Prostatic Abscess

Prostatic abscess is a collection of pus within the prostate gland, usually a complication of acute bacterial prostatitis.

• Organisms: Escherichia coli (most), Klebsiella, Pseudomonas, Proteus, Staphylococcus aureus (including methicillin resistant), Enterococcus, anaerobes; in endemic areas Mycobacterium tuberculosis, Burkholderia pseudomallei, Candida, Cryptococcus.
• Risk factors: diabetes mellitus (up to 70 percent in some series), HIV, immunosuppression, indwelling catheter, urethral instrumentation, prostate biopsy, benign prostatic hyperplasia with retention, chronic renal failure, recent urinary infection, haemodialysis, intravenous drug use.
• Incidence has fallen with early antibiotics, but diagnosis is frequently delayed.

Fever with chills, perineal, suprapubic or rectal pain, dysuria, frequency, urgency, hesitancy, weak stream, acute urinary retention (common), malaise.

• Digital rectal examination: tender, swollen, warm, boggy or fluctuant prostate (fluctuance seen in under half); do not massage the prostate.
• Differential diagnosis: acute bacterial prostatitis, epididymo-orchitis, pyelonephritis, perianal or ischiorectal abscess, prostate cancer, tuberculous prostatitis, bladder tumour, rectal abscess, urethral stricture.
• Complications: septicaemia and septic shock, rupture into the urethra, rectum, perineum or peritoneum, fistula formation, epididymitis, chronic prostatitis, sexual dysfunction, urinary retention, bacteraemia with metastatic abscess (vertebral, joint), death.

Urine microscopy and culture (midstream or catheter specimen), blood cultures, full blood count (leucocytosis), C-reactive protein, creatinine, glucose or HbA1c, HIV test, serum PSA (raised, interpret after resolution).

• Transrectal or transabdominal ultrasound shows hypoechoic or anechoic collection with septations.
• CT with contrast or magnetic resonance imaging confirms a rim-enhancing collection and spread to adjacent structures.
• Tuberculosis testing (urine acid fast bacilli, Xpert MTB/RIF), melioidosis culture in endemic areas, fungal cultures if immunosuppressed.
• Needle aspiration provides pus for culture.

Supportive: intravenous fluids, analgesia (paracetamol 1 g every 6 hours, diclofenac 75 mg IM when renal function allows), stool softeners (lactulose 15 mL twice daily), glycaemic control, bed rest.

Pharmacological

• Empirical intravenous therapy: ceftriaxone 2 g daily plus gentamicin 5 mg/kg daily (adjust to renal function), or piperacillin-tazobactam 4.5 g every 6 to 8 hours, or ciprofloxacin 400 mg every 12 hours; add vancomycin 15 to 20 mg/kg every 8 to 12 hours for suspected methicillin resistant Staphylococcus aureus; use meropenem 1 g every 8 hours for resistant organisms.
• Switch to oral ciprofloxacin 500 mg twice daily (or levofloxacin 750 mg daily, or cotrimoxazole 960 mg twice daily) when afebrile for 48 hours and drained; total duration 4 to 6 weeks.
• Melioidosis: ceftazidime 2 g IV every 6 to 8 hours or meropenem 1 g every 8 hours for 2 to 4 weeks, then cotrimoxazole 960 mg twice daily for 3 to 6 months.
• Tuberculous abscess: full anti-tuberculosis therapy for 6 months.
• Fungal abscess: fluconazole 400 to 800 mg daily.

Procedures

• Drainage for abscess above 1 to 2 cm or failure of antibiotics in 48 to 72 hours: transrectal or transperineal ultrasound guided needle aspiration (repeat if needed), or transurethral deroofing (unroofing) of the abscess under anaesthesia, or transperineal catheter drainage.
• Acute retention: suprapubic catheter (preferred) or a small urethral catheter placed gently.
• Prostatectomy is rarely needed for multiloculated or refractory abscess.

Special groups: diabetes (strict glucose control, insulin infusion in sepsis), HIV (antiretroviral therapy, look for opportunistic organisms), elderly (high mortality).

Red flags: septic shock, retention, abscess above 3 cm, immunosuppression, fluctuant perineal swelling, failure to improve in 72 hours.

Follow-up: repeat ultrasound at 2 to 4 weeks until resolution; urine culture after treatment; PSA at 6 to 8 weeks; evaluate for obstruction and underlying diabetes or HIV; assess for chronic prostatitis.