Incidence and Characterization of Salmonella Isolates From Raw Meat Products Sold at Small Markets in Hubei Province, China

Min Zhou; Xiaofang Li; Wenfu Hou; Hongxun Wang; George C Paoli; Xianming Shi

doi:10.3389/fmicb.2019.02265

Incidence and Characterization of Salmonella Isolates From Raw Meat Products Sold at Small Markets in Hubei Province, China

Front Microbiol. 2019 Oct 4:10:2265. doi: 10.3389/fmicb.2019.02265. eCollection 2019.

Authors

Min Zhou¹, Xiaofang Li¹, Wenfu Hou¹, Hongxun Wang¹, George C Paoli², Xianming Shi³

Affiliations

¹ School of Food Science and Engineering, Wuhan Polytechnic University, Wuhan, China.
² Molecular Characterization of Foodborne Pathogens Research Unit, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center (USDA-ARS-ERRC), USDA-MOST Joint Research Center for Food Safety, Wyndmoor, PA, United States.
³ State Key Laboratory of Microbial Metabolism, School of Agriculture and Biology, MOST-USDA Joint Research Center for Food Safety, Shanghai Jiao Tong University, Shanghai, China.

Abstract

Salmonella is a leading cause of foodborne disease and is often associated with the consumption of foods of animal origin. In this study, sixty-six Salmonella isolates were obtained from 631 raw meat samples purchased at small retail suppliers in Hubei Province, China. The most prevalent Salmonella serotypes were Thompson (18.2%) and Agona (13.6%). Frequent antimicrobial resistance was observed for the sulfonamides (43.9%), tetracycline (43.9%), and the β-lactams amoxicillin and ampicillin (36.4% for each). Interestingly, a high incidence of resistance to cephazolin was observed in strains of the most common serotype, S. Thompson. Class I integrons were found in 27.3% (18/66) of the isolates and five of these integrons contained different gene cassettes (aacA4C-arr-3-dfr2, dfrA12-aadA21, aadA2, dfrA12-aadA2, dfr17-aadA5). Additional antimicrobial resistance genes, including bla _TEM-1, bla _CTX-M-65, bla _CTX-M-15, qnrB, and qnrS, were also identified among these Salmonella isolates. Results of replicon typing and conjugation experiments revealed that an integron with qnrB and bla _CTX-M-15 genes was present on incH12 mobile plasmid in S. Thompson strain. Multilocus sequence typing (MLST) analysis revealed 32 sequence types, indicating that these isolates were phenotypically and genetically diverse, among which ST26 (18.2%) and ST541 (12.1%) were the predominant sequence types. The integrons, along with multiple antimicrobial resistance genes on mobile plasmids, are likely contributors to the dissemination of multidrug resistance in Salmonella.

Keywords: MLST; Salmonella; blaCTX–M–15; blaCTX–M–65; class I integrons; qnrB.