A Randomized Comparison of Azithromycin and Doxycycline for the Treatment of Mycoplasma genitalium-Positive Urethritis in Men

Background. Several uncontrolled observational studies have suggested that the tetracycline class of antibiotics may not be effective in treating Mycoplasma genitalium infection. The present study compared the efficacy of 1 g of azithromycin given as a single dose with that of 100 mg of doxycycline given twice a day for 7 days in eliminating M. genitalium infection. Methods. Men with signs or symptoms of urethral disease who were attending a New Orleans sexually transmitted disease clinic and who met clinical criteria for nongonococcal urethritis were enrolled in the study. They were randomized to receive either doxycycline ( 100 mg orally twice a day for 7 days) or azithromycin ( 1 g orally as a single dose). All participants were asked to return for a follow-up visit 10-17 days after enrollment. M. genitalium-positive men at enrollment were invited to return for a second follow-up visit between 31 and 41 days after enrollment. Results. Of the 398 men who enrolled, 197 were randomized to receive azithromycin, and 201 were randomized to receive doxycycline. Thirty-six (18%) and 42 (21%) men in these 2 groups, respectively, were infected with M. genitalium. At the early initial follow-up visit, 3 (13%) of 23 azithromycin-treated men were M. genitalium positive, compared with 17 (55%) of 31 doxycycline-treated men (P = .002). Of 15 persistently infected men who were clinically cured at the early initial follow-up visit, 7 (47%) experienced clinical relapse over the subsequent 2-6 weeks. Conclusions. A single 1-g dose of azithromycin is more effective than multidose doxycycline for the treatment of M. genitalium-associated urethritis in men. M. genitalium may be an important cause of recurrent nongonococcal urethritis after administration of the treatment regimens currently recommended by the Centers for Disease Control and Prevention.