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Extended M. genitalium urethritis therapy does not improve patient outcomes
Researchers found that 1.5 g of azithromycin extended over 5 days was no more effective than a single, 1-g dose for the treatment of Mycoplasma genitalium urethritis. In addition, the extended therapy did not reduce macrolide resistance, according to recent study findings.
“A single dose of azithromycin 1g has been a common treatment for [nongonococcal urethritis (NGU)]; however, since 2006, multiple countries have reported increasing failure rates for azithromycin 1 g for infections due to M. genitalium,” Tim R.H. Read, from the Central Clinical School at Monash University, Melbourne, Australia, and colleagues wrote. “In October 2013, Melbourne Sexual Health Centre (MSHC) began treating men with NGU with a 5-day course of azithromycin 1.5 g (500 mg stat followed by 250 mg daily for 4 days) to determine if it improved cure rates by reducing the rate of emergence of [macrolide resistance mutations (MRM)] during treatment.”
Read and colleagues compared the outcomes of patients with M. genitalium urethritis in Melbourne who received 1 g of azithromycin in 2012 to 2013 with those of patients who received 1.5 g of azithromycin over 5 days in 2013 to 2015. They used quantitative PCR specific for M. genitalium DNA on samples 14 to 100 days posttreatment to determine microbiological cure.
According to the results, there was no significant difference in cure rates between patients who received extended azithromycin therapy (58%; 95% CI, 49-68) vs. a single, 1-g dose (52%; 95% CI, 42-62). Cure rates were similar between the treatment arms among those with presumed macrolide sensitive infections (82% vs. 82%), and wildtype infections with posttreatment resistance mutations (12% vs. 18%). However, the researchers observed a greater incidence of existing pretreatment resistance in 2013 to 2015 compared with 2012 to 2013 (52% vs. 44%).
“These findings raise the question whether continued widespread use of azithromycin for NGU, in either dosage regimen, will result in a gradual increase in the proportion of macrolide-resistant M. genitalium infections,” Read and colleagues wrote. “Alternative classes and combinations of antibiotics are required for M. genitalium, and the development of rapid point of care tests, and tests that identify MRM, will improve our selection and stewardship of available antibiotics.” – by Savannah Demko
Disclosure: Read and two other researchers report that their institution received funding from SpeeDx Pty Ltd.