Macrolides are also used for treating urethritis and nongonococcal urethritis. Erythromycin and, more recently, azithromycin have been prescribed for the therapy of certain pelvic infections, usually those caused by Chlamydia trachomatis. Multidrug resistant gonococci have increased in prevalence. Fluoroquinolones are no longer recommended and recently high levels of resistance to azithromycin have been reported.
Macrolides have an added benefit for treating urethritis, as Chlamydia are frequently identified as co-pathogens or can also be found as the sole pathogen. Azithromycin has been used as a single dose of one gram but resistance is a growing problem. A dose of two grams of azithromycin is recommended except in the case of penicillin-allergic patients. Side effects such as nausea and vomiting due to this higher dose have led to compliance problems, and importantly the emergence of resistance is of concern.
Macrolides have been useful historically for treating the spectrum of organisms involved in gonococcal and nongonococcal urethritis including Ureaplasma and Mycoplasma species. Some Ureaplasma species have also gained macrolide and quinolone resistance. A well-tolerated new antibiotic with activity against these pathogens, specifically azithromycin and fluoroquinolone-resistant strains, would be well received.
Untreated syphilis during pregnancy can have devastating consequences such as stillbirth, neonatal death, or infant morbidity such as deafness or other significant neurologic sequelae. Congenital syphilis among infants less than one year old also increased 23% from 8.2 cases/100,000 live births in 2005 to 10.1 in 2008. Women of color and those living in the southern U.S. are disproportionately affected. Azithromycin has been used as a two gram single dose; however, resistance has been documented in California and elsewhere.