Antimicrobial resistant and multi drug resistant Salmonella and Escherichia coli from beef production chain and associated environments: A study in Kandy District, Sri Lanka

Consumption of meat contaminated with Salmonella and some of the pathotypes of Escherichia coli (E. coli) can lead to serious illnesses in humans and even death. Worsening the condition, emergence of antimicrobial resistance (AMR) in foodborne pathogens including Salmonella and E. coli have become a serious burden to public health. Little is known about the extent of AMR and Multidrug Resistant (MDR) prevailing in beef production chain and its associated environments in Sri Lanka. This study aimed to investigate the prevalence, AMR and MDR status of Salmonella and E. coli isolates from samples collected from cattle farms and beef stalls located in Kandy District. Overall, 44 samples of bovine manure, 40 samples of associated waste water were collected from cattle farms in five selected veterinary ranges. Nine raw beef samples with five associated wastewater samples were collected from beef stalls in one of the cities in Kandy District. Isolation and identification of Salmonella and E. coli, and the detection of their AMR and MDR were done using standard and recommended methods including polymerase chain reaction. Presence of Salmonella and E. coli in manure was 4.55% and 79.55%, respectively. Among the beef samples tested, 88.89% were contaminated with Salmonella and 44.44% were contaminated with E. coli. The isolation rates of Salmonella and E. coli from waste water were 15.0% and 62.5% respectively. The analyses revealed that the presence of Salmonella in beef was relatively higher than its presence in manure and wastewater. All the Salmonella and E. coli isolates were resistant to erythromycin. Additionally, 100% susceptibility was observed for chloramphenicol and gentamicin. About 5.71%, 16.0%, and 75.0% of E. coli isolates from bovine manure, farm wastewater, and beef samples, respectively, were MDRs with resistance to >/=3 classes of antimicrobials. No MDR Salmonella isolates were detected. The low levels of Salmonella in manure but its high prevalence in beef indicated harvest to post-harvest contaminations during beef production chain where control measures need to be implemented. The study alarms the necessity of investing the risks of food-borne pathogens, AMR and MDR in one of the underexplored research areas in the country: beef industry.