Fluoroquinolone and Macrolide Resistance-Associated Mutations in

Mycoplasma genitalium is a significant sexually transmitted pathogen, causing up to 25 % of cases of nongonococcal urethritis in men, and it is strongly associated with cervicitis and pelvic inflammatory disease in women. Currently, the usual first-line treat-ment is the macrolide antibiotic azithromycin, but an increasing incidence of treatment failure over the last 5 years suggests the emergence of antibiotic resistance. The mutations responsible for macrolide resistance have been found in the 23S rRNA gene in numerousM. genitalium populations. A second-line antibiotic, the fluoroquinolone moxifloxacin, was thought to be a reliable alternative when azithromycin began to fail, but recent studies have identified mutations that may confer fluoroquinolone resis-tance in the genes parC and gyrA. The aim of this study was to determine the prevalence of antibiotic resistance inM. genitalium in Sydney, Australia, by detecting relevant mutations in the 23S rRNA gene, parC, and gyrA. M. genitalium-positive DNA ex-tracts of specimens, collected from patients attending sexual health clinics in Sydney, were tested by PCR amplification and DNA sequence alignment. The 186 specimens tested included 143 initial patient specimens and 43 second, or subsequent, specimens from 24 patients. We identified knownmacrolide resistance-associated mutations in the 23S rRNA gene in 43 % of the initial pa-tient samples andmutations potentially associated with fluoroquinolone resistance in parC or gyrA sequences in 15 % of the ini-tial patient samples. These findings support anecdotal clinical reports of azithromycin andmoxifloxacin treatment failures in Sydney. Our results indicate that further surveillance is needed, and testing and treatment protocols forM. genitalium infec-tions may need to be reviewed