Background The aetiology of non-gonococcal urethritis (NGU) is unexplained in 30–50% of cases. The role of ureaplasmas is not clear. We detected Ureaplasma urealyticum (Uu) and U parvum (Up) by quantitative PCR in the urine of men with and without NGU to show a possible association with urethritis.
Methods Urine samples from 158 male STD-clinic attendees with symptomatic NGU (>5 PMNL/hpf) and 77 asymptomatic men without NGU (<5 PMNL/hpf) were collected. The patient's age and number of partners within the previous 6 months were recorded. All samples were tested for Neisseria gonorrhoeae (Ng), Chlamydia trachomatis (Ct), Mycoplasma genitalium (Mg), Uu, Up, Trichomonas vaginalis (Tv), herpes simplex virus (HSV) 1 and 2, and adenovirus by real-time PCR.
Results Ct and Mg were found in 22 and 30% of NGU, respectively, and were associated with NGU (p<0.0001 both). Three had dual Ct and Mg infection. Uu was detected in 13% of NGU cases and 12% of controls (p>0.99). The median Uu bacterial DNA load was higher in men with NGU than in men without (223 genome equivalents (geq) and 10 geq, respectively; p=0.002). Using ROC-curve analysis to determine the optimal cut-off, patients with >53 geq were more likely to have urethritis (p=0.02). In men with NGU of unknown aetiology, there was no difference in the rate of Uu detection when compared to controls (p=0.26). The corresponding median Uu bacterial DNA load were significantly higher in this group than in controls (p=0.01), and using a cut-off of >53 geq, men with NGU of unknown aetiology were more likely to harbour Uu (14%) than were men from the control group (1%), (p=0.005). Up was detected in 14% of NGU cases and 19% of controls (p=0.34). There was no difference in the detection rate of Up or in the median Up bacterial load in any of the groups. HSV-1 was detected in 3% of cases and 1% of controls. HSV-2 was found in 2% of NGU cases. All urine samples were negative for adenovirus. Cases and controls had similar median number of partners within 6 months (2 partners) and age (28 and 29 years, respectively).
Conclusion The bacterial load of U urealyticum in men with NGU and in men with NGU of unknown aetiology was higher than in men without NGU, and the presence of >53 geq of Uu was associated with urethritis in both groups. In accordance with other studies, U parvum was not associated with urethritis. (Preliminary results were presented at the ASM general meeting, San Diego 2010).
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