Differentiation of mixed cultures of E. coli serovars from food samples on SMAC agar based on scatter pattern.

aLettuce and ground beef samples were inoculated with 102CFU/25g of each E. coli O26 and E. coli O157 cellsbE. coli colonies grown on SMAC agar for 10–11 h were matched with BARDOT library containing multiple standard strains of O157 STEC and non-O157 STEC.cE. coli serovar (O26 and O157) specific primers were used in multiplex PCR (mPCR). Prior to food sample analysis primers were validated for specificity with three standard strains of each E. coli O157:H7 and O26:H11. Primer sequences were adapted from reference [28].dIdentification accuracy measures the ratio of number of colonies correctly identified with BARDOT as well as PCR and total number of colonies analyzed. Identification of colonies with BARDOT and mPCR were performed as a blind study.eOne colony (#R1-3/C1) analyzed with mPCR did not produce any amplified products, however, it was identified as O157 serovar after analysis with BARDOT library.