Contaminated sponges as source of Klebsiella pneumoniae prostatitis outbreak after transrectal ultrasound-guided prostate biopsy

OBJECTIVES: The infection rates following transrectal ultrasound-guided (TRUS) prostate biopsy range from 1-5%, mostly caused by Escherichia coli. We investigated an abnormal increase in Klebsiella pneumoniae prostatitis rate following TRUS prostate biopsy in a urological surgery center. METHODS: The outbreak occurred in a 217-bed private hospital performing TRUS prostate biopsies. After an antibiotic prophylaxis (single 3 g dose of fosfomycin-trometamol 2 hours before the procedure), each biopsy was placed on a pre-impregnated sponge and then transferred to a plastic cassette for pathological analysis. The outbreak investigation relied on a retrospective analysis of cases defined as the occurrence of a urinary or systemic infection caused by K. pneumoniae within 7 days following a TRUS prostate biopsy, including a review of procedures and microbiological analysis. RESULTS: Between January 1 and March 31, 2024, 13/49 (27%) patients who underwent TRUS prostate biopsy developed clinical symptoms of prostatitis requiring hospitalization. The incidence rate was 20% (5/25, three with E. coli) from January 3 to February 20, 2024 and increased to 33% (8/24, seven with K. pneumoniae) from February 21 to March 31, 2024. During the investigation, K. pneumoniae strains isolated from clinical samples and moistened sponges were genotypically similar, confirming the latter as the source of infection. The pack of sponges in use was discarded, with sterilization of sponges and trays before their use. No other case of K. pneumoniae prostatitis was identified following these measures from April to December 2024. CONCLUSIONS: This investigation underlines the critical need for evaluation of practices around the preparation of sponges and cassettes in contact with the puncture needle when performing TRUS prostate biopsy.