Transrectal prostate biopsies carry the risk of infection. By using non-selective culture plates, instead of commonly used ciprofloxacin (CIP)-containing plates, we analyzed the association between Escherichia coli CIP minimal inhibitory concentration (MIC) and post-biopsy infectious complications. A pre-biopsy rectal swab was taken from 207 consecutive men, scheduled for transrectal 12-core prostate biopsy with CIP 750 mg as the mostly used prophylaxis. CIP MIC of rectal Gram-negative bacilli was determined from a chromogenic agar. Rectal E. coli were categorized to resistant (R) and intermediate (I) isolates together (R + I, MIC > 0.25 mg/l) and to sensitive (S, MIC ≤ 0.25 mg/l) using EUCAST clinical breakpoints. In addition, epidemiological cutoff (ECOFF R, MIC > 0.064 mg/l) was used for categorization. Eighteen (8.7%) men showed CIP R + I E. coli by the EUCAST breakpoints and 41 (19.8%) using the ECOFF R criteria. During follow-up, 15 (7.2%) men had infectious symptoms, of which 9 (4.3%) were culture-confirmed infections. Only 4 (26.7%) of these 15 patients showed R + I E. coli in the rectal swab according to EUCAST, but 10 (66.7%) using the ECOFF cutoff. Rectal E. coli CIP R + I by the EUCAST clinical breakpoints associated with infectious complications with OR 5.7 (95% CI 1.5-21.8, P = 0.005) and ECOFF R E. coli by OR 10.7 (95% CI 3.0-37.6, P < 0.001). Men carrying rectal E. coli with moderately lowered CIP susceptibility (MIC > ECOFF 0.064 mg/l) were identified and, interestingly, they showed a high risk of developing infectious symptoms after the biopsy. This explains why some men develop infectious complications despite appropriate antibiotics before prostatic biopsies.
European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology. 2018 Mar 02 [Epub ahead of print]
Inari Kalalahti, Kaisa Huotari, Kanerva Lahdensuo, Eveliina Tarkka, Henrikki Santti, Antti Rannikko, Anu Pätäri-Sampo
Department of Urology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. ., Department of Infectious Diseases, University of Helsinki and Helsinki University Hospital, Helsinki, Finland., Department of Urology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland., Department of Clinical Microbiology, University of Helsinki and Helsinki University Hospital, HUSLAB, Helsinki, Finland.