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Prostate Abscesses and Staphylococcus aureus Bacteremia

Coronal reformation of pelvic computed tomography, portal phase, revealing several small hypodense structures in the prostate with enhancing margins (arrows), consistent with prostatic abscesses.

A 55-year-old man with poorly controlled type 2 diabetes was admitted with 8 days of lower urinary tract symptoms, including burning micturition and frequency, and 2 days of fever and rigors. Examination was normal, except for fever (38.5°C) and tachycardia. No loin tenderness or penile discharge was found, and digital rectal examination showed +1 elastic, nontender prostate. The patient’s white blood cell count was 13.9 × 109 cells/L, and he had normal hemoglobin and platelets, hyperglycemia, no acute kidney injury, normal urinalysis (twice), and erythrocyte sedimentation rate of 65 mm/hour. Chest x-ray and abdominal ultrasound were normal (prostate volume 22 mL). Two blood cultures grew Staphylococcus aureus (S aureus) sensitive to methicillin. Fever persisted. Echocardiography (transesophageal) was normal, as was a bone scan. Chest and abdominal computed tomography (CT) revealed prostatic abscesses, the largest being 15 × 22 mm (Figure). Cefamezine 2 g 3 times per day given over 4 weeks, together with transrectal ultrasound–guided needle aspiration (yielding pus with Gram-positive cocci), led to full recovery.

Our patient presented with an acute febrile illness, rigors, and S aureus bacteremia with normal urinalysis and digital rectal examination, so, despite the preceding lower urinary tract symptoms, the CT discovery of prostatic abscess came as a surprise. The patient did not belong to the known risk groups of S aureus bacteremia (eg, hemodialysis, injection drug use, human immunodeficiency virus or other immunosuppression, old age) and had no primary foci of infection, which in S aureus bacteremia usually include vascular catheter infection, skin or soft-tissue infection, chest or osteoarticular infection, and infective endocarditis.1 In ∼25% of cases, no primary focus is found, and an abscess could represent a metastatic infection acquired by hematogenous spread. This sequence is very rare in the prostate, however,2 and was not supported by this patient’s lower urinary tract symptoms preceding fever by days. In contrast, S aureus bacteremia secondary to prostatic abscess is well described.3

Prostate abscess develops as a rare complication of acute bacterial prostatitis.3, 4 Diabetes mellitus is a distinct risk factor for prostate abscess (P = .03), and S aureus infection is another, being 10 times as common compared to acute bacterial prostatitis without abscess.4 Gram-negative organisms are the major pathogens, and S aureusis seldom isolated.3, 4 Fever, perineal discomfort, dysuria, and possibly retention are common in the presentation, but the diagnosis of prostate abscess can be easily missed and is difficult without imaging (transrectal ultrasound or CT). Antibiotics must be able to overcome the blood–prostate barrier, so treatment must be prolonged and accompanied by a drainage procedure5 or surgery in most patients, especially when the collection measures >1 cm.

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-Ami Schattner, MD, Talya Finn, MBBS, Yair Glick, MD, Ina Dubin, MD

This article originally appeared in the October issue of The American Journal of Medicine.

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