Prevalence, antibiotic resistance, and virulence gene profiles of uropathogenic Escherichia coli (UPEC) isolated from raw milk: implications for public health

Raw milk, while nutritionally valuable, may act as a reservoir for zoonotic and antibiotic-resistant microorganisms, creating a potential pathway for foodborne urinary tract infections (FUTIs). Among foodborne pathogens, Escherichia coli stands out as both a commensal and a versatile pathogen responsible for approximately 80% of uncomplicated urinary tract infections (UTIs). Increasing evidence suggests that foodborne E. coli strains carrying uropathogenic traits can contribute to community-acquired UTIs, yet this link remains insufficiently characterized. This study provides a comprehensive assessment of the prevalence, antibiotic resistance, and virulence gene profiles of E. coli isolates obtained from raw milk samples collected in rural areas of Malatya province, Türkiye. A total of 206 bacterial colonies were isolated, and 115 were confirmed as E. coli through phenotypic and biochemical tests. Antibiotic susceptibility analysis revealed complete resistance to cephalothin and variable resistance to several antibiotics, yielding a Multiple Antibiotic Resistance (MAR) index of 0.178, indicative of moderate antibiotic selection pressure. Molecular identification via 16S rRNA sequencing confirmed 51 of 69 isolates (73.91%) as E. coli with ≥ 99% similarity. Screening for ten virulence genes demonstrated that 34 of the confirmed isolates (66.60%) carried three or more virulence determinants, classifying them as potential uropathogenic E. coli (UPEC). These findings demonstrate that raw milk can serve not only as a route for E. coli contamination but also as a reservoir of multidrug-resistant and uropathogenic strains. The coexistence of antibiotic resistance and UPEC-associated virulence factors in foodborne isolates provides novel evidence linking the food chain to the emergence of FUTIs. Continuous microbiological surveillance, antibiotic stewardship, and strict hygiene protocols throughout the dairy production chain are essential to prevent foodborne urinary tract infections and protect public health.