Implementation of the DEP-pooling approach for L. monocytogenes detection over 25-months by two diagnostic laboratories of an Austrian dairy company

Abstract

Diagnostic strategies to detect foodborne pathogens such as L. monocytogenes in food processing environments are cost- and time-consuming necessities to ensure safe food. In this study we present in-house monitoring data of a relatively novel direct enrichment PCR (DEP) pooling approach for the detection of L. monocytogenes in the food industry. The DEP-pooling approach was initially developed and reported by our working group in 2017 and has since been implemented as the routine L. monocytogenes diagnostic method by an Austrian dairy producer in two of its internal diagnostic laboratories. The results of almost 50,000 individual routine samples demonstrate the overall applicability, reliability and cost-saving capability of the DEP-pooling approach. While the original DEP-pooling approach was designed and evaluated as a qualitative test, the quantitative PCR results of 168 positive samples show that a separation between samples that contained culturable or non-culturable L. monocytogenes is possible. In conclusion, the present study demonstrates the advantages of a straightforward combination of microbiological and molecular biological methods in a routine setup. It is not only cost- and time-efficient, but can also potentially identify the source of recurring contamination via non-culturable cells. These results should encourage researchers, biomedical companies and industrial customers alike to implement such new cost-efficient methods to ensure a safe food production environment.