Mycoplasma genitalium: another important pathogen of nongonococcal urethritis.

PURPOSE: We reviewed findings on the pathogenic role of Mycoplasma genitalium in nongonococcal urethritis and the treatment of men with M. genitalium positive nongonococcal urethritis.

MATERIALS AND METHODS: We reviewed literature selected from peer reviewed journals listed in MEDLINE and from resources cited in those articles from 1967 to January 2001.

RESULTS: M. genitalium was first isolated from 2 men with nongonococcal urethritis and thereafter it was shown to cause urethritis in subhuman primates inoculated intraurethrally. This mycoplasma has been detected significantly more often in patients with acute nongonococcal urethritis, particularly in those with nonchlamydial nongonococcal urethritis, than in those without urethritis. The prevalence of M. genitalium positive nonchlamydial nongonococcal urethritis is 18.4% to 45.5% of all nonchlamydial nongonococcal urethritis cases. In addition, the persistence of M. genitalium in the urethra after antimicrobial chemotherapy is associated with persistent or recurrent nongonococcal urethritis. M. genitalium is highly susceptible to tetracycline, macrolide and some new fluoroquinolones. The regimen of 100 mg. doxycycline orally twice daily for 7 days, which is recommended for chlamydial nongonococcal urethritis, seems to be effective for M. genitalium positive nongonococcal urethritis, although clinical data to substantiate this regimen are limited.

CONCLUSIONS: The various results reported to date tend to support the proposition that M. genitalium is a pathogen of nongonococcal urethritis. However, currently diagnostic methods for this important mycoplasma are not available in clinical practice. Because of the possible association of the posttreatment presence of M. genitalium in the urethra with persistent or recurrent nongonococcal urethritis, eradication of this mycoplasma from the urethra is essential for managing M. genitalium positive disease. However, clinical data on treating M. genitalium positive nongonococcal urethritis are extremely limited. Thus, further studies are required to develop new diagnostic methods that would be available in clinical settings and establish a new treatment algorithm for nongonococcal urethritis, including M. genitalium positive disease.