Risk factors for urethritis in heterosexual men. The role of fellatio and other sexual practices

BACKGROUND: Nonchlamydial nongonococcal urethritis (NGU) is a common sexually transmitted disease (STD) in heterosexual men. Prior studies have suggested that NGU may be acquired by insertive oral sex. GOAL: To assess the association of oral sex and other sexual practices with nonchlamydial NGU in heterosexual men in order to better understand this syndrome and to guide its prevention and treatment. Risk factors for urethral gonorrhea and chlamydial infection were explored to contrast with NGU. STUDY DESIGN: A retrospective case-control study was conducted among heterosexual men attending as STD clinic during 1993 and 1994. The study included 4,848 men who were sexually active within the prior 2 months and had urethral specimens obtained for Gram's stain, culture for Neisseria gonorrhoeae, and culture for Chlamydia trachomatis. RESULTS: Insertive oral sex was not shown to be an independent risk factor for NGU. Independent predictors of nonchlamydial NGU by multivariate analysis included African-American race (odds ratio OR] 3.71, 95% confidence interval 95% CI] 3.06 to 4.50) and having > or = two sex partners in the prior 2 months (OR 1.45, 95% CI 1.20 to 1.75). History of using condoms "always" was negatively associated with NGU (OR 0.59, 95% CI 0.43 to 0.79), gonorrhea (OR 0.31, 95% CI 0.17 to 0.56), and chlamydial infection (OR 0.67, 95% CI 0.44 to 1.03). CONCLUSIONS: This study supports the sexually transmitted nature of nonchlamydial NGU but did not confirm an association with oral sex. However, the analysis was compromised by the rarity of insertive oral sex as patients' only sexual exposure. Consistent condom use protects against all causes of sexually acquired urethritis.