Genotypic diversity of ciprofloxacin nonsusceptibility and its relationship with minimum inhibitory concentrations in nontyphoidal salmonella clinical isolates in taiwan

Shiuh Bin Fang*, Tsai Ling Yang Lauderdale, Chih Hung Huang, Pei Ru Chang, Yuan Hung Wang, Katsumi Shigemura, Ying Hsiu Lin, Wei Chiao Chang, Ke Chuan Wang, Tzu Wen Huang, Yu Chu Chang

*Corresponding author for this work

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Abstract

This study analyzed the genetic diversity of ciprofloxacin (CIP) nonsusceptibility and the relationship between two major mechanisms and minimum inhibitory concentrations (MICs) of CIP in nontyphoidal Salmonella (NTS). Chromosomal mutations in quinolone resistance-determining regions (QRDRs) and plasmid-mediated quinolone resistance (PMQR) genes were searched from ResFinder, ARG-ANNOT, and PubMed for designing the sequencing regions in gyrA, gyrB, parC, and parE, and the 13 polymerase chain reactions for PMQR genes. We found that QRDR mutations were detected in gyrA (82.1%), parC (59.0%), and parE (20.5%) but not in gyrB among the 39 isolates. Five of the 13 PMQR genes were identified, including oqxA (28.2%), oqxB (28.2%), qnrS (18.0%), aac(6 )-Ib-cr (10.3%), and qnrB (5.1%), which correlated with the MICs of CIP within 0.25–2 µg/mL, and it was found that oxqAB contributed more than qnr genes to increase the MICs. All the isolates contained either QRDR mutations (53.8%), PMQR genes (15.4%), or both (30.8%). QRDR mutations (84.6%) were more commonly detected than PMQR genes (46.2%). QRDR mutation numbers were significantly associated with MICs (p < 0.001). Double mutations in gyrA and parC determined high CIP resistance (MICs ≥ 4 µg/mL). PMQR genes contributed to intermediate to low CIP resistance (MICs 0.25–2 µg/mL), thus providing insights into mechanisms underlying CIP resistance.

Original languageEnglish
Article number1383
JournalAntibiotics
Volume10
Issue number11
Number of pages14
ISSN2079-6382
DOIs
Publication statusPublished - 2021

Keywords

  • Ciprofloxacin nonsusceptibility
  • Minimum inhibitory concentrations
  • Nontyphoidal Salmonella
  • Plasmid-mediated quinolone resistance
  • Quinolone resistance determining regions

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