Microbiological flora in men with non-gonococcal urethritis with particular reference to anaerobic bacteria.

In a microbiological study of the urethral flora in men with non-gonococcal urethritis (NGU), Chlamydia trachomatis (isolated from 30% of men) was the only organism isolated significantly more often from men with NGU than controls (P less than 0.01). Bacteroids species, especially of the melaninogenicus-oralis group, were the predominant anaerobic bacterial isolate from both men with NGU (isolated from 24%) and controls (isolated from 30%). There was no evidence that aerobic bacteria, anaerobic bacteria or herpes simplex virus made a significant contribution as primary pathogens in non-chlamydial NGU. Gram-positive cocci were the only anaerobic organism isolated more often from chlamydia-positive men (29%) than chlamydia-negative men (16%) with NGU (P less than 0.01). The significance of this remains unclear.