Background: Non-gonococcal urethritis is the most common clinical diagnosis for men seeking care at sexually transmitted disease clinics.

Objective: To identify the pathogens involved in NGU[1] among males attending an Israeli STD clinic.

Methods: During 19 months spanning September 1996 to July 1998 we investigated a cohort of 238 male patients attending the Bnai Zion Medical Center STD[2] clinic with a clinical presentation of urethritis. Intraurethral swab specimens were tested for Neisseria gonorrhea, Ureaplasma urealyticum, Mycoplasma hominis, and Trichomonas vaginalis by culture and for herpes simplex virus by antigen detection. First voiding urine for Chlamydia trachomatis was done by polymerase chain reaction. The specific seropositivities of HSV[3] types 1 and 2 were tested by enzyme-linked immunosorbent assay.

Results: From among 238 males with dysuria or urethral discharge an etiology for urethritis was found for 71 (29.8%). N. gonorrhea was recovered in only three men (4.2%). In the remaining 68 NGU patients C. trachomatis (35/68, 51.5%) and U. urealyticum (31/68, 45.6%) were the most common infecting and co-infecting pathogens (P < 0.0001). M. hominis and T. vaginalis were found in 9/68 (13.2%), and 1 patient, respectively. HSV was recovered from the urethra in 7/68 males (10.3%) – 3 with HSV-1, 2 with HSV-2, and 2 were seronegative for HSV. None of these males had genital lesions. Although a single etiologic agent was identified in 45/68 infected men (66.2%), co-infection was common: 2 organisms in 15 (22%) and 3 organisms in 8 (11.8%).

Conclusion: C. trachomatis and U. urealyticum were the most common infecting and co-infecting pathogens in this cohort of men with NGU. Unrecognized genital HSV infections are common in males attending our STD clinic and symptomatic shedding of HSV occurs without genital lesions. Still, the microbial etiology in this group remains unclear in many patients despite careful microbiologic evaluation.