Prostatic abscess: clinical features, management, and outcomes of a "Stealth" infection: retrospective case series and review of the literature

Abstract

Prostatic abscess (PA) is uncommon and may be difficult to distinguish from acute prostatitis which often leads to delayed or missed diagnoses. Although gram-negative bacilli are the traditional etiology of PA, Staphylococcus aureus is an emerging cause. The goals of this study were to characterize the current clinical features, microbiology, management, and outcomes of PA at a US academic center. A retrospective review of adult patients hospitalized with an ICD-9/10 diagnosis of PA between January 2013 and July 2018 was conducted. Inclusion criteria included age ≥18 years, a compatible genitourinary (GU) infection syndrome, and imaging consistent with PA. Relevant data were extracted and analyzed by univariate analysis as appropriate. Twenty-two patients with PA were identified with median age 57 years. Five patients (23%) were immunosuppressed and 11 (50%) had diabetes. No patient had prior PA but 3 had past prostatitis. Only 1 patient had recent GU instrumentation and none had indwelling urinary catheters. The most common presenting symptoms were fever (59%), dysuria (45%), and urinary retention (32%). Only 7 out of 18 (39%) patients had prostate tenderness on exam and none had fluctuance. As demonstrated by computed tomography, PAs were multifocal in 8 (36%) patients and 16 (73%) had PAs >2 cm in diameter. The median abscess size was 3.2 cm. S. aureus was isolated in 60% of positive urine cultures and 78% of positive blood cultures; 46% were methicillin-resistant. Nine patients (41%) received antibiotics alone whereas 13 (59%) required antibiotics plus drainage. The median duration of antimicrobial therapy was 34.5 days. Four week mortality was 9%. When comparing S. aureus PA to other causes, S. aureus patients tended to have higher fevers, more often had diabetes, and received longer durations of antibiotic therapy (median 35 days vs 31 days, P = 0.04) but age, abscess size, and mortality did not differ. PA is relatively uncommon and often clinically unsuspected. Imaging may be critical to accurate diagnosis. Optimal management usually requires antibiotics and sometimes drainage depending on abscess size. We found a significant proportion of cases due to S. aureus which might be relevant when deciding empiric antimicrobial therapy.

Keywords: Prostate; S. aureus; abscess; antimicrobial therapy; genitourinary infection.