Isolation and Molecular Characterization of Antimicrobial Resistant Escherichia coli from Healthy Broilers in Retail Chicken Outlets of Hotspot Cities in Southern India.

E. coli is one of the first commensal bacteria to colonize the chicken gut. It may act as a source for the spread of antibiotic resistance to human via the food chain and contamination of the environment. Isolation and characterization of such E. coli from commercial broilers in retail outlets of Southern India were carried out. Eighty-three E. coli isolates (76.9%) were obtained from cloacal/meat swabs (108 samples). Phenotypically, 78.3% of isolates were ESBL producers, 69.9% were fluoroquinolone-resistant, and 6% were carbapenemase producers. Genotypically, the blaSHV, blaTEM, and blaCTX-M were present in 48.2%, 43.4%, and 10.8% of the isolates, respectively. These isolates also carried fluoroquinolone-resistant genes viz qnrB (31.3%) and qnrS (34.9%) but not carbapenemase genes. Overall, ESBL were identified in 72.3% of isolates and fluoroquinolone-resistance genes in 51.8%. Strikingly, 53% of the isolates were multidrug-resistant, with both ESBL and fluoroquinolone-resistant genes. The study revealed the presence of MDR E. coli strains in broiler meat at retail outlets indicating the potential public health risks.