Melibiose–X-Gal–MacConkey Agar for Presumptive Differentiation of Escherichia albertii from E. coli and Salmonella from Poultry Meat

Abstract

The bacterial foodborne enteropathogen Escherichia albertii, despite enjoying increased attention paid to its pathogenesis, global dissemination, and antimicrobial resistance capacity, remains difficult to identify from human foods. The primary objective of this study was to develop and test a selective and differential plating medium for the isolation of E. albertii from enteric pathogens commonly transmitted via fresh poultry meat, namely E. coli and Salmonella enterica. MacConkey agar supplemented with α-D-+-melibiose and the lactose analogue X-gal was prepared and used to differentially enumerate E. albertii, Salmonella, and E. coli from inoculated ground chicken meat. The medium, MXgMac agar, differentiated the inoculated pathogens with a greater degree of efficiency than did the previously developed E. albertii-selective medium xylose–rhamnose–melibiose (XRM) MacConkey agar, based on differential usage of the lactose analogue and melibiose. Chicken-derived feces and litter samples were subsequently tested using the medium and found not to contain E. albertii by 16S rRNA gene amplification. MXgMac agar facilitates improved differential recovery of E. albertii and other enteric pathogens from poultry meat versus other E. albertii selective/differential media.