Prevalence of Infections Associated With Prostate Biopsy

It has been estimated that approximately 1 million transrectal ultrasound (TRUS)-guided prostate biopsies are done in both the United States and Europe each year.¹ Previous studies using administrative claims reported an increase in infection-related hospitalizations after biopsy over time in the United States and Canada.¹ However, these studies had limited data on important factors, such as culture results and the type of prophylaxis received, which might help shed light on potential ways to reduce this problem. Accordingly, several international groups have recently undertaken detailed studies on the prevalence of postbiopsy infections that include data on the type of antimicrobial prophylaxis and resistance patterns.

Infection Related Hospitalizations After Prostate Biopsy in a Statewide Quality Improvement Collaborative

Womble PR, Dixon MW, Linsell SM, et al. Michigan Urological Surgery Improvement Collaborative. J Urol. doi: 10.1016/j.juro.2013.12.026. [published online ahead of print December 15, 2013]

The goal of the study was to establish the rate of infection- related hospitalizations after prostate biopsy within the state of Michigan by the Michigan Urological Surgery Improvement Collaborative (MUSIC). This registry prospectively collects a variety of clinical data including detailed information on prostate biopsies. Quality assurance for the data collection is achieved by regular on-site audits of all participating practices.

For this study, exclusion criteria were individuals who were not a part of MUSIC practices and those practices who had performed fewer than 30 TRUS biopsies. A total of 3911 biopsies were ultimately included. Statistical analysis was used to examine the relationship between the type of antimicrobial prophylaxis and infection-related hospitalizations.

Consistent with previous studies, they reported a total hospitalization rate of 0.97% following prostate biopsy. Although the hospitalization rates varied between 0% to 4.2% among the various MUSIC practices, this difference was not statistically significant. Of these hospital admissions, 92% were infection related, and 91% of patients with cultures grew Escherichia coli. The remaining cultures grew Pseudomonas species. Overall, fluoroquinolone resistance was found in 79% of patients. The study did not find any statistically significant association between prior prostate biopsy, prebiopsy enema, or prostate size with the risk of infectious complications.

Overall, 96% of the patients had received a fluoroquinolone as antibiotic prophylaxis. Interestingly, patients given a different type of antibiotic prophylaxis that was not compliant with the American Urological Association guidelines were more significantly likely to have infection-related hospitalizations (P = .0026). The authors discuss the importance of adherence to guidelines as a simple first step, and also to consider local resistance profiles.

This study was limited by the fact that it only included a group of practices in the state of Michigan. Particularly due to geographic differences in antibiotic resistance, these results may not be generalizable to other locations. Additionally, information regarding the number of cores taken per biopsy and further details regarding hospitalizations (ie, intensive care unit admissions and other downstream issues) may have provided more insight.

Infective Complications After Prostate Biopsy: Outcome of the Global Prevalence Study of Infections in Urology (GPIU) 2010 and 2011, A Prospective Multinational Multicentre Prostate Biopsy Study

Wagenlehner FM, Van Oostrum E, Tenke P, et al. Eur Urol. 201363521–52722704727

The Global Prevalence Study of Infections in Urology examined the infective complications after prostate biopsy in 84 centers spanning five continents. The goal was to determine the prevalence of infection, as well as to identify specific risk factors. The investigators used an internet-based platform to collect data on baseline patient characteristics and follow-up data during the 2 weeks after biopsy, including urinary tract infection (UTI), hospital admission, urine cultures, and antibiotic treatment.

Overall, 702 men were included in the database. The vast majority (97.4%) underwent transrectal biopsy and received fluoroquinolone prophylaxis (90.8%). Postbiopsy follow-up data were available for 521 of the participants; 27 developed a symptomatic UTI (5.2%). Within this group, 16 required hospitalization (3.1%), and 10 of the UTIs were culture-positive. E coli was the isolated organism in 8 of the 10 cultures, and all 8 were resistant to fluoroquinolones. Statistical analysis did not reveal any subgroups at higher risk of developing infection. Parameters assessed included age, prostate size, PSA, history of UTI, preoperative bowel preparation, antibiotic prophylaxis, fluoroquinolone prophylaxis, and repeat biopsy.

This study is unique as it offers a glimpse at biopsyrelated infections across a very broad geographic area. Limitations of this study are rooted in its design. As the authors note, the cross-sectional nature of the study precluded the ability to analyze any changes in infective patterns over time. Furthermore, each site only contributed a median of four evaluable patients per year, and 2-week outcomes were only available in 74.2% of patients. Overall, the small sample size in many subgroups limited the statistical power to evaluate risk factors.

Both of these studies provide unique epidemiologic data on the prevalence of infections after prostate biopsy. They confirm that postbiopsy, infection-related hospitalizations are, in fact, a serious concern that must be discussed with patients undergoing the procedure. The majority of patients in both the Michigan and global surveys still receive fluoroquinolones as prophylaxis, but increases in resistance may require a shift in the protocol moving forward. Additional studies are necessary to examine the cost effectiveness of alternative options, such as expanded prophylaxis and targeted prophylaxis using rectal swab cultures.