Differential association of ureaplasma species with non-gonococcal urethritis in heterosexual men

Abstract

Objective: To assess the role of Ureaplasma urealyticum and Ureaplasma parvum in patients with non-gonococcal urethritis (NGU) using specimens from a previously reported study of NGU.

Methods: Species-specific PCR assays for U urealyticum and U parvum were used to detect these organisms in specimens from men enrolled in a case-control study based in a Seattle STD clinic in order to evaluate their association with NGU. Urethritis was defined by clinical examination and the presence of inflammation on Gram stained smear. Controls had normal examination findings and no evidence of inflammation on Gram stain smear or by the leucocyte esterase test.

Results: U urealyticum was detected in 26% (31/119) of cases and 16% (19/117) of controls, resulting in an association with NGU (adjusted odds ratio (aOR)=2.3, 95% CI 1.04 to 4.9) after adjusting for age, race, history of prior urethritis and other NGU pathogens (Chlamydia trachomatis, Mycoplasma genitalium). The association of U urealyticum and NGU was strongest in white men <28 years of age (OR=5.4, 95% CI 1.3 to 22.2). U parvum was detected in 14% (17/119) cases and 31% (36/117 controls) and thus was negatively associated with NGU (aOR=0.4, 95% CI 0.2 to 0.8). The prevalence of U urealyticum (16%) in controls was higher than that of C trachomatis (3.4%) or M genitalium (4.3%, p<0.05, each comparison).

Conclusions: Unlike U parvum, U urealyticum was associated with urethritis. The strong effect in younger white men and high rates in controls may suggest variability in virulence among U urealyticum strains or in host innate or acquired immunity.

Figure 1

Undifferentiated Ureaplasma spp (formally designated Ureaplasma urealyticum) culture and U urealyticum and Ureaplasma parvum PCR results reported as indicated by case–control study phase (original or current study). *Specimens were not available from two case participants for evaluation by species-specific PCR assays in this study. Both participants were negative for U urealyticum by culture in the original study. **Available urine specimens from all participants were tested by species-specific PCR assays. In addition, these PCR assays were performed on urethral swab specimens from men whose urine specimens were ureaplasma culture positive and species-specific PCR negative, as indicated in the text.