A Novel Method for Sampling and Long-Term Monitoring of Microbes That Uses Stickers of Plain Paper

Detection of pathogens is crucial in food production areas. While it is well established, swabbing as a state-of-the-art sampling method offers several drawbacks with respect to yield, standardization, overall handling, and long-term monitoring. This led us to develop and evaluate a method that is easier to use at a lower cost and that should be at least as sensitive. After evaluating sundry promising materials, we tested text-marking paper stickers for their suitability to take up and release Listeria monocytogenes with their nonsticky paper side over a 14-day time period using quantitative PCR. The recovery rate was similar to that in previous studies using conventional swabs, and we also confirmed the feasibility of pooling besides resilience to cleansing and disinfection. In a proof-of-concept experiment that sampled several locations, such as door handles, the occurrences of L. monocytogenes and Escherichia coli were determined. The results suggest that the presented sticker system might offer a promising cost-effective alternative sampling system with improved handling characteristics.IMPORTANCE As a ubiquitous bacterium, Listeria monocytogenes has a propensity to enter food production areas inadvertently via fomites such as door handles and switches. While the bacterium might not be in direct contact with the food products, knowing the microbial status of the surroundings is essential for risk assessment. Our investigation into a novel quantitative PCR (qPCR)-based sampling system with the highest sensitivity and ability to monitor over long periods of time, yet based on paper, proved to be cost-effective and reasonably convenient to handle.