Use of oral metronidazole HCl (Flagyl) for posturethritis syndrome

Six men with nongonococcal urethritis (NGU) who remained symptomatic after specific therapy with different antibiotic regimens were empirically treated with either of two regimens of oral metronidazole: 500 mg., three times a day for ten days, or 2.5 Gm. (10 x 250 mg.) orally in one dose. All patients had pretreatment seminal fluid cultures. No significant pathogen could be isolated. Side effects included generalized weakness, gastrointestinal symptoms, and a characteristic metallic taste. All patients became asymptomatic after therapy. The single-dose therapy seemed to be more effective in persistent cases. Since metronidazole is active only against anaerobic bacteria, it is postulated that currently unidentified anaerobic bacteria may play a role in at least some cases of posturethritis syndrome.