Current concepts in antimicrobial therapy of prostatitis.

Acute prostatitis usually is caused by aerobic gram-negative organisms or, to a lesser extent, the enterococci. The treatment of acute prostatitis requires the use of an antimicrobial with the appropriate spectrum for ten to fourteen days. However, treatment of chronic prostatitis is a more difficult therapeutic problem because of the relative impermeability of the noninflamed prostate to the majority of antimicrobial agents. The organisms most commonly responsible for chronic prostatitis include the aerobic gram-negative organisms, as well as chlamydia. Chlamydia may be the sole pathogens, or may be found as a copathogen with gram-negative organisms. Relatively few antibiotics have the appropriate physiochemical characteristics to penetrate the subacutely inflamed prostate. The most important determinant of tissue penetration in chronic prostatitis is the lipid solubility of the antibiotic, to a lesser extent its pKa (ionization potential), and the molecular size of the antibiotic. In general, penicillins, cephalosporins, and aminoglycosides do not penetrate well into the chronically inflammed prostate tissue. At the present time, the preferred agents in treating chronic prostatitis are trimethoprim or doxycycline. Doxycycline has the advantage of being active against chlamydia as well as the usual organisms that are responsible for chronic prostatitis. Therapy should be continued for two to three months.