Image: PD Prostate Histology
1. Serial repeat prostate biopsies may raise the absolute risk of infectious morbidity for patients by up to 15%.
2. Gentamicin is linked to much higher rates of post-procedure infection than flouroquinolones.
Evidence Rating: 2 (Good)
Study Rundown: Active surveillance with serial ultrasound guided transrectal prostate biopsies has become a preferred management strategy for millions of American men with low grade prostate cancer. Among the risks of this approach is a high rate of infection, often with antibiotic resistant bacteria. This study looked at infection rates following a single prostate biopsy. The primary outcome was infection within 14 days of procedure, as defined by hospitalization, positive blood or urine cultures, or fever over 100.3. While only a single biopsy was performed within the confines of the study, many of the participants had previous biopsies, which were referenced to analyze the effect of multiple biopsies on infection risk. It was determined that each previous biopsy increased the risk of infection by 1.33 times (p= 0.041, CI 1.01-1.74).
Lack of urine or blood cultures before biopsy limits the ability of this study to exclude asymptomatic infection prior to biopsy. Additionally, a wide variety of antibiotic prophylaxis regimens were used by providers which may have contributed to post-biopsy infection if some regimens are in fact less protective. A limited number of events prevented the use of multivariate analysis. Even so, this study identifies a possible additional risk associated with repeat biopsy and provides justification for further refinement of antibiotic prophylaxis protocols.
Relevant Reading: Controversies in transrectal ultrasonography and prostate biopsy
In Depth [prospective cohort study]: This study looked at 403 men who underwent a transrectal prostate biopsy at Memorial Sloan-Kettering Cancer Center between January 2011 and January 2012. The procedure performed was the standard 18-gague, 14 core biopsy. 14 patients (3.5%) experienced an infection following the biopsy. More than half (55%) of study participants had previous biopsy, although only 10% had four or more previous biopsies. The risk of post-procedure infection for men with two or less biopsies was 2%, a number which could increase to 15% for men with 5 or more biopsies. The study also analyzed the risk of infection for those patients given flouroquinolones (OR 0.19) versus gentamicin (OR 1.95).
By Adam Schatz and Chaz Carrier
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