Mycoplasma genitalium: trouble before we begin?
Description of the case: JH was a 26 year old male presenting with a clear urethral discharge and dysuria after recent azithromycin treatment (1 gm stat po) for a urethral Chlamydia trachomatis (CT) infection (First void urine (FVU) PCR positive). His proof of cure (POC) FVU at four weeks was CT negative. Two weeks later he presented to B2 Clinic visit with persistent non-specific urethritis (NSU) (discharge and dysuria) and was treated empirically with doxycycline 100mg bd for ten days, advised to abstain from sex and booked for follow-up in two weeks.
Subsequent laboratory results showed Mycoplasma genitalium (FVU-PCR) (Neisseria gonorrhoea/CT PCR negative) with a negative urethral smear (no white cells/organisms, culture negative). At two weeks his symptoms had improved and he was booked for POC. His subsequent POC FVU PCR was positive for M. genitalium. He was seen one week later and the treating clinician discussed the persisting M.genitalium infection and treatment options, viz Moxifloxacin versus an extended azithromycin regime. As a keen sportsman, the patient was very cautious about using Moxifloxacin and the risk of archilles tendinitis.
Despite concerns of selective macrolide resistance given his azithromycin pre-treatment, the patient preferred to trial the extended Azithromycin regime. Four weeks after ceasing treatment he completed a proof of cure (FVU-PCR) for M. genitalium; it was positive. One week later he was commenced on moxifloxacin 400mg od for 7 days. We are currently awaiting his proof of cure.
Questions for discussion: 1) How common is M. genitalium macrolide resistance and what are its drivers? 2) Is moxifloxacin appropriate for widespread use as a second line treatment? 3) What impact will M. genitalium macrolide resistance have on current empiric non-specific urethritis (NSU) treatment protocols?
Literature review: The literature review will focus on current treatment data for M. genitalium urethral infections including azithromycin 1g stat, extended azithromycin (500gm stat then four days of 250mg od) and moxifloxacin and the impact of pre-treatment on drug resistance development. Fluoroquinolone resistance and cost will also be reviewed, as well as moxifloxacin side effects. Literature deficits will also be discussed in the context of changing empiric NSU protocols.
