Abstract: Objective To assess the association of U.urealyticum biovars (or gene clusters) 1 and 2 with male urethritis.Methods Four hundred and two subjects were recruited in a case-controlled, cross sectional study.Three pairs of primers were used to separate the gene clusters of U.urealyticum.Resuits There was no significant difference in the positive rate of U.urealyticum among Group G1 (patients with nongonococcal urethritis,NGU),Group G2 (STD clinic clients without NGU) and Group G4 (healthy volunteers) before ureaplasmas were typed.U.urealyticum (biovar 2 or gene cluster 2) was found significantly more often in G1 and G2 than that in G4 (P=0.003,G1 vs.G4;P=0.009,G2 vs.G4; respectively),but was not significantly different between G1 and G2 (P=0.704).However,The colonization rate of U.pravum was lower in G1 and G2 than that in G4 (P=0.000,G1 vs.G4;P=0.004,G2 vs. G4;respectively),but was not significantly different between G1 and G2 (P=0.380).When chlamydial infection was excluded,no significant difference was found in the colonization rate of U.urealyticum among G1,G2 and G4;but the rates of Up between G1 and G4 (P=0.004),G2 and G4 (P=0.005) were of significant difference.There was significant difference in the colonization rate of U.urealyticum (biovar 2 or gene cluster 2) between G2 and G4 (P=0.01).The pattern of colonization of U.pravum and U.urealyticum (biovar 2 or gene cluster 2) in G3 (men who have sex with men) was different from that in the heterosexual men with the prevalence rates of 3.63 % and 14.54%,respectively,Conclusions This study suggests that U.urealyticum (biovar 2 or gene cluster 2) colonization is not correlated with NGU,but rather with high risk sexual behavior.The presence of U.pravum in male urethra might be the result of normal colonization and is,therefore,unlikely to play any role in the development of NGU.

Key words: Urcaplasma urealyticum, Men who have sex with men, Urethritis