Recent bacterial vaginosis is associated with the acquisition of Mycoplasma genitalium
Mycoplasma genitalium has been associated with adverse female reproductive tract outcomes such as cervicitis, pelvic inflammatory disease, infertility, pre-term birth, and HIV infection, yet little is known about factors predisposing women to acquiring M. genitalium. Bacterial vaginosis (BV) is the most prevalent female reproductive tract condition and has been associated with increased risk of acquiring several sexually transmitted pathogens, and may also be associated with M. genitalium.
Utilizing data from a prospective cohort of HIV positive and negative female sex workers in Mombasa, Kenya, we examined the relationship between recent BV and incident M. genitalium infection detected by a transcription mediated amplification assay (Hologic, Inc. San Diego, CA). At monthly clinic visits, women completed a sexual behavior interview and clinical examination, including collection of genital samples. Vaginal swab specimens from visits every other month were tested for M. genitalium. BV was defined on the basis of Nugent scoring (normal microbiota (scores 0-3), intermediate microbiota (scores 4-6), and BV (scores 7-10). A discrete time failure analysis for multiple events using logistic regression was used to estimate the odds of incident M. genitalium infection at follow-up visits in women with and without BV at the visit prior.
Two hundred eighty women contributed 2,454 visits for a total of 148.5 person-years at risk for acquiring M. genitalium. At baseline, 16.1% of women had prevalent M. genitalium infections, 40.4% had prevalent BV, and 18.2% had an intermediate microbiota. During follow-up, 50 women experienced at least one incident infection, for a total of 59 incident infections. The overall incidence rate of M. genitalium infection was 39.7 per 100 person-years and 43.3% (45/104) of the prevalent or incident M. genitalium infections were persistent, with an average duration of infection of 93 days. BV was detected at 38.3% (940/2,448) of visits and of these, women reported concurrent vaginal itching and/or discharge at only 8.4% (79/940) of visits. With adjustment for age and HIV status, prior BV was associated with a 3.5-fold increase in the odds of incident M. genitalium infection (aOR=3.49; 95%CI: 1.86, 6.55) and prior intermediate microbiota was associated with a modest, but not statistically significant, increase in odds (aOR=1.70; 95%CI: 0.69, 4.18). In the test for linear trend, the odds of incident M. genitalium infection increased by 16% for each increase in the Nugent score, after adjustment for age and HIV infection (aOR: 1.16, 95%CI: 1.07, 1.26).
These analyses suggest a strong association between BV and acquisition of M. genitalium. If recent BV increases susceptibility to M. genitalium, effective treatment of BV might have dual benefit, reducing both the female reproductive tract morbidity associated with BV, as well as reducing susceptibility to M. genitalium and the consequences of its sequelae.