Impact of Chlamydia trachomatis treatment with azithromycin or doxycycline on Mycoplasma genitalium in women

OBJECTIVES: In women being screened for Chlamydia trachomatis (CT) infection, Mycoplasma genitalium (MG) testing is not recommended. Among women positive for CT, studies reported that 7% to 28% had concurrent urogenital MG. The aim of this study was to investigate the impact on MG of a single 1-g dose of azithromycin or a 7-day course of doxycycline regimens as part of CT treatment. METHODS: MG was tested in vaginal swabs from the Chlazidoxy cohort collected at baseline and the 6-week follow-up visit after CT treatment. MG genotype and antibiotic resistance were analysed by sequencing the mgpB gene, and the parC, 23S and 16S rRNA genes. RESULTS: Among the 281 women included, 131 received azithromycin and 150 doxycycline. The proportion of MG-positive women was 16% (21/131) in the azithromycin group, and 12% (18/150) in the doxycycline group (P = 0.39). In each group, a similar proportion of macrolide (11.1% vs 26.7%, P = 0.37), and quinolone (11.7% vs 16.7%, P = 1) resistance-associated mutations were detected. Six weeks after treatment initiation, azithromycin eradicated MG in 85.7% (18/21) of the cases and doxycycline in 55.6% (10/18) (P = 0.07). CONCLUSION: In asymptomatic women infected with CT, the treatment with azithromycin or doxycycline eradicated MG in the majority of the cases.