Profiles of Mutations and Plasmid-Mediated Quinolone Resistance Genes in Isolates with Different Levels of Fluoroquinolone Susceptibility.

PURPOSE

Fluoroquinolone-resistant is considered a serious public health problem and has been put on the WHO global priority list of antibiotic-resistant bacteria. This study was aimed to investigate the fluoroquinolone resistance in and its relevant genetic mechanisms.

MATERIALS AND METHODS

isolates that were isolated from diarrheal patient's feces in Ningbo China from 2011 to 2018 were tested for susceptibility to ampicillin, gentamicin, tetracycline, nalidixic acid, ciprofloxacin, and cefotaxime. Genes related to quinolone resistance were amplified by PCR.

RESULTS

A total of 118 isolates were collected, including 76 isolates, 40 isolates, and 2 isolates. Ciprofloxacin susceptibility test identified 10 (9%) susceptible, 65 (55%) intermediate, and 43 (36%) resistant isolates. Of 76 isolates, 37 were ciprofloxacin resistant, a prevalence significantly higher than 6 of 40 isolates (=0.01). The isolates collected during 2014-2018 displayed a significant increase in the prevalence of ciprofloxacin resistance (=0.05) than those collected during 2011-2013. All the ciprofloxacin-intermediate and resistant isolates had mutations of (S83L) and (S80I), whereas only the ciprofloxacin-resistant isolates had (D87N) mutation and gene. Additionally, 30% of the ciprofloxacin-resistant isolates were positive for gene.

CONCLUSION

This study shows the currently increasing prevalence of ciprofloxacin resistance. The reduced fluoroquinolone susceptibility is highly associated with (S83L) and (S80I) mutations, while the fluoroquinolone resistance is highly associated with (D87N) mutation, gene and perhaps gene.