1. Characterization of quinolone resistance in Salmonella enterica serovar Typhimurium and its monophasic variants from food and patients in China
- Author
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Xiaojuan Yang, Shiyuan Yang, Shengrong Liu, Shuxiang Liu, Jumei Zhang, Weipeng Guo, Juan Wang, Zhongjian Song, Liang Xue, Moutong Chen, Shi Wu, Xianhu Wei, and Qingping Wu
- Subjects
Salmonella enterica serovar Typhimurium ,Salmonella enterica serovar 1,4,[5],12:i:- ,Quinolone resistance ,GyrA ,qnrS ,Microbiology ,QR1-502 - Abstract
ABSTRACT: Objectives: The study aimed to characterize the quinolone resistance of Salmonella enterica serovar Typhimurium and its monophasic variant (Salmonella enterica serovar 1,4,[5],12:i:-) isolated from food and patients in China. Methods: All of the isolates were assessed for quinolone susceptibility via the broth microdilution method. Then, the isolates were checked for mutations within quinolone resistance-determining regions of gyrA, gyrB, parC, and parE and were examined for plasmid-mediated quinolone resistance genes. Results: High rates of resistance to nalidixic acid in the S. Typhimurium (70.7%) and S. 1,4,[5],12:i:- (41.9%) isolates were observed, and a considerable proportion of isolates with reduced susceptibility to ciprofloxacin and levofloxacin were also detected. The high frequency of mutations in GyrA (60.8%) and a variety of genes (aac[6′]-Ib-cr [23.2%], oqxAB [19.2%], qnrS [13.6%], and qnrA [3.2%]) conferring quinolone resistance in these Salmonella isolates were noteworthy. Lastly, the isolates carrying qnrS for transferability and transmission of the quinolone resistance were analysed by conjugation. Multiple locus variable-number tandem repeat analysis profiles indicated that some qnrS-positive isolates were clonally related, whilst the other isolates were genetically divergent. This suggested that both clonal spread of resistant strains and horizontal transmission of the plasmid-mediated resistance genes contributed to the dissemination of qnrS-positive Salmonella isolates. Conclusion: This study highlights the prevalence of quinolone-resistant S. Typhimurium and S. 1,4,[5],12:i:- in China, posing a threat to public health.
- Published
- 2023
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