The prevalence of Mycoplasma genitalium coinfection in women with chlamydial infection was low and no patient characteristics predicted coinfection, according to data published in Sexually Transmitted Diseases.

Testing for M genitalium was performed via real-time polymerase chain reaction testing on samples obtained from 302 women infected with Chlamydia trachomatis who were seen at a clinic for sexually transmitted infections in Birmingham, Alabama, between March 2012 and September 2017. Women with gonorrhea, HIV, syphilis, who were pregnant, presently immunosuppressed due to illness or medical treatment, or who received antibiotics with anti-chlamydial activity in the previous 30 days were excluded from the study.

Patient characteristics were as follows: 93% black; median age 22 years (range, 16–50 years); median of 1 sexual partner in the last 3 months (range, 0–10); 42.1% were taking hormonal contraception; 48.7% with prior C trachomatis infection, by self-report or medical record review; 52.3% did not have urogenital symptoms; 18.9% had cervicitis; 2.7% had pelvic inflammatory disease; 28.8% had bacterial vaginosis, 12.6% had vulvovaginal candidiasis, and 3.6% had Trichomonas vaginalis infection.

M genitalium was detected in 7.3% of the 302 women, and none of the patient characteristics demonstrated predictability of infection. Of the 22 women presenting with M genitalium at baseline, 14 had wild-type strains while 8 had strains with macrolide resistance–associated mutations. Of these patients, 21 presented for a 3-month follow-up, of whom 6 were positive for M genitalium; all strains had macrolide resistance–associated mutations; in 5 patients this mutation was present at baseline, while 1 had a wild-type strain at baseline.

The lack of associations found in the study was possibly a result of small sample sizes. Also, while the study included data on M genitalium macrolide resistance–associated mutations, it did not evaluate quinolone-associated resistance mutations. Investigators also noted that the macrolide resistance–associated mutations strains found at baseline and follow-up in 5 of the 6 women suggest this resistance as a cause of treatment failure. It is also possible that a higher load of M genitalium at the time of treatment may also contribute to treatment failure, according to investigators.

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The single patient with a wild-type strain before treatment and a macrolide resistance–associated mutations strain post-treatment also suggested that azithromycin therapy may have selected for such a mutation. In addition, 2 of 7 women with macrolide resistance–associated mutations strains at baseline were negative at follow-up, indicating that treatment was effective or there was spontaneous clearance.

Investigators concluded that, in this cohort of women with chlamydia, M genitalium coinfection occurred infrequently. While they did not identify any associated patient characteristics, it was noted that data from other studies suggest that prevalence of coinfection may depend on the population being investigated. Further, 29% of women had repeat detection of M genitalium at follow-up, which, “likely reflected failure due to their [M genitalium] strains having MRMs.”

Reference

Harrison SA, Olson KM, Ratliff AE, et al. Mycoplasma genitalium coinfection in women with Chlamydia trachomatis infection. Sex Transm Dis. 2019;46:e101-e104.