Resistance-guided treatment of Mycoplasma genitalium infection at a UK sexual health centre.

We evaluated the ResistancePlus® MG assay in providing macrolide resistance-guided treatment (RGT) for Mycoplasma genitalium infection at a UK sexual health centre. M. genitalium-positive samples from men with urethritis and women with pelvic inflammatory disease (PID) were tested for macrolide resistance-mediating mutations (MRMMs). MRMM-positive infections were given moxifloxacin 400 mg; otherwise 2 g azithromycin (1 g single dose and then 500 mg OD) was given. Among 57 M. genitalium-positive patients (32 men and 25 women), MRMMs were detected in 41/57 (72% [95% confidence interval (95% CI) 58-83%). Thirty-two of 43 patients given RGT attended for test of cure. Treatment failure rate was significantly lower at 1/32 (3%) than 10/37 (27%) before RGT (n = 37 [men = 23 and women = 17]; p = 0.008). Treatment failure was lower in male urethritis (0/15 vs. 7/21 p = 0.027) but not in female PID. There was a trend of a shorter time to negative test of cure (TOC) in male urethritis (55.1 [95% 43.7-66.4] vs. 85.1 [95% CI CI 64.1-106.0] days, p = 0.077) but not in female PID. Macrolide resistance is higher than previous UK reports and higher than expected. RGT reduces overall treatment failure and is particularly beneficial in M. genitalium urethritis. Fluoroquinolone resistance will continue to rise with increasing fluoroquinolone use, and RGT is critical to direct appropriate azithromycin use and prevent overuse of moxifloxacin.