Some authors describe acute bacterial prostatitis as a self-limiting disease, and as with any other acute septic condition, parenteral broad-spectrum antibiotic therapy is indicated. Chronic bacterial prostatitis, however, is associated with a causative organism persisting unaltered in prostatic fluid and leading to relapsing urinary tract infections. In the 1970s, several workers produced a classification system and bacteriologic localization cultures for establishing the diagnosis of prostatitis. Krieger and Crawford point to an important factor that is omitted in many clinical trials with episodes of chronic bacterial prostatitis in men. If localization studies of the prostate infection are attempted in the presence of bacteriuria, the urine must be sterilized with nitrofurantoin or penicillin G. Urine cultures obtained from first-voided urine, bladder urine, and urine voided after prostatic massage should show no growth, and the expressed prostatic secretion can then be examined for evidence of prostatic infection. This procedure reduces the contamination of the expressed prostatic secretion by the organism from the urinary tract infection. This is important, because antibiotic treatment is determined by the sensitivity of the organism isolated from the prostate as well as by the ability of the antibiotics to penetrate the prostate. Meares outlines the pharmacokinetic features needed for drug diffusion into prostatic fluid and provides detailed information on the physical characteristics of the prostate during acute and chronic bacterial prostatitis. Unfortunately, the choice of an ideal drug cannot be extrapolated from this information because pharmacodynamic principles cannot predict clinical efficacy. Some authors find that sulfamethoxazole-trimethoprim has the best cure rate in the treatment of chronic bacterial prostatitis.(ABSTRACT TRUNCATED AT 250 WORDS)