Molecular Characteristics And Susceptibility Pattern Of Sorbitol And Non-Sorbitol Fermenting Escherichia Coli Isolated From Unpasteurized Milk In Ohimini Lga

Abstract

Background and Aim:

Enterohaemorrhagic Escherichia coli O157:H7 is a non‑sorbitol‑fermenting serotype in unpasteurized milk, it is linked to severe hemorrhagic diarrhea. Unpasteurized milk sold by nomadic pastoralists who lack food‑safety training may amplify this risk. This study determined the prevalence, ESBL markers, and antibiotic susceptibility of non‑sorbitol‑fermenting E. coli O157:H7 in unpasteurized milk from Ohimini LGA in Benue State.

Materials and Methods:

100 milk samples were collected from four locations in Ohimin LGA. After enrichment and culture on selective agar, E. coli isolates were confirmed via morphology, biochemical, serological, and PCR. ESBL production was screened by double‑disk diffusion; blaSHV, blaTEM, and blaCTX‑M genes were detected by simplex PCR. Antibiotic susceptibility was assessed by Kirby–Bauer disk diffusion against aztreonam, imipenem, ceftazidime, augmentin, meropenem, cefepime, cefotaxime, ciprofloxacin, and gentamicin.

Results:

28% of samples yielded E. coli (57% non‑sorbitol fermenting, 43% sorbitol fermenting). Non‑sorbitol‑fermenting isolates exhibited 100% resistance to gentamicin; >93% to aztreonam and ceftazidime; 75% to augmentin; 62.5–65.2% to meropenem, cefepime, and cefotaxime; 57% to ciprofloxacin; and 6% to imipenem. They were most susceptible to imipenem (94%), with no susceptibility to gentamicin. All isolates were multidrug‑resistant; 100% of non‑sorbitol‑fermenting strains produced ESBLs carrying blaSHV, blaTEM, and blaCTX‑M.

Conclusion:

Virulent, multidrug‑resistant E. coli O157:H7 harboring ESBL genes is present in unpasteurized milk from Ohimini LGA. Mandatory pasteurization, stringent dairy hygiene, and stricter veterinary antibiotic regulations are urgently needed to protect public health.