Molecular Characterization and Antimicrobial Susceptibility Pattern of Sorbitol and Non-Sorbitol Fermenting Escherichia Coli Isolated from Unpasteurized Milk in Ohimini LGA, Benue State, Nigeria

Background: The presence of pathogenic Escherichia coli in unpasteurized milk increases the risk of infection. This study investigated the prevalence, extended-spectrum beta-lactamase (ESBL) indicators, and antibiotic susceptibility pattern of pathogenic E. coli in unpasteurized milk in Ohimini Local Government Area (LGA) of Benue State.Materials & Methods: In this study, ۱۰۰ milk samples were collected from Ohimini LGA, and E. coli isolates were identified through various methods including morphological, biochemical, serological, and PCR (polymerase chain reaction) tests. ESBL production was screened using the double-disc diffusion method, and β-lactamase genes (blaTEM, blaSHV, blaCTX-M) were detected through simplex PCR. Antibiotic susceptibility was assessed against multiple antibiotics using the Kirby–Bauer disc diffusion method.Findings: About ۱۳% of the samples tested positive for E. coli, with four (۳۰.۸%) and nine (۶۹.۲%) cases classified as non-sorbitol fermenting (NSF) and sorbitol fermenting (SF) isolates, respectively. All isolates were resistant to gentamicin. SF isolates showed significant resistance to ceftazidime (n=۶, ۶۶.۷%), aztreonam (n=۴, ۴۴.۴%), ciprofloxacin (n =۴, ۴۴.۴) and amoxicillin–clavulanate (n=۴, ۴۴.۴%) but were less resistant to imipenem (n=۱, ۱۱%) and other β-lactams. In contrast, NSF isolates exhibited higher resistance rates across multiple agents, with three (۷۵%) isolates showing resistance to aztreonam, ceftazidime, amoxicillin-clavulanate, cefotaxime, and two (۵۰%) isolates showing resistance to cefepime, ciprofloxacin, and meropenem. All NSF isolates were multidrug-resistant and tested positive for at least one ESBL gene (blaTEM, blaSHV, or blaCTX-M) when analyzed via PCR.Conclusion: Multidrug-resistant E. coli with ESBL genes detected in unpasteurized milk samples in Ohimini LGA emphasizes the necessity of mandatory pasteurization, enhanced dairy hygiene, and stricter veterinary antibiotic regulations to protect public health.

کلیدواژه ها:

Escherichia coli ، Milk ، Antimicrobial Susceptibility Tests ، Drug Resistance ، Bacterial ، Beta-lactamases ، Polymerase Chain Reaction