Mycoplasma genitalium Infection in Sub-Saharan Africa: How Big Is the Problem?

Quantitative Real-Time Polymerase Chain Reaction for the Diagnosis of Mycoplasma genitalium Infection in South African Men With and Without Symptoms of Urethritis

BACKGROUND

This study was done to diagnose Mycoplasma genitalium infection based on bacterial load in urine specimens from symptomatic and asymptomatic men.

METHODS

Urine specimens from 94 men with visible urethral discharge, 206 with burning on micturition and 75 without symptoms presenting to a family practitioner were tested for M. genitalium as well as Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis by transcription-mediated amplification assays. A quantitative polymerase chain reaction assay was used to determine the bacterial load for all specimens in which M. genitalium was the only organism detected.

RESULTS

Among the 375 specimens collected, M. genitalium was detected in 59 (15.7%) men (both symptomatic and asymptomatic) using the transcription-mediated amplification assay, and in 45 (12.0%) of the total population, it was the only pathogen detected. One or more pathogens were detected in 129 (43%) of the symptomatic men, with N. gonorrhoeae in 50 (16.7%); C. trachomatis in 37 (12.3%) and T. vaginalis present in 24 (8.0%) patients. Among the 17 patients where mixed infections were detected, M. genitalium with N. gonorrhoeae was the most common (11/17; 64.7%). Patients with visible urethral discharge had significantly higher M. genitalium concentrations than those with burning on micturition. The median M. genitalium load in symptomatic men was significantly higher than that in asymptomatic men.

CONCLUSIONS

This study confirms the high prevalence of M. genitalium among men with urethritis in South Africa and demonstrates that there is a strong association with M. genitalium bacterial load and clinical urethritis. As the number of organisms increased, the severity of the symptoms increased, an indication of the role that the organism plays in disease progression.

Prevalence and Correlates of Genital Infections Among Newly Diagnosed Human Immunodeficiency Virus-Infected Adults Entering Human Immunodeficiency Virus Care in Windhoek, Namibia

BACKGROUND

Identifying and treating genital infections, including sexually transmitted infections (STI), among newly diagnosed human immunodeficiency virus (HIV)-infected individuals may benefit both public and individual health. We assessed prevalence of genital infections and their correlates among newly diagnosed HIV-infected individuals enrolling in HIV care services in Namibia.

METHODS

Newly diagnosed HIV-infected adults entering HIV care at 2 health facilities in Windhoek, Namibia, were recruited from December 2012 to March 2014. Participants provided behavioral and clinical data including CD4+ T lymphocyte counts. Genital and blood specimens were tested for gonorrhea, Chlamydia, trichomoniasis, Mycoplasma genitalium, syphilis, bacterial vaginosis, and vulvovaginal candidiasis.

RESULTS

Among 599 adults, 56% were women and 15% reported consistent use of condoms in the past 6 months. The most common infections were bacterial vaginosis (37.2%), trichomoniasis (34.6%) and Chlamydia (14.6%) in women and M. genitalium (11.4%) in men. Correlates for trichomoniasis included being female (adjusted relative risk, [aRR], 7.18; 95% confidence interval [CI], 4.07-12.65), higher education (aRR, 0.58; 95% CI, 0.38-0.89), and lower CD4 cell count (aRR, 1.61; 95% CI, 1.08-2.40). Being female (aRR, 2.39; 95% CI, 1.27-4.50), nonmarried (aRR, 2.30; (95% CI, 1.28-4.14), and having condomless sex (aRR, 2.72; 95% CI, 1.06-7.00) were independently associated with chlamydial infection. Across all infections, female (aRR, 2.31; 95% CI, 1.79-2.98), nonmarried participants (aRR, 1.29; 95% CI, 1.06-1.59), had higher risk to present with any STI, whereas pregnant women (aRR, 1.16, 95% CI 1.03-1.31) were at increased risk of any STI or reproductive tract infection.

Apparently-Different Clearance Rates from Cohort Studies of Mycoplasma genitalium Are Consistent after Accounting for Incidence of Infection, Recurrent Infection, and Study Design

Mycoplasma genitalium is a potentially major cause of urethritis, cervicitis, pelvic inflammatory disease, infertility, and increased HIV risk. A better understanding of its natural history is crucial to informing control policy. Two extensive cohort studies (students in London, UK; Ugandan sex workers) suggest very different clearance rates; we aimed to understand the reasons and obtain improved estimates by making maximal use of the data from the studies. As M. genitalium is a sexually-transmitted infectious disease, we developed a model for time-to-event analysis that incorporates the processes of (re)infection and clearance, and fitted to data from the two cohort studies to estimate incidence and clearance rates under different scenarios of sexual partnership dynamics and study design (including sample handling and associated test sensitivity). In the London students, the estimated clearance rate is 0.80p.a. (mean duration 15 months), with incidence 1.31%-3.93%p.a. Without adjusting for study design, corresponding estimates from the Ugandan data are 3.44p.a. (mean duration 3.5 months) and 58%p.a. Apparent differences in clearance rates are probably mostly due to lower testing sensitivity in the Uganda study due to differences in sample handling, with 'true' clearance rates being similar, and adjusted incidence in Uganda being 28%p.a. Some differences are perhaps due to the sex workers having more-frequent antibiotic treatment, whilst reinfection within ongoing sexual partnerships might have caused some of the apparently-persistent infection in the London students. More information on partnership dynamics would inform more accurate estimates of natural-history parameters. Detailed studies in men are also required.

Mycoplasma genitalium infection: current treatment options, therapeutic failure, and resistance-associated mutations

Mycoplasma genitalium is an important cause of non-gonococcal urethritis, cervicitis, and related upper genital tract infections. The efficacy of doxycycline, used extensively to treat non-gonococcal urethritis in the past, is relatively poor for M. genitalium infection; azithromycin has been the preferred treatment for several years. Research on the efficacy of azithromycin has primarily focused on the 1 g single-dose regimen, but some studies have also evaluated higher doses and longer courses, particularly the extended 1.5 g regimen. This extended regimen is thought to be more efficacious than the 1 g single-dose regimen, although the regimens have not been directly compared in clinical trials. Azithromycin treatment failure was first reported in Australia and has subsequently been documented in several continents. Recent reports indicate an upward trend in the prevalence of macrolide-resistant M. genitalium infections (transmitted resistance), and cases of induced resistance following azithromycin therapy have also been documented. Emergence of antimicrobial-resistant M. genitalium, driven by suboptimal macrolide dosage, now threatens the continued provision of effective and convenient treatments. Advances in techniques to detect resistance mutations in DNA extracts have facilitated correlation of clinical outcomes with genotypic resistance. A strong and consistent association exists between presence of 23S rRNA gene mutations and azithromycin treatment failure. Fluoroquinolones such as moxifloxacin, gatifloxacin, and sitafloxacin remain highly active against most macrolide-resistant M. genitalium. However, the first clinical cases of moxifloxacin treatment failure, due to bacteria with coexistent macrolide-associated and fluoroquinolone-associated resistance mutations, were recently published by Australian investigators. Pristinamycin and solithromycin may be of clinical benefit for such multidrug-resistant infections. Further clinical studies are required to determine the optimal therapeutic dosing schedules for both agents to effect clinical cure and minimize the risk of emergent antimicrobial resistance. Continual inappropriate M. genitalium treatments will likely lead to untreatable infections in the future.