As previously noted, urinary tract infection in men analogous to acute uncomplicated cystitis in women is uncommon in men younger than 50 years. When it does occur, men should never be treated with short-course therapy because of a high rate of early relapse. In men older than 50 years with urinary tract infection, tissue invasion of the prostate and possibly the kidneys should be assumed, even in the absence of overt signs of infection at these sites. However, relapse is common. Recurrent infection in men usually connotes a sustained focus within the prostate that has not been eradicated by previous courses of therapy.
Several factors make eradication of prostatic foci difficult.
Many antimicrobial agents do not diffuse well across the prostatic epithelium into the prostatic fluid, where the infection lies. The prostate may harbor calculi, which can block drainage of portions of the prostate gland or act as foreign bodies around which persistent infection can be hidden. As a result of these factors, it is now recognized that intensive therapy for at least four to six weeks, and as long as 12 weeks, is required to sterilize the urinary tract in many infected men. Prolonged treatment with any of these drugs has a greater than 60 percent chance of eradicating infection. Most of the failures result either from the anatomic factors listed above or from infection by E. faecalis or Pseudomonas aeru ginosa, two organisms that cause a particularly high rate of relapse after treatment with the antimicrobial agents currently employed.