 to 31 than aged 23 to 25 (42% vs. 34%, P = 0.006) and married/cohabiting (60% vs. 46%, P < 0.001), but did not differ with regard to education, circumcision status, sexual behaviors, HIV prevalence, or baseline or cumulative ulcerative and nonulcerative STI incidence (results not shown; available from authors). Participants were 67.3% circumcised, 59.8% married or cohabiting, 5.9% HIV-positive (Table 1).

T1-6
Table 1:
Factors Associated With Mycoplasma genitalium Infection

MG Infection

MG was detected in 52 men (9.9%; 95% CI: 7.3%–12.4%). We traced and treated 46 (88%) of 52 men with oral azithromycin 1g. The majority (98.1%) of men with MG were asymptomatic (Table 1). Dysuria was reported by 1 (1.9%) man with MG and 8 (1.7%) men who were uninfected. There were no examination findings or complaints of genital ulcers (past 6 months, current symptoms) or testicular pain or swelling in any of the men.

Prevalence of Other STIs and Coinfections

Date matched results to assess coinfection with CT and NG were available for 85% (n = 445) of men. Infection with CT was 1.3% (95% CI: 0.3%–2.3%), and was more common among men infected with MG than those who were not infected (5.8% vs. 0.8%, Fisher exact P = 0.024; Table 2). The prevalence of NG was 1.4% (95% CI: 0.3%–2.4%) and did not differ by MG infection status. There was 1 (0.2%) culture-detected TV infection out of 14 TV infections detected by urine TMA (2.67%; 95% CI: 1.3%–4.0%). TV infection did not differ by MG infection status. Infection with HSV-2 was 56.7% (95% CI: 52.4%–60.9%) and was more common among men infected with MG (71.2% vs. 55.1%, P = 0.026). NG, CT, or TV coinfection occurred in 5 (9.6%) MG infections. There was one case of syphilis detected in an uninfected, uncircumcised participant.

T2-6
Table 2:
Number and Percent of Coinfections by Pathogen

Univariate Factors Associated With MG Infection

The reported age of men at follow-up ranged from 23 to 30 years, and did not differ by MG status (Table 1). There were no significant differences at the P < 0.10 level between infected and uninfected men with regard to educational attainment at baseline, current marital status, or current residence in Kisumu district. The distributions of sexual risk behaviors were similar between infected and uninfected men with regard to number of sex partners, condom use at last sexual intercourse, having sex with a woman during her menses, and having sex with a woman the same day as meeting. Compared with uninfected men, a greater proportion of MG-infected men reported sex in exchange for money or gifts (10.2% vs. 4.5%, P = 0.085), and a lower proportion reported cleaning the penis ≤1 hour after last sexual intercourse (24.0% vs. 39.7%, P = 0.030). Infection with CT at trial enrollment (11.8% vs. 3.4%, P = 0.005) and cumulative CT infection over trial follow-up CT (26.9% vs. 15.8%, P = 0.043) were more common among MG-infected than uninfected men. Baseline and follow-up CT infection were correlated (r = 0.41), and had similar magnitude of crude association with MG infection (Table 1). Likelihood ratio testing showed that a combined variable of baseline or incident CT infection explained more variance than either variable alone, and this combined variable was used in multivariable regression.

Multivariable Logistic Regression: Factors Associated With MG Infection

In multivariable logistic regression (Table 3), circumcision nearly halved the odds of MG (adjusted odds ratio [aQR] = 0.54; 95% CI: 0.29–0.99). Other variables significant at the P < 0.05 level were HSV-2 infection (aOR = 2.05; 95% CI: 1.05–4.00), CT infection (aOR = 2.69; 95% CI: 1.44–5.02), and washing the penis ≤1 hour after sex (aOR = 0.47; 95% CI: 0.24–0.95). There were no significant 2-way interactions between any of these variables. Variables significant at the P < 0.10 level from univariate analysis that were not significant in multivariable analysis included exchange of sex for money or gifts and TV infection.

T3-6
Table 3:
Results of Univariate and Multivariable Logistic Regression: Factors Associated With Mycoplasma genitalium Infection, N = 513

DISCUSSION

The prevalence of MG in our cohort of young men in Kisumu, Kenya, was high (10%), and the majority was asymptomatic (98%). The odds of urethral MG were nearly halved for circumcised men compared with uncircumcised men, controlling for behavioral risks. We are not aware of other published reports of circumcision status and behavioral factors associated with MG in men to which we can compare our results.

