Identification of Antibiotic-Resistant Bacteria in Ready-to-Eat Salads Available in Supermarkets in Thalawathugoda Area, Sri Lanka

Abstract

The increasing demand for ready-to-eat (RTE) salads has raised concerns about food safety due to the potential for contamination by antibiotic-resistant bacteria. This study focused on the identification of antibiotic-resistant bacteria and their resistance profiles to discover resistant bacterial strains prevalent in RTE salads sold in supermarkets in Thalawathugoda area, Sri Lanka. To confirm the presence of pathogens, five different types of RTE salads were sampled and put through molecular analysis. These included Antibiotic Sensitivity Testing (ABST), DNA extraction, Polymerase Chain Reaction (PCR), Agarose gel electrophoresis, and Sanger sequencing. Antibiotic-resistant bacteria were found in S1 – Greek salad (GS),S3 – Potato salad (PS), S4 – Fresh Mix salad (FS), and S5 – Chicken potatoes and pineapple salad (CS), out of the five samples, according to the results. Amoxicillin displayed the strongest resistance in several samples, while ciprofloxacin was the most effective antibiotic according to ABST sensitivity patterns.Bacteria isolated from S2 - Apple salad (AS) showed sensitivity to each of the three tested antibiotics, suggesting that it is a high-quality sample with little chance of contamination by antibiotic resistant pathogenic bacteria. Staphylococcus spp. and Escherichia coli were detected in tested samples using PCR and agarose gel electrophoresis. Klebsiella quasipneumoniae was identified in S4 through Sanger sequencing,indicating the need for careful handling. The research highlights the significance of maintaining proper hygiene and implementing monitoring practices across the entire food supply chain, from production to retail, to minimize the risk of contamination in RTE salads. Further research and regular microbiological testing are recommended to ensure food safety and protect the health of customers.