Emergence of MCR -1, -3, -6, -8 And -9) in Escherichia Coli Isolated from Live Chickens, Raw Chicken Meat and Vegetables from Kelantan, Malaysia

Abstract

The uncontrolled usage of antibiotics, especially colistin as growth promoter in poultry and the manures utilized as fertilizers in vegetable farming serve as the fundamental causes of mobilized colistin resistance (mcr) gene emergence in Escherichia coli (E. coli). This study was conducted to determine the prevalence, antibiotic susceptibility profile and phylogroups of colistin resistant E. coli isolated from poultry farm (217 chicken cloacal swab), 200 raw chicken meat and 100 vegetables samples from markets in Kelantan, Malaysia. The samples were processed using routine microbiological method, polymerase chain reaction (PCR) to detect colistin resistant E. coli isolates, disk diffusion antimicrobial susceptibility tests with 13 antibiotics, colistin minimum inhibitory concentration (MIC) test and PCR based phylogroups detection. The overall E. coli prevalence was 71.0% (367/517) and 3.9% (20/517) isolates harboured multiple mcr-genes (mcr-1, mcr-3, mcr-6, mcr-8 and mcr-9) from chicken origin only, while no mcr detected was in vegetables. The findings revealed that 89 – 100% E. coli isolates from chickens were resistant towards tetracycline, ampicillin, amoxicillin, and chloramphenicol with multiple antibiotic resistance index score of more than 0.2 yet the vegetable isolates were showing higher sensitivity towards these antibiotics. The ten mcr-harbouring isolates exhibited phenotypic colistin resistance at MIC ≥ 4 μg/ml. Meanwhile, phylogroup A (45.1%) and phylogroup B1 (20%) were predominating in chicken whereas phylogroup A (59.4%) was highlighted in vegetable origin isolates. These findings underscore the emerging threat of multidrug resistance and increasing trends of mcr in E. coli, mainly in food animals in Malaysia.