In our trial18 and the male circumcision trial in South Africa,19 male circumcision did not protect against urethral NG, CT, or TV. In men, MG is considered primarily a urethral infection. However, a recent report of men with nongonococcal urethritis found that men with MG had more than a 4 times higher odds of balanoposthitis, controlling for CT, and ureaplasma.20 Horner et al suggest that MG may be capable of infecting the poorly keratinized foreskin,20 as in vitro study has demonstrated that MG can infect vaginal epithelial cells.21 Evaluation of the penile microbiome among participants in the circumcision trial in Uganda showed that circumcision led to a significant reduction in anaerobic and facultative anaerobic bacteria.22 As MG is a facultative anaerobe, this may explain how MG would be recovered more frequently in uncircumcised than circumcised men. In our study, while MG was detected in urine, these 2 mechanisms (susceptibility of the foreskin to infection, anoxic microenvironment) provide explanation as to how the foreskin could provide a reservoir for urethral infection in uncircumcised men.

We found that men who reported cleaning their penis shortly after their last sexual intercourse were less likely to be infected with MG. One of the mechanisms by which circumcision is thought to protect against genital ulcer disease23 and balanitis24 is through improved genital hygiene. Thus men with better genital hygiene may be reducing the MG reservoir, decreasing likelihood of urethral infection, and this may be expected to have greater impact for uncircumcised men. While the interaction term was not statistically significant (P = 0.19), for uncircumcised men, cleaning the penis ≤1 hour after intercourse had an OR of 0.28, and the OR was 0.68 for men who were circumcised.

In our study, HSV-2 seropositivity doubled the odds of MG infection. This association may represent an overlap in similar risk factors for these 2 sexually acquired infections. Another potential explanation is that MG was more likely to be detected among men with HSV-2, as men with HSV-2 may have greater inflammation, more persistent infection, or greater MG organism load. The effect of HSV-2 infection on detection of MG or on MG organism load has not been assessed. We are unaware of published studies reporting the effect of HSV-2 infection on the sensitivity and specificity of detection of NG, CT, or TV that may provide insight.

Infection with MG was associated with CT infection but not with NG or TV. This may be related to differences in risks for acquisition, with risks for CT and MG being more similar than risks for NG or TV. Two prospective cohort studies of female students in London25 and sex workers in Nairobi15 found more than a doubling of MG risk associated with incident CT adjusted for demographics, behavioral risks, and other STIs. In the study of sex workers in Nairobi, NG also increased the risk of MG. Among HIV-positive Kenyan women, MG organism burden was higher for women who were coinfected with CT but was not associated with NG infection.16 Broad acceptance of MG as a pathogenic STI is relatively recent. The overlapping epidemiology and potential biologic synergism between MG and other STIs have not been studied extensively and are not well-understood.

Most MG infections (98%) were asymptomatic. The proportion of MG infections that were asymptomatic among male STI clinic attendees in Scandinavia is 34 to 39%,26,27 while results from a mobile STI service in South Africa found that 90% of MG infections were asymptomatic.6 Although the implications of pathogenesis and transmission of these asymptomatic infections in men are unclear, a high prevalence of MG, even if largely asymptomatic in men, is a public health concern due to associated risks of upper reproductive tract infection in women.3 Determining the contribution of MG to upper genital tract infection among women in this region will be necessary for implementing the most efficacious treatment regimens.

TV was detected in 2.5% of men by urine TMA, in contrast with the one infection detected by urine culture. The sensitivity of culture for TV compared with TMA is ≤50%.28,29 Throughout our trial and extended follow-up of the cohort, we used culture to identify TV. In our 24-month analysis,18 the incidence of TV was 2.5 per 100 person-years. It is clear from the current results that our previous analysis significantly underestimated the burden of TV infection. Future research measuring TV should invest in sensitive, nucleic acid-based methods of detection, as this will have a significant impact on prevalence and identifying risks for infection, as well as examining TV as a risk factor for other outcomes, such as HIV and adverse pregnancy outcomes.

Limitations

As this was a cross-sectional sample, temporal bias is a potential concern. However, most of the variables evaluated (circumcision status, HIV and HSV-2 status, and previous nonulcerative STI infection status) were measured before detection of MG infection. Because 85% of circumcised men in this sample had been circumcised for at least 2 years before detection of infection, it is unlikely that men were circumcised in response to MG infection. While we have not identified significant differences between men who chose circumcision and those who remained uncircumcised after the trial ended with regard to age, number of recent sex partners, HSV-2 status, or nonulcerative STI,30 it is possible that the protective association observed between being circumcised and MG infection is confounded by factors associated with choosing circumcision. Although we were unable to test all men in the cohort for MG, those tested did not differ from those who were not tested with regard to behavioral risks, HIV status, or STI history, indicating that resource constraints did not produce significant selection bias.

CONCLUSIONS

Male circumcision approximately halved the odds of MG infection, adding to the benefits of male circumcision in preventing several sexually transmitted infections. The effects of male circumcision in reducing HPV, penile carriage of anaerobic bacteria, and genital ulcers are transferred to female sex partners.31,32 Because of its association with urethritis, cervicitis, and pelvic inflammatory disease, a reduction in MG through male circumcision is of public health importance to men and their female sex partners.

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