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Clin Infect Dis. 2017 Feb 1;64(3):250-256. doi: 10.1093/cid/ciw719. Epub 2016 Oct 24.

Azithromycin 1.5g Over 5 Days Compared to 1g Single Dose in Urethral Mycoplasma genitalium: Impact on Treatment Outcome and Resistance.

Author information

Central Clinical School, Monash University, and
Melbourne Sexual Health Centre, Alfred Health, Melbourne, Australia.
Central Clinical School, Monash University, and.
Murdoch Childrens Research Institute, Parkville, Victoria, Australia.
Department of Obstetrics and Gynaecology, University of Melbourne.
Department of Microbiology and Infectious Diseases, the Royal Women's Hospital, and.
Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia.



We evaluated the impact of extended azithromycin (1.5g over 5 days) on selection of macrolide resistance and microbiological cure in men with Mycoplasma genitalium urethritis during 2013-2015 and compared this to cases treated with azithromycin 1g in 2012-2013.


Microbiological cure was determined for men with M. genitalium urethritis treated with azithromycin 1.5g using quantitative polymerase chain reaction specific for M. genitalium DNA on samples 14-100 days post-treatment. Pre- and post-treatment macrolide resistance mutations were detected by sequencing the 23 S gene.


There was no difference in proportions with microbiological cure between azithromycin 1.5g and 1g: 62/106 (58%; 95% confidence interval [CI], 49%, 68%) and 56/107 (52%; 95%CI 42-62%), P = .34, respectively. Also, there was no difference in the proportion of wild-type 23 S rRNA (presumed macrolide sensitive) infections cured after 1.5g and azithromycin 1g: 28/34 (82%; 95%CI 65-92%) and 49/60 (82%; 95%CI 70-90%), P=1.0, respectively. There was no difference between 1.5g and 1g in the proportions of wild-type infections with post-treatment resistance mutations: 4/34 (12%; 95%CI 3-27%) and 11/60 (18%; 95%CI 10-30%), respectively, P = .40. Pre-treatment resistance was present in 51/98 (52%; 95%CI 42-62%) cases in 2013-2015 compared to 47/107 (44%; 95%CI 34-54%) in 2012-2013, P = .25.


Extended azithromycin 1.5g was no more effective than a single 1g dose at achieving cure of M. genitalium urethritis and importantly did not reduce the selection of macrolide resistance. Nonmacrolide and new approaches for the treatment of M. genitalium urethritis are required.


Mycoplasma genitalium; azithromycin; macrolide resistance.; nongonococcal urethritis

[Indexed for MEDLINE]

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