Molecular Characterization of Multidrug-Resistant Escherichia coli Isolated from Beef and Chicken Meat Products in Samsun, Türkiye

Background: Foodborne pathogenic Escherichia coli is a major public health concern due to its frequent association with meat and meat products and its potential to harbor virulence factors and antimicrobial resistance (AMR) determinants. Objective: This study aimed to investigate the prevalence, virulence gene profiles, and AMR patterns of E. coli isolates obtained from beef and chicken meat products. Methods: A total of 200 beef and chicken meat product samples were collected from retail markets in Samsun, Türkiye. Isolation of E. coli was performed using conventional culture-based methods, and PCR targeting the uspA gene was used for molecular confirmation. The presence of virulence genes (stx1, stx2, eae, and hlyA) was investigated by PCR. Antimicrobial susceptibility testing was conducted using the disk diffusion method, and multidrug resistance (MDR) and multiple antibiotic resistance (MAR) indices were evaluated. Results: Among the 200 samples analyzed, 80 (40%) were positive for E. coli, including 38 (38%) beef and 42 (42%) chicken meat samples. A total of 185 E. coli isolates were recovered and confirmed by PCR. Virulence gene analysis showed that stx2 was the most prevalent gene (51.4%), followed by eae (37.3%), hlyA (13.0%), and stx1 (6.5%). Antimicrobial susceptibility testing demonstrated high resistance rates to tetracycline (69.7%), ampicillin (58.4%), trimethoprim–sulfamethoxazole (48.1%), streptomycin (40.5%), nalidixic acid (40.0%), chloramphenicol (40.0%), and ciprofloxacin (34.1%). In contrast, the lowest resistance rates were observed for imipenem (2.2%), amoxicillin–clavulanate (4.9%), and amikacin (7.6%). Moreover, 126 isolates (68.1%) were identified as MDR, exhibiting resistance to at least three antimicrobial agents. The MAR index ranged from 0.06 to 1.00. Conclusions: The coexistence of virulence-associated genes and high AMR rates among E. coli isolates from meat products indicates a potential public health risk. These findings highlight the importance of continuous monitoring of pathogenic and antimicrobial-resistant E. coli throughout the food production chain.