High prevalence of multidrug-resistant extended spectrum beta lactamase -producing Escherichia coli in raw milk in Bangladesh

Raw milk is essential in our daily diet for food safety but poses a risk of contamination with harmful bacteria like ESBL Escherichia coli. The study was undertaken to characterize multidrug-resistant E. coli and determine the antibiogram profile of the isolates recovered from raw milk. A total of 80 raw milk samples were collected from 20 milk selling points in Sylhet and analyzed for physico-chemical parameters, microbial loads, ESBL Escherichia coli, and their virulent factors with the association of AMR. Results demonstrated that the mean specific gravity, fat%, protein%, lactose%, acidity%, SNF%, pH, and added water% were 1.026±0.0003, 3.83±0.072, 2.83±0.046, 4.08±0.080, 0.20±0.003, 7.47±0.144, 6.38±0.035, 1.72±0.034, respectively. The mean aerobic mesophilic count and mean coliform count were 〖2.72×10〗^7 CFU/ml and 1.53×〖10〗^6 CFU/ml respectively. We found the prevalence of E. coli was 60% (48/80) in raw milk, and PCR results revealed that all E. coli isolates positive for the stx1 (6.25%), eaeA (6.25%), blaCITM (8.33%), blaSHV (6.25%), blaTEM (14.58%), and tetA (50%) genes. The antibiogram results demonstrated that all the isolates were the most resistant to ampicillin and tetracycline (100%), amoxicillin (79.17%), ceftriaxone and ceftazidime (62.5%), streptomycin (58.53%) and gentamycin (60%), whereas vancomycin (79.17%), ciprofloxacin (75%) and meropenem (54.17%) were the most sensitive. Our study underscores the urgent need for stringent hygiene measures in milk production and emphasizes judicious antibiotic use in safeguarding public health.