Objectives Mycoplasma genitalium is an important cause of STI in men and women. Worldwide evidence suggests a reduction in efficacy of azithromycin treatment due to the prevalence of macrolide resistant M. genitalium. The aim of this study was to describe the prevalence of macrolide resistance in patients with a positive test for M. genitalium within our setting.

Methods Two STI clinics in Stockholm offered tests for M. genitalium as part of a routine care pathway. Positive specimens were analysed for macrolide resistance mediating mutations by sequencing.

Results During the study period, 171 (7.5%) of 2276 patients had a positive M. genitalium test; 7% of women and 8% of men. Macrolide resistance was detected in 31 (18%) of the M. genitalium positive; treatment with azithromycin within the previous 6 months was strongly associated with macrolide resistance.

Conclusions The prevalence of macrolide resistance was lower in Sweden than in other Northern European settings. We hypothesise that this observation may be due to use of doxycycline as primary treatment of Chlamydia trachomatis. The efficacy of empirical treatment is challenged by azithromycin resistant M. genitalium. Clinically available and enhanced diagnostics targeting this pathogen are urgently required. We suggest a test of cure 3–4 weeks after start of azithromycin therapy since macrolide resistance develop during treatment.