Background In addition to its known microbiological aetiology, urethritis in men may be linked with other genital tract organisms, as yet unidentified in its pathogenesis. We used a microarray, with capacity to detect 22 genital tract organisms, in order to determine the association of symptomatic urethritis with infection or carriage of these organisms.

Methods 129 patients were asked to provide an extra first void urine specimen or give permission for their residual urine specimen submitted for Chlamydia trachomatis NAAT testing to be utilised. Patients were categorised into three self-reported symptom groups: definite symptoms of urethritis (discharge and/or dysuria), category 1(C1) n=80; non-specific symptoms of urethritis (eg, minimal urethral discomfort), category 2 (C2) n=26; and asymptomatic category 3 (C3) n=23. Total urine nucleic acid was extracted and subsequently used for PCR coupled microarray analysis. Organisms were defined as present or absent using an online data analysis method. In a pre-planned analysis, the following categories were compared for prevalence of organisms: C1 vs C2 and C3 combined; C1 and C2 combined vs C3 using Fisher's exact test.

Results One or more organisms were detected in 74% (n=95) of patients and two or more organisms in 33% (n=42). The prevalence of organisms known to cause urethritis in this largely symptomatic cohort was: 16% (n=21), 9% (n=12) and 5% (n=6) for C trachomatis, Mycoplasma genitalium and for Neisseria gonorrhoeae respectively. Escherichia coli was the most prevalent organism detected with a prevalence of 18% (n=23). The presence of M genitalium was statistically associated with C1 and C1 and C2 combined (p=0.03 and 0.01 respectively). In symptomatic patients, C trachomatis, Ureaplasma urealyticum, and Gardnerella vaginalis appeared to be more prevalent than in asymptomatics although not statistically significantly. Lactobacilli where detected in 1.3% and 4% of patients with C1 and C2 symptoms respectively, compared with 17% of asymptomatic patients. The absence of lactobacilli was associated with urethritis symptoms, either C1 alone or C1 and C2 combined (p=0.03 and p=0.01) respectively.

Conclusions Using a polymicrobial microarray approach we have demonstrated that symptomatic urethritis is associated with depletion of lactobacilli. This confirms early work using urethral swabs. The temporal nature of Lactobacilli depletion in relation to the onset of symptomatic urethritis needs to be investigated further.