Genotypic Diversity of Ciprofloxacin Nonsusceptibility and Its Relationship with Minimum Inhibitory Concentrations in Nontyphoidal <i>Salmonella</i> Clinical Isolates in Taiwan

• Main Authors: Shiuh-Bin Fang (Author), Tsai-Ling Yang Lauderdale (Author), Chih-Hung Huang (Author), Pei-Ru Chang (Author), Yuan-Hung Wang (Author), Katsumi Shigemura (Author), Ying-Hsiu Lin (Author), Wei-Chiao Chang (Author), Ke-Chuan Wang (Author), Tzu-Wen Huang (Author), Yu-Chu Chang (Author)
• Format: Book
• Published: MDPI AG, 2021-11-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

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 <i>Salmonella</i> (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 <i>gyrA</i>, <i>gyrB</i>, <i>parC</i>, and <i>parE</i>, and the 13 polymerase chain reactions for PMQR genes. We found that QRDR mutations were detected in <i>gyrA</i> (82.1%), <i>parC</i> (59.0%), and <i>parE</i> (20.5%) but not in <i>gyrB</i> among the 39 isolates. Five of the 13 PMQR genes were identified, including <i>oqxA</i> (28.2%), <i>oqxB</i> (28.2%), <i>qnrS</i> (18.0%), <i>aac</i>(6')-<i>Ib</i>-<i>cr</i> (10.3%), and <i>qnrB</i> (5.1%), which correlated with the MICs of CIP within 0.25-2 μg/mL, and it was found that <i>oxqAB</i> contributed more than <i>qnr</i> 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 (<i>p</i> < 0.001). Double mutations in <i>gyrA</i> and <i>parC</i> 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.

Item Description

10.3390/antibiotics10111383
2079-6382