Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission

Jilin province is the primary region for dairy cow and milk production in China. However, there are few reports on the genetic characteristics, antibiotic resistance, and prevalence of Staphylococcus aureus (S. aureus) in raw milk. Between 2021 and 2022, researchers identified 214 S. aureus strains,...

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Main Authors: Qianhong Liu, Pengming Ma, Qiaoyi Gu, Wen Yang, Chunhua Li
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Microbiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fmicb.2025.1547283/full
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author Qianhong Liu
Qianhong Liu
Pengming Ma
Qiaoyi Gu
Wen Yang
Chunhua Li
author_facet Qianhong Liu
Qianhong Liu
Pengming Ma
Qiaoyi Gu
Wen Yang
Chunhua Li
author_sort Qianhong Liu
collection DOAJ
description Jilin province is the primary region for dairy cow and milk production in China. However, there are few reports on the genetic characteristics, antibiotic resistance, and prevalence of Staphylococcus aureus (S. aureus) in raw milk. Between 2021 and 2022, researchers identified 214 S. aureus strains, with a prevalence rate of 42.8% in cattle farms across Jilin province. Among the 214 strains, 22 isolates of methicillin-resistant Staphylococcus aureus (MRSA) were identified, with 13 exhibiting prevalent antibiotic resistance. Penicillin exhibited the highest resistance rate (145/214, 67.76%). The profiles of drug resistance, pathogenicity, genetic traits, and biofilm formation were examined through whole genome sequencing (WGS) of 44 isolates, comprising 22 MRSA strains and 22 methicillin-sensitive Staphylococcus aureus (MSSA) strains. Of the 44 isolates, 25 (56.82%) exhibited multiple resistance, while 31 (70.45%) demonstrated drug resistance characteristics. We identified 12 distinct types of drug resistance genes, including those associated with tetracycline, quaternary ammonium salt disinfection, and β-lactam. Six strains were found to carry genes conferring resistance to linezolid. The Aur and hlgA/B/C virulence genes were identified in at least 90% of the strains, with ST9-t899 emerging as the predominant type. Human–livestock transmission may be present, as indicated by the single-nucleotide polymorphism (SNP) and WGS data. The isolates also exhibited increased resistance. Moreover, strong biofilm formation was observed among the MRSA strains compared to the MSSA strains. The isolates exhibited multi-drug resistance, a broad spectrum of drug resistance, and various drug resistance phenotypes. CC398 and CC9 demonstrated potential for human-to-livestock transmission, as evidenced by the identification of 22 CC9 and 15 CC15 strains among the 44 isolates. OptrA, cfrA, and poxtA genes were identified in five, seven, and one strains, respectively, indicating contamination within the population. Given that raw milk is a fundamental food source, it is essential to monitor the molecular characteristics and antimicrobial resistance (AMR) of S. aureus to ensure food safety and hygiene. From a One Health perspective, controlling antimicrobial resistance (AMR) is crucial as it can be transmitted from food-producing animals to humans, thus impacting public health.
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spelling doaj-art-7358b71f1dcf4aee9fede900e13f8f232025-08-20T03:12:54ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-05-011610.3389/fmicb.2025.15472831547283Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmissionQianhong Liu0Qianhong Liu1Pengming Ma2Qiaoyi Gu3Wen Yang4Chunhua Li5College of Animal Science, Xichang University, Xichang, ChinaKey Laboratory of Animal Epidemic Disease Detection and Prevention in Panxi District, Sichuan, ChinaXichang Agriculture and Rural Bureau, Xichang, ChinaCollege of Animal Science, Xichang University, Xichang, ChinaCollege of Animal Science, Xichang University, Xichang, ChinaCollege of Animal Science and Technology, Jilin Agricultural Science and Technology University, Jilin, ChinaJilin province is the primary region for dairy cow and milk production in China. However, there are few reports on the genetic characteristics, antibiotic resistance, and prevalence of Staphylococcus aureus (S. aureus) in raw milk. Between 2021 and 2022, researchers identified 214 S. aureus strains, with a prevalence rate of 42.8% in cattle farms across Jilin province. Among the 214 strains, 22 isolates of methicillin-resistant Staphylococcus aureus (MRSA) were identified, with 13 exhibiting prevalent antibiotic resistance. Penicillin exhibited the highest resistance rate (145/214, 67.76%). The profiles of drug resistance, pathogenicity, genetic traits, and biofilm formation were examined through whole genome sequencing (WGS) of 44 isolates, comprising 22 MRSA strains and 22 methicillin-sensitive Staphylococcus aureus (MSSA) strains. Of the 44 isolates, 25 (56.82%) exhibited multiple resistance, while 31 (70.45%) demonstrated drug resistance characteristics. We identified 12 distinct types of drug resistance genes, including those associated with tetracycline, quaternary ammonium salt disinfection, and β-lactam. Six strains were found to carry genes conferring resistance to linezolid. The Aur and hlgA/B/C virulence genes were identified in at least 90% of the strains, with ST9-t899 emerging as the predominant type. Human–livestock transmission may be present, as indicated by the single-nucleotide polymorphism (SNP) and WGS data. The isolates also exhibited increased resistance. Moreover, strong biofilm formation was observed among the MRSA strains compared to the MSSA strains. The isolates exhibited multi-drug resistance, a broad spectrum of drug resistance, and various drug resistance phenotypes. CC398 and CC9 demonstrated potential for human-to-livestock transmission, as evidenced by the identification of 22 CC9 and 15 CC15 strains among the 44 isolates. OptrA, cfrA, and poxtA genes were identified in five, seven, and one strains, respectively, indicating contamination within the population. Given that raw milk is a fundamental food source, it is essential to monitor the molecular characteristics and antimicrobial resistance (AMR) of S. aureus to ensure food safety and hygiene. From a One Health perspective, controlling antimicrobial resistance (AMR) is crucial as it can be transmitted from food-producing animals to humans, thus impacting public health.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1547283/fullraw milkStaphylococcus aureusMRSAdrug resistancegenetic characteristicswhole genome sequencing
spellingShingle Qianhong Liu
Qianhong Liu
Pengming Ma
Qiaoyi Gu
Wen Yang
Chunhua Li
Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
Frontiers in Microbiology
raw milk
Staphylococcus aureus
MRSA
drug resistance
genetic characteristics
whole genome sequencing
title Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
title_full Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
title_fullStr Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
title_full_unstemmed Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
title_short Genomic epidemiology and characterization of Staphylococcus aureus isolates from raw milk in Jilin, China: evidence of contamination with optrA-positive, cfrA-positive, and poxtA-positive strains and human–livestock transmission
title_sort genomic epidemiology and characterization of staphylococcus aureus isolates from raw milk in jilin china evidence of contamination with optra positive cfra positive and poxta positive strains and human livestock transmission
topic raw milk
Staphylococcus aureus
MRSA
drug resistance
genetic characteristics
whole genome sequencing
url https://www.frontiersin.org/articles/10.3389/fmicb.2025.1547283/full
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