Long duration of asymptomatic Mycoplasma genitalium infection after syndromic treatment for nongonococcal urethritis.

Background. Although Mycoplasma genitalium (MG) is an acknowledged cause of nongonococcal urethritis (NGU), access to diagnostic testing is limited. Syndromic management is common, yet little is known about natural history. Methods. Between August 2014 and April 2016, 13 heterosexual men aged >= 16 years with MG were identified within a cohort study of men with and without NGU attending an urban sexually transmitted diseases clinic. Men had 6-7 monthly visits. NGU was defined as >= 5 polymorphonuclear leukocytes per high-power field on urethral Gram stain plus either visible urethral discharge or urethral symptoms. Men with NGU received 1 g of azithromycin. Men with persistent NGU received moxifloxacin 400 mg for 14 days. First-void urine was retrospectively tested for MG using transcription-mediated amplification. Resistance-associated mutations were detected by polymerase chain reaction (PCR) and sequencing. Organism load was determined by quantitative PCR. Results. Sixty-two percent of MG-positive men had macrolide resistance-mediating mutations (MRMM) at enrollment; 31% had parC mutations (all outside the quinolone resistance-determining region). MG persisted after azithromycin in 7 men, 6 of whom had MRMM. The median duration of persistence in the absence of curative therapy was 143 days (range, 21-228). Five men experienced symptom resolution after azithromycin, but MG persisted for another 89-186 days before moxifloxacin. Organism load was somewhat lower in MRMM than wild-type infections (P = .16) Conclusions. The high prevalence of macrolide resistance and long duration of infection after symptom resolution highlights the need for diagnostic MG testing of men with NGU to direct therapy.