Etiologies of nongonococcal urethritis: bacteria, viruses, and the association with orogenital exposure

The purpose of the present study was to determine pathogens and behaviors associated with nongonococcal urethritis (NGU) and the usefulness of the urethral smear in predicting the presence of pathogens.

We conducted a case-control study of men with and without symptoms of NGU. Sexual practices were measured by questionnaire. First-stream urine was tested for Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma parvum, U. urealyticum, herpes simplex virus (HSV)-1, HSV-2, adenoviruses, and Gardnerella vaginalis by polymerase chain reaction.

C. trachomatis (20%), M. genitalium (9%), adenoviruses (4%), and HSV-1 (2%) were more common in cases with NGU (n = 329) after age and sexual risk were adjusted for (P< or =.01); U. urealyticum, U. parvum, and G. vaginalis were not. Infection with adenoviruses or HSV-1 was associated with distinct clinical features, oral sex, and male partners, whereas infection with M. genitalium or C. trachomatis was associated with unprotected vaginal sex. Oral sex was associated with NGU in which no pathogen was detected (P < or = .001). Fewer than 5 polymorphonuclear leukocytes (PMNLs) per high-power field (HPF) on urethral smear were present in 32%, 37%, 38%, and 44% of cases with C. trachomatis, M. genitalium, adenoviruses, and HSV, respectively.

We identified adenoviruses and HSV-1 as significant causes of NGU with distinct clinical and behavioral characteristics and highlighted the association between insertive oral sex and NGU. A urethral PMNL count of > or =5 PMNLs/HPF is not sufficiently sensitive to exclude pathogens in men with urethral symptoms.