Prevalence of Multiple-Drug Resistance and Identification of Underlying Antibiotic Resistance Genes in Escherichia Coli Isolated from Ready-to-eat Chicken Salads Being Sold in Restaurants in Delhi, India

Antibiotic resistance (AR) is a quintessential one-health concern. Unregulated usage of antibiotics in human clinical and veterinary sector has exacerbated the global figures of morbidity and mortality. One of the reasons behind clinical manifestation of AR is the farm-to-fork movement of AR bacteria (ARB), which necessitates a systematic evaluation of food products for AR-related threats. Due to easier availability, claimed high nutritional value and cost effectiveness, meat-based ready-to-eat (RTE) salads are gaining popularity among the consumers in low-and middle-income countries (LMICs) like India. Nevertheless, it has not yet been followed by a stern microbial evaluation concerning AR. Our study acknowledges this gap by performing a systematic evaluation of AR profile of a sentinel opportunist, Escherichia coli associated with chicken based RTE salads being served in popular restaurants in Delhi, India; and identifying the antibiotic resistance genes (ARGs) that drive the observed resistance. Results showed a significant degree of resistance in E. coli isolates to nalidixic-acid (35.89%), tetracycline (35.0%), β-lactams [ampicillin (28.3%), amoxicillin-clavulanic acid (26%), imipenem (25%)], and fluoroquinolones [ciprofloxacin (22.5%), norfloxacin (20.83%)], among others. Upon screening the isolates for the presence of 22 ARGs, genes like qnrS (42.5%), tetA (40.83%), strB (20%), aadA1(12.5%), qnrA (12.5%) and strA (11.66%) were prevalent. Multiple drug resistance (MDR) was showcased by 29.17% isolates while multiple ARGs were harboured by 25.83% of the screened isolates. Due to the well-known association of the prevalent ARGs with plasmids and mobile genetic elements (MGEs) in our study, our results present a concerning scenario where the manifestation of AR in humans is possible through meat-based RTE salads.