Investigation of the prevalence of escherichia coli and uropathogenic escherichia coli (UPEC) virulence genes in raw milk samples

This study provides a comprehensive analysis of Escherichia coli strains isolated from 122 raw milk samples collected in the Malatya region, focusing on molecular identification, antibiotic resistance profiles, and the potential of Uropathogenic E. coli (UPEC). Initially, 206 colonies were isolated, with 115 biochemically confirmed as E. coli. Species-level confirmation using PCR amplification and sequencing of the 16S rRNA gene showed high similarity to E. coli. Antibiotic susceptibility tests revealed 100% resistance to cephalothin. Notable resistance rates were observed for fosfomycin (25.2%) and sulfametoksazol (8.7%). The Multiple Antibiotic Resistance (MAR) index was calculated as 0.178, indicating moderate antibiotic pressure contributing to resistance development. Additionally, 65.2% of isolates were identified as multidrug-resistant (MDR), exhibiting resistance to multiple antibiotic classes. For UPEC characterization, 69 isolates were screened for 10 virulence genes via PCR; fimA (98.5%) and agn43 (95.6%) were the most prevalent. Based on widely accepted criteria, 34 isolates (66.60%) carrying at least three virulence genes were classified as potential UPEC strains. This suggests that a significant portion of the E. coli isolates possess zoonotic and highly virulent pathotypes capable of causing urinary tract infections. In conclusion, raw milk products not only present a risk of microbiological contamination but also serve as reservoirs for antibiotic-resistant and UPEC-associated E. coli strains. These findings highlight the potential public health risks of raw milk consumption and underscore the need for stricter regulations and increased food safety awareness.