Quantitative and qualitative analysis of airborne Listeria monocytogenes on ready-to-eat meats

Bioaerosols are living organisms or substances from living organisms suspended in the air. They are responsible for allergies, sick building syndrome, and spread of bacterial and viral disease. Bioaerosols of food-production environments are of growing interest because of the potential for product contamination. Many studies have analyzed the air of meat and dairy production plants, while very few have focused on RTE foods. RTE foods are of concern because of the potential contamination with Listeria monocytogenes.;Listeria monocytogenes is a food borne pathogen, which is ubiquitous in the environment. L. monocytogenes is capable of survival and growth in many conditions meant to control bacteria. The unique growth characteristics combined with the ability for food contamination by a bioaerosol are a cause for concern. In addition to its unique survival abilities, this pathogen affects individuals with compromised or weakened immune system, such as pregnant women, the elderly and young. In these groups the high mortality rate of 20-40%.;The purpose of this work is to elucidate the problem of L. monocytogenes bioaerosols in food production and assess the risk of airborne L. monocytogenes to RTE meats in an experimental setting. To simulate an airborne-like condition L. monocytogenes attached to dry sterile sand and was dusted onto meat products. The RTE meat products were exposed at three levels (1.0, 5.0 and 10.0g). Half the samples were evaluated at day zero and the other half at day 28. All products were direct plated on chromogenic L. monocytogenes media, and then enriched in University of Vermont (UVM) broth and 4-Morpholinepropanesulfonic acid buffered Listeria enrichment broth (MOPS-BLEB). Following the enrichment the samples were evaluated for the presence of L. monocytogenes by plating onto Modified Oxford (MOX) media and with a commercially available Polymerase Chain Reaction (PCR) system. It was found the contamination of RTE meats by airborne L. monocytogenes is not dose dependent and cold storage had no effect on the risk. There was, however, a difference in the risk based on the RTE meat product type. These results are by not mean conclusive and more research is needed to better determine what is the true risk to RTE meats from L. monocytogenes bioaersosols and how the problem can be prevented or controlled during production.