Introduction Macrolide resistance in Mycoplasma genitalium(MG) is of growing concern in countries where azithromycin is used to treat non-gonococcal urethritis(NGU) but UK data is lacking. Patients with NGU or pelvic inflammatory disease (PID) are routinely tested for MG at our clinic and offered test of cure (TOC) 4 weeks post-treatment. We aim to determine rates of MG-positivity 4 weeks after treatment and their associations.

Methods Notes of MG-positive cases between December 2015 and November 2016 were reviewed and data collected on management.

Results 114 cases of MG were identified. 91(80%) were symptomatic and 12(11%) were MG contacts. Should be 52/339(15%) men with NGU and 15/160(9.4%) women with PID were MG-positive.

80/114(78%) were given an azithromycin regimen first line. 59/114(53%) returned for TOC and 24/59(40%) were positive (23 following azithromycin; 1 following moxifloxacin). 19 returned for a second TOC and 14 were negative (1 following azithromycin and 13 following moxifloxacin second line). 5/19(26%) were positive (3 following azithromycin and 2 following moxifloxacin second line). One male patient with confirmed resistance to macrolide and quinolone therapy achieved microbiological cure with pristinamycin.

Having a positive TOC was significantly associated with risk of reinfection (p=0.01) and being symptomatic at TOC (p<0.001), but not significantly associated with gender, sexual orientation, HIV status, concurrent STI (p=0.053) and azithromycin use.

Discussion MG-positivity rates at 4 week TOC are high raising concerns of treatment failure although re-infection may also contribute. As commercial assays are imminently available, diagnoses of MG will increase and where possible should be accompanied by antimicrobial resistance testing.