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ORIGINAL RESEARCH article

Front. Microbiol.
Sec. Antimicrobials, Resistance and Chemotherapy
Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1502138
This article is part of the Research Topic Global Dissemination and Evolution of Epidemic Multidrug-Resistant Gram-Negative Bacterial Pathogens: Surveillance, Diagnosis and Treatment, Volume III View all 10 articles

Phenotypic and WGS-derived antibiotic resistance patterns of Salmonella Enteritidis isolates from retail meat and environment during 2014 to 2019 in China

Provisionally accepted
Liya Zheng Liya Zheng 1Qiannan Di Qiannan Di 1Xuebin Xu Xuebin Xu 2Liyuan Liu Liyuan Liu 1Chunbo Qu Chunbo Qu 1Phil Bremer Phil Bremer 3*Xiujuan ZHOU Xiujuan ZHOU 1*
  • 1 Shanghai University of Medicine and Health Sciences, Shanghai, China
  • 2 Shanghai Municipal Center for Disease Control and Prevention (SCDC), Shanghai, China
  • 3 University of Otago, Dunedin, Otago, New Zealand

The final, formatted version of the article will be published soon.

    The emergence of multidrug-resistant (MDR) Salmonella Enteritidis has highlighted the importance of regularly monitoring for the occurrence of antibiotic-resistant strains. The current study combined phenotyping analysis and whole-genome-sequencing (WGS) to investigate the associations between the antibiotic-resistant phenotypes (ARPs) and genetic characteristics determinants in 95 Salmonella Enteritidis isolates from retail meat and environmental samples in China (2014-2019). Phenotypic analyses revealed that 70 isolates (73.68%) were MDR with 12 distinct resistance patterns. Most MDR strains (81.43%) had NAL-AMP-FIS-STR±TET profiles, showing a fluctuating trend from 2015 to 2019, likely influenced by tetracycline withdrawal management. WGS identified four types of mutations in the gyrA gene were associated with nalidixic acid resistance. The co-carrying of blaTEM, sul2 and aph(6)-Id/aph(3'')-Ib was likely mediated by an X1-type plasmid, corresponding to resistance against ampicillin, sulfisoxazole, and streptomycin. Combining phenotypic analyses and WGS data, the 31 sequenced strains were primarily divided into two clusters, with most epidemic resistant strains in the largest cluster A. Identical ARP patterns observed across different sample types, regions, and isolation years but clustering together in cluster A suggested potential cross-contamination within the retail chain. Cluster B exhibited more diverse resistance patterns and genetic characteristics. Notably, three isolates in cluster B require special mention: a monophasic strain resistant to eight antibiotics, a strain exhibiting highly heteroresistance, and a strain with additional exotoxin genes. These results highlight the importance of ongoing surveillance and the utility of WGS to track and understand antibiotic resistance in Salmonella Enteritidis.

    Keywords: Salmonella Enteritidis1, Whole-genome-sequencing2, Multidrug-resistant3, Clustering analysis4, Genetic determinants5

    Received: 26 Sep 2024; Accepted: 07 Jan 2025.

    Copyright: © 2025 Zheng, Di, Xu, Liu, Qu, Bremer and ZHOU. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Phil Bremer, University of Otago, Dunedin, 9016, Otago, New Zealand
    Xiujuan ZHOU, Shanghai University of Medicine and Health Sciences, Shanghai, China

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