Health and Prostate

Chronic bacterial prostatitis is now recognized as an important cause of relapses of urinary tract infection in elderly men. It is most commonly caused by E. coli, but Klebsiella-Enterobacter, P. mirabilis, and enterococci are also common causes. S. epidermidis, S. aureus, and diphtheroids have been frequent isolates in some series. Many individuals with chronic infection of the prostate are totally asymptomatic. However, some have perineal discomfort, low back pain, or dysuria. Symptoms of acute urinary tract infection may periodically appear. In fact, chronic bacterial prostatitis is probably the most common cause of relapsing urinary tract infection in men. Fever, if present, tends to be low grade unless pyelonephritis occurs. Rectal examination and intravenous pyelograms are unremarkable unless the patient also has an enlarged prostate from benign prostatic hypertrophy or carcinoma.

Because of the focal nature of chronic bacterial prostatitis, needle biopsy of the prostate gland for culture of tissue is unreliable. Demonstration of leukocytes in prostatic fluid is not specific for bacterial prostatitis. There is a quantitative localization technique for making the bacteriologic diagnosis. Because bacteria present in the urethra can contaminate prostatic secretions obtained by prostatic massage, accurate diagnosis requires simultaneous quantitative cultures of urethral urine, midstream urine, prostatic secretions expressed by massage, and the urine voided after massage. An ejaculate is probably preferable to expressed secretions.

Specimens must be cultured immediately after collection, and methods of quantitating small numbers of bacteria must be used. The study should be done at a time the patient has no significant bacteriuria. If bacteriuria is present, ampicillin, cephalexin, or nitrofurantoin should be given for two to three days to sterilize the urine; these agents will not affect prostatic bacterial counts in chronic bacterial prostatitis. If chronic bacterial prostatitis is present, the number of bacteria in the expressed secretions or ejaculate will exceed those in urethral or midstream urine by at least 10-fold. If no secretions or ejaculate can be obtained, the bacterial counts in the postmassage specimen should be at least 10-fold higher than the urethral or midstream samples.

Chronic bacterial prostatitis is very difficult to cure because few antimicrobial agents penetrate the noninflamed prostate. Further, the nidus of infection in some patients may be small prostatic calculi that presumably are difficult to sterilize. Chronic bacterial prostatitis is therefore likely to persist and cause relapsing urinary tract infection. Unlike classical urinary tract infection, relapses may occur after long periods without bacteriuria (e.g., months). Transurethral prostatectomy is curative only if all the infected tissue is removed; about one third of patients will be cured by this procedure. Total prostatectomy is contraindicated because of the complications of sexual impotence and incontinence.

Until recently, medical therapy for patients who have chronic bacterial prostatitis consisted of treatment for bacteriuria followed by daily low dose suppressive antibacterial therapy. With these regimens, most patients remain relatively asymptomatic. However, the pathogen persists in the prostatic fluid cultures, and cessation of antibiotic therapy eventually results in relapse of urinary tract infection. Trimethoprim-sulfamethoxazole now appears to be the most effective therapy available for chronic bacterial prostatitis. Approximately one third of patients can be cured with prolonged therapy with this agent (i.e., two tablets given twice daily for 12 weeks). If this regimen fails, the patient should be managed either by treating acute exacerbations of urinary tract infection or by chronic suppressive therapy using low daily doses (e.g., half normal doses) of an antimicrobial agent.