PHENOTYPIC AND GENOTYPIC DETECTION OF COLISTIN RESISTANT ESCHERICHIA COLI FROM RAW BUFFALO MEAT IN PAKISTAN

Buffalo meat has been considered as a rich and essential source of proteins for human health. Colistin is considered as the last treatment choice for gram negative bacteria. In this era of modern medicine, the incidence of colistin-resistant Escherichia coli in food, especially meat, has emerged as a significant threat to human health. The present study is planned to detect multidrug resistant E. coli from raw buffalo meat with an emphasis on phenotypic and genotypic detection of colistin resistant E. coli. For this purpose, fresh and chilled raw buffalo meat samples (n=300) were collected and processed for characterization of E. coli. Kirby-Bauer method was used to detect MDR status of E. coli isolates. The colistin broth disc elution test was employed to detect colistin resistance phenotypically while polymerase chain reaction was used to find out genotypic colistin resistance targeting the mcr-1 and mcr-2 genes. The results of the survey conducted revealed that among the total samples collected, 36% (108/300) buffalo meat samples were found positive for E. coli. The highest antibiotic resistance was observed (100%) against tetracycline followed by cefotaxime, cefepime (97.2%) and ciprofloxacin (94.4%). In total, 99 E. coli isolates were detected multidrug resistant and among them 60 (60.60%) isolates were found colistin resistant. The mcr-1 gene was found in 44 (73.33%) colistin resistant isolates while none of the isolates was detected positive for mcr-2 gene. The existence of phenotypic colistin resistance and mcr-1 gene in E. coli isolates from raw buffalo meat is worrisome as this situation leaves us with no treatment options for gram negative pathogens leading the practitioners towards post-antibiotic era.