A re-appraisal of treatment in chronic bacterial prostatitis.

The pH of normal human expressed prostatic secretion in 136 samples from 93 men was 7.28 +/- 0.04. In 41 samples from 14 patients with documented chronic bacterial prostatitis the alkalinity of prostatic fluid was increased 10-fold (1 pH unit) and was 8.32 +/- 0.07. We believe these studies account for the failure of trimethoprim to eradicate human bacterial prostatitis effectively despite the experimental data documenting diffusion and concentration of trimethoprim in the acidic prostatic fluid of the normal dog. The factors governing drug diffusion into the prostate and the influence of pH on the concentration of trimethoprim in the expressed prostatic secretion are discussed.