Transperineal Prostate Biopsy is Associated With Lower Tissue Core Pathogen Burden Relative to Transrectal Biopsy: Mechanistic Underpinnings for Lower Infection Risk in the Transperineal Approach.

OBJECTIVE: To understand the mechanistic basis for reduced infectious complications in transperineal (TP) prostate biopsy, we sought to determine whether TP prostate biopsy is associated with a lower degree of pathogen introduction into the prostate relative to transrectal (TR) biopsy. MATERIALS AND METHODS: In men scheduled for prostate biopsy for standard clinical indications, rectal and perineal skin swabs, and 2 extra biopsy cores, were obtained. Specimens underwent DNA extraction followed by next-generation sequencing and standard laboratory culture. Microbial quantity and composition were determined and compared between prostate core biopsy tissue from individuals who underwent TP vs TR biopsy. RESULTS: Twenty-three men were accrued to the study. Biopsy core tissue from the TP group had less microbial diversity (15.0 vs 25.8 phylogenetic clades/sample, P = .0004) and had a lower quantity of known pathogens (36.3 vs 104.2 normalized counts of pathogens/sample, P = .018) relative to the TR group. TP group tissue core flora was more attributable to the perineal than rectal source (P = .047). Viable Escherichia coli was isolated from 45% of the TR group cores, but none in the TP group (P = .014). CONCLUSION: Biopsy tissue from individuals who undergo TP biopsy harbors a lower human pathogenic bacterial load than those who undergo TR biopsy, with a minimal risk of viable E. coli. Our results elucidate a possible mechanism for reduced infectious risk associated with TP biopsy relative to TR biopsy and a rational basis for widespread implementation of TP biopsy.