Droplet Digital PCR (ddPCR) Analysis for Detecting Shiga-Toxin-Producing Escherichia coli (STEC)

Abstract

Verocytotoxin-producing Escherichia coli, also referred to as Shiga-toxin-producing Escherichia coli (STEC), can be transmitted to humans through person-to-person contact, consumption of contaminated food or water, or by direct contact with animals. Its clinical and economic consequences have prompted the development of alternative approaches to the official method of analysis “UNI CEN ISO/TS 13136: 2012”, which describes the identification of STEC through the detection of its main virulence genes. Recently, droplet digital PCR (ddPCR) has been proposed as a technique for the sequence-specific detection and direct quantification of nucleic acids. The present study aimed to investigate if ddPCR could be able to detect STEC in less time than that required by the official method. This study consisted of the ddPCR of slices of beef contaminated with STEC and of the sponges used for beef official control at the slaughter stage. The results showed the ability of ddPCR to detect STEC in slices of beef already after sample incubation for 7 h at 37 °C while, in the case of sponges used for official controls, 9 h at 37 °C was needed. In this way, the ddPCR could represent an efficient method for detecting STEC and providing results in less time than the official method.