Investigation of Shiga-like toxigenic Escherichia coli in meat products by quantitative PCR

Branko Velebit; Brankica Lakićević; Branka Borović; Vesna Janković; Danka Spirić; Tatjana Baltić

Branko Velebit Institute of meat hygiene and technology
Brankica Lakićević Institute of meat hygiene and technology
Branka Borović Institute of meat hygiene and technology
Vesna Janković Institute of meat hygiene and technology
Danka Spirić Institute of meat hygiene and technology
Tatjana Baltić Institute of meat hygiene and technology

Keywords: qPCR, E. coli O157, quantiﬁ cation

Abstract

The aim of this study was to investigate and evaluate effectiveness of quantitative PCR (qPCR) in quantiﬁ cation of Shiga-like toxigenic E. coli (STEC) in artiﬁ cially contaminated deli meat slices compared to plate count technique. Experiment was designed to investigate capability of qPCR using selected pair of primers amplifying rpoB household gene and serial decimal dilution of an overnight suspension of E. coli O157:H7 culture. Subsequently, slices of smoked pork loin were contaminated by respective decimally diluted dose of STEC. DNA was extracted from the samples and qPCR was run in triplicate. Mean Ct values of ampliﬁed rpoB gene were compared to each inoculum dose and standard curves were generated. Results clearly showed that the lowest detectable level of STEC in pork loin slices using qPCR was 6.8×10
CFU/g. Further optimization of method should be done in order to resolve, if possible, discrepancies at the levels of contamination less than 100 CFU/g.