ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Food Microbiology
Molecular Detection, Serotyping, Cytotoxicity, and Antimicrobial Resistance of STEC and EPEC Isolated from Milk and Milk Products in Northern India
Provisionally accepted
- 1Rajiv Gandhi South Campus Banaras Hindu University, Banaras, India
- 2Govind Ballabh Pant University of Agriculture & Technology, Pantnagar, India
- 3Government Degree College Baramulla, Baramulla, India
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Shiga toxin-producing Escherichia coli (STEC) and Enteropathogenic E. coli (EPEC) are important foodborne pathogens posing significant public health threats. This cross-sectional study investigated the prevalence, virulence profiles, serotypes, cytotoxicity, and antimicrobial resistance profiles of STEC and EPEC from milk and milk products in Uttarakhand, Northern India. A total of 680 samples (260 raw milk and 420 milk product samples) were collected from dairy farms, milk shops, collection centres, and street vendors over nine months and screened for E. coli using conventional and molecular methods. Multiplex PCR targeting stx1, stx2, eaeA, and hlyA genes was employed to identify virulent isolates, which were further serotyped, evaluated for cytotoxicity on Vero cells, and tested for antibiotic susceptibility against 19 antibiotics. Resistant isolates were screened for tetA, tetB, sul1, and CITM genes by PCR. E. coli was detected in 28.82% of samples, with higher prevalence in raw milk (31.15%) than milk products (27.38%). Among isolates, 39.8% harbored at least one virulence gene, with stx1 being most prevalent. Serotyping revealed 22 O-serogroups, predominantly O18, O111, O120, O126, and O17. All stx-positive isolates showed cytopathic effects in Vero cells, enhanced after ciprofloxacin induction. High resistance was observed against ampicillin, tetracycline, oxytetracycline, cephalothin, and sulphonamides, while imipenem, gentamicin, and nalidixic acid were most effective. Among multidrug-resistant isolates, 95% carried tetB, sul1, or CITM genes, while tetA was absent. The study confirms the presence of virulent and multidrug-resistant STEC and EPEC in milk and dairy products, highlighting the need for improved hygiene, judicious antimicrobial use, and regular monitoring to mitigate food safety and zoonotic risks.
Keywords: antibiotic resistance, EPEC, Milk, Serotyping, STEC, Vero cell cytotoxicity, virulence genes
Received: 17 Nov 2025; Accepted: 29 Jan 2026.
Copyright: © 2026 Begum, Nigam and Mir. 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: Jubeda Begum
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