Prevalence and antimicrobial resistance patterns of monophasic Salmonella typhimurium in Hanzhong, China

Yali Chen; Ning Zou; Yang Bai; Pengpeng Li; Shen Li; Yifei Han; Zhiqiang Zhang; Quanmin Ding; Jianjun Wei; Dongli Liu

doi:10.3855/jidc.21451

Prevalence and antimicrobial resistance patterns of monophasic Salmonella typhimurium in Hanzhong, China

Authors

Yali Chen Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Ning Zou Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Yang Bai Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Pengpeng Li Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Shen Li Institute of Pathogenic Microbiology, Shaanxi Provincial Center for Disease Control and Prevention, Xi’an 710054, P.R. China
Yifei Han Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Zhiqiang Zhang Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Quanmin Ding Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Jianjun Wei Hanzhong Center for Disease Control and Prevention, Hanzhong 723000, P.R. China
Dongli Liu Institute of Pathogenic Microbiology, Shaanxi Provincial Center for Disease Control and Prevention, Xi’an 710054, P.R. China https://orcid.org/0000-0002-3603-411X

DOI:

https://doi.org/10.3855/jidc.21451

Keywords:

Monophasic Salmonella typhimurium, whole-genome sequencing, antimicrobial resistance, cgMLST, cgSNP

Abstract

Introduction: Salmonella enterica, particularly the monophasic variant of Salmonella typhimurium, is a significant foodborne pathogen with an increasing prevalence and alarming multidrug resistance profile. This study analyzed the prevalence, antimicrobial resistance, and genomic characteristics of Salmonella typhimurium monophasic variants in Hanzhong, China.

Methodology: Genomic analysis was conducted on 94 Salmonella enterica strains derived from diarrheal patients in Hanzhong, China, from 2021 to 2023. Serotyping was performed using microbial mass spectrometry and whole-genome sequencing. Drug susceptibility testing was conducted. Drug resistance genes were screened. Genomic characterization included core genome multi-locus sequence typing (cgMLST) and core genome single-nucleotide polymorphism (cgSNP) analysis.

Results: Out of 94 strains, 34 were confirmed as monophasic Salmonella typhimurium. Notably, 85.29% of cases were in children under five years. Multi-drug resistance was alarmingly high at 88.24%, particularly against streptomycin (85.29%), tetracycline (70.59%), ampicillin (61.76%), and sulfamethoxazole (61.76%). Additionally, only one strain was fully susceptible to all tested antibiotics. Genomic analysis identified 30 distinct drug-resistance genes across the strains. All 34 strains belonged to the ST34 type. The cgMLST generated six clusters. The largest cluster contained 14 strains, predominantly from the Hantai District. The cgSNP analysis identified eight distinct evolutionary branches, each containing isolates from different periods and regions.

Conclusions: This study highlights the alarming prevalence and high resistance rates of monophasic Salmonella typhimurium in Hanzhong, particularly among vulnerable populations such as young children. The findings underline the urgent need for public health interventions, including enhanced monitoring and antibiotic stewardship, to mitigate the risks associated with this pathogen.

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Published

2025-11-30

How to Cite

Chen Y, Zou N, Bai Y, Li P, Li S, Han Y, Zhang Z, Ding Q, Wei J, Liu D (2025) Prevalence and antimicrobial resistance patterns of monophasic Salmonella typhimurium in Hanzhong, China. J Infect Dev Ctries 19:1664–1673. doi: 10.3855/jidc.21451

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Issue

Vol. 19 No. 11: November 2025

Section

Original Articles

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