The most common types of prostatitis include acute and chronic bacterial prostatitis, nonbacterial prostatitis, and prostatodynia. Chronic bacterial prostatitis, caused mainly by coliform bacteria, is a common cause of relapsing recurrent urinary tract infection in men. About 90% of men with prostatitis have nonbacterial prostatitis or prostatodynia. Because nonbacterial forms of prostatitis have no recognized infectious cause, therapy using antimicrobial agents is ineffective and unwarranted.