The molecular mechanisms of fluoroquinolone resistance found in rectal swab isolates of Enterobacterales from men undergoing a transrectal prostate biopsy: the rationale for targeted prophylaxis

Abstract

Background Transrectal ultrasound-guided prostate biopsy (TRUS-Bx) is considered an essential urological procedure for the histological diagnosis of prostate cancer. It is, however, considered a “contaminated” procedure which may lead to infectious complications. Recent studies suggest a significant share of fluoroquinolone-resistant rectal flora in post-biopsy infections. Methods The molecular mechanisms of fluoroquinolone resistance, including PMQR (plasmid-mediated quinolone resistance) as well as mutation in the QRDRs (quinolone-resistance determining regions) of gyrA, gyrB, parC and parE, among Enterobacterales isolated from 32 of 48 men undergoing a prostate biopsy between November 2015 and April 2016 were investigated. Before the TRUS-Bx procedure, all the patients received an oral antibiotic containing fluoroquinolones. Results In total, 41 Enterobacterales isolates were obtained from rectal swabs. The MIC of ciprofloxacin and the presence of common PMQR determinants were investigated in all the isolates. Nine (21.9%) isolates carried PMQR with qnrS as the only PMQR agent detected. DNA sequencing of the QRDRs in 18 Enterobacterales (E. coli n = 17 and E. cloacae n = 1) isolates with ciprofloxacin MIC ≥ 0.25 mg/l were performed. Substitutions in the following codons were found: GyrA—83 [Ser → Leu, Phe] and 87 [Asp → Asn]; GyrB codon—605 [Met → Leu], ParC codons—80 [Ser → Ile, Arg] and 84 [Glu → Gly, Met, Val, Lys], ParE codons—458 [Ser → Ala], 461 [Glu → Ala] and 512 [Ala → Thr]. Six isolates with ciprofloxacin MIC ≥ 2 mg/l had at least one mutation in GyrA together with qnrS. Conclusions This study provides information on the common presence of PMQRs among Enterobacterales isolates with ciprofloxacin MIC ≥ 0.25 mg/l, obtained from men undergoing TRUS-Bx. This fact may partially explain why some men develop post-TRUS-Bx infections despite ciprofloxacin prophylaxis.

Characterization of Salmonella spp. in a tertiary hospital during 2019-2021 in Nanjing, China: Focusing on the clonal dissemination of Salmonella Enteritidis ST11

“…This could be con rmed by the mutations found in these isolates, where double mutations occurring both in gyrA (D87N and S83F) and parC (T57S and S80I/S80R) lead to uoroquinolone-resistance in Salmonella strains. Of note, we found that only a single mutation in gyrA (D87Y) or parC (T57S) was associated with an elevated Minimum Inhibitory Concentration (MIC) value [45], however, not lead to uoroquinolone resistance in the remaining 34 isolates without PMQRs. Meanwhile, the presence of single mutation in the remaining 34 uoroquinolone-non-resistant strains also means that, once they acquired more mutations or PMQRs, resistance to uoroquinolone could be easily acquired, since PMQR determinants may result in an increase in mutations of topoisomerase [46].…”

Prevalence of Plasmid-Mediated Quinolone Resistance (PMQRs) Determinants and Whole Genome Sequence Screening of PMQR-Producing E. coli Isolated from Men Undergoing a Transrectal Prostate Biopsy

“…Studies have suggested that the agricultural use of antimicrobial agents increased the number of human infections caused by drug-resistant bacteria [ 17 ]. Furthermore, consumption of food contaminated by PMQR-positive strains or use of FQs in ambulatory and hospital therapy may promote pre-selection factors for FQ resistance [ 12 ].…”

“…Some studies have previously investigated the range of post-TRUS-Bx complications in the context of FQ resistance. Recently, our team published a study on the molecular mechanisms of FQ-resistance including the gyrA , gyrB and parC , parE mutations and PMQRs of Enterobacterales from rectal swabs of 48 men undergoing transrectal prostate biopsy [ 12 ]. Until recently, little has been known about the molecular properties of E. coli as causative agents of post-biopsy infections.…”