164 CHAPTER 5 Infections and inflammatory conditions

Periurethral abscess

This can occur in patients with urethral stricture disease, in association with gonococcal urethritis and following urethral catheterization. These conditions predispose to bacteria (gram-negative rods, enterococci, anaerobes, gonococcus) gaining access through Buck fascia to the periurethral tissues. If not rapidly diagnosed and treated, infection can spread to the perineum, buttocks, and abdominal wall.

The majority (90%) of patients present with scrotal swelling and a fever. Up to 20% will have presented with urinary retention, 10% with a urethral discharge, and 10% having spontaneously discharged the abscess through the urethra.

The abscess should be incised and drained, a suprapubic catheter placed to divert the urine away from the urethra, and broad-spectrum antibiotics commenced (gentamicin and cefuroxime) until antibiotic sensitivities are known.

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166 CHAPTER 5 Infections and inflammatory conditions

Prostatitis: epidemiology and classification

Prostatitis is infection and/or inflammation of the prostate.

Classification of prostatitis

Given the variation in the descriptions of prostatitis clinically, in 1999 the National Institutes of Health (NIH) developed a classification system for prostatitis:1

IAcute bacterial prostatitis (ABP)

Acute and chronic bacterial (NIH I and II) forms of prostatitis are defined by documented bacterial infections of the prostate.

Chronic pelvic pain syndrome (NIH III) is characterized primarily by urological pain complaints in the absence of urinary tract infection.

Asymptomatic inflammatory prostatitis (NIH IV) is the incidental finding of prostatic inflammation on a biopsy specimen without any specific symptoms.

Epidemiology

The most common type of prostatitis is NIH III chronic pelvic pain syndrome, accounting for 90–95% of cases of prostatitis. Acute and chronic bacterial prostatitis (NIH I and II) each makes up another 2–5% of cases.

Pathogenesis

The tissues surrounding the prostatic acini become infiltrated with inflammatory cells (lymphocytes). The most common infective agents are gramnegative Enterobacteriaceae (Escherichia coli, Pseudomonas aeruginosa, Klebsiella, Serratia, Enterobacter aerogenes). From 5% to 10% of infections are caused by gram-positive bacteria (Staphylococcus aureus and saprophyticus, Streptococcus faecalis).

The etiology of inflammatory and noninflammatory forms of prostatitis is not well understood. Theories include the presence of functional or structural bladder pathology failure of the external sphincter to relax during voiding or some form of primary bladder neck obstruction.

Appropriate prostatic antimicrobial choice is critical because the prostate has an epithelial lining and a pH gradient that inhibits antimicrobials from entering the acini. The best agents have a high dissociation constant that allows diffusion of their unionized components into the prostate. If the antibiotic is basic, it can concentrate much higher in prostatic fluid because of the pH gradient.