Application of real-time PCR for detection of antibiotic resistant pathogens and Shiga-toxin producing Escherichia coli

Abstract

Salmonella and Shiga toxin producing Escherichia coli (STEC) are among the most important food pathogens. Increasing use of antibiotics for treatment and as a therapeutic agent on food animals has been proposed as a reason for the emergence of multiple drug resistant (MDR) strains of food pathogens. In this study real-time PCR methods were developed for the detection antibiotic resistant strains of Salmonella, extended-spectrum [beta]-lactam (ESBL) and carbapenem resistant pathogens. The United States Department of Agriculture Food Safety and Inspection Service (USDA-FSIS) declared seven STEC serogroups O157, O26, O45, O103, O111, O121 and O145 as adulterants in ground beef and beef trims. Multiplex real-time PCR melt curve assays with IAC were standardized for the detection of seven STEC serogroups with their virulence genes and Salmonella. The assay was able to detect all STEC strains in 325 g of ground beef and beef trims spiked with 10 CFU.