Molecular characterisation of gyrA, parC and qepA genes in quinolone resistance extended spectrum beta-lactamase producing escherichia coli isolates in HTAA, Kuantan

Abstract

Quinolone resistance (QR) and extended-spectrum β-lactamase (ESBL) production have increased in Escherichia coli and considered a serious problem worldwide. It is worth to monitor the resistance mechanism in E. coli to provide guidance for optimising antimicrobial treatments and control the spread of resistance. The objective of this study was to molecularly characterize gyrA, parC and plasmid-mediated qepA efflux pump genes, in QR-ESBL E. coli isolates obtained from patients in HTAA, Kuantan. The antibiotic susceptibility profile was also studied. 32 QR-ESBL and six quinolone-susceptible E. coli isolates from (September to December 2018) were included in the study. The isolates were reconfirmed with known phenotypic tests. The antibiotic susceptibility test was performed according to CLSI, 2019 guidelines. PCR and DNA sequencing were performed for the identification of mutations in quinolone resistance determining region (QRDR) of gyrA and parC genes. Resistance to ampicillin, tetracycline, nalidixic acid was (100%) followed by cefotaxime (96.9%), ciprofloxacin (78.1%) trimethoprim-sulfamethoxazole (75%), ceftazidime (56.3%), cefepime (43.8%) and gentamycin (25%). None of the isolates was resistant to piperacillin-tazobactam, amikacin, imipenem, meropenem, ertapenem, and colistin. PCR successfully amplified the gyrA and parC genes. However, qepA gene was not detected by PCR in the isolates. The majority of the isolates had a point mutation in QRDR of gyrA at codons 83 and 87 and in parC at codons 80 and 84. Two isolates had mutations outside of QRDR at codons 144 and 167 in parC. A strong positive correlation was found between MIC levels of ciprofloxacin and the number of resistance mutations. The sequencing of 6QS-ESBL E. coli revealed the absence of resistance mutations. Quinolone resistance in the isolates was mainly due to mutations in gyrA, parC genes. Acquisition of multidrug resistance (MDR) genes through innate gene mutations and mobile genetic elements contributed to the emergence of MDR. This study reinforces the importance of being vigilant in utilising molecular techniques to monitor the emergence of resistance genes in different locations.