Comparison of In-house and Commercial Real-time PCR Systems for the Detection of Enterobacteriaceae and their Evaluation Within an Interlaboratory Study Using Infant Formula Samples

Traditional detection methods for Enterobacteriaceae in foods are time-consuming and laborious. The current study assessed the specificity of three real-time PCR primer sets. Set A (IEC primers) targeted the conserved flanking regions of the 16S rRNA, the 16SITS-23S gene region. Set B (ENT primers) annealed to Escherichia coli 16S ribosomal RNA gene. The third set (C) used a D-LUXTM (Light Upon eXtension) single FAMlabelled forward primer and a corresponding unlabeled primer. Set A was specific for E. coli and for some nonEnterobacteriaceae. SYBR Green-based real-time PCR confirmed the specificity of set B for the Enterobacteriaceae but also detected Vibrionaceae. In contrast, set C was poorly specific. However, set D including the forward LUXTM primer from set C and the reverse primer from set B had a specificity comparable to that of set B, but with higher sensitivity. This combined set was successfully applied to detect Enterobacteriaceae in infant milk formula and compared favourably with a commercial real-time PCR kit.