High Prevalence of Virulence-Associated Genes and Length Polymorphism in and Genes Identified in Isolates from Meat Products and Meat-Processing Environments in Poland.

is a human pathogen that has the ability to cause listeriosis, a disease with possible fatal outcomes. The typical route of infection is ingestion of the bacteria with contaminated food. In this study, 13 virulence-associated genes were examined with PCR in the genomes of 153 isolates collected from meat products and processing environments in Poland. All isolates possessed genes from LIPI-1-, , , and -as well as four internalins: , , , . Invasion-associated protein , as well as genes and encoding regulatory proteins, were also detected in all isolates. Gene , encoding flagellin, was detected in 113 (74%) isolates. This was the only gene that was not detected in all isolates, as its presence is serotype-dependent. Gene showed polymorphism with longer and shorter variants in PCR amplicons. Two isolates were characterized by truncated genes, lacking 141 bp in their sequence, which was confirmed by gene sequencing. All isolates were positive in hemolysis assays, proving the synthesis of functional PrfA and Hly proteins. Four genotypes of based on polymorphism and two genotypes based on polymorphism were distinguished within the isolates' collection.