1. Wstęp. 2. Charakterystyka rodzaju Listeria. 2.1. Filogenetyczne pokrewieństwo pomiędzy gatunkami rodzaju Listeria. 2.2. Serotypy. 2.3. Geny charakterystyczne dla Listeria sp. 2.3.1. Mechanizmy wirulencji L. monocytogenes. 2.4. Chorobotwórczość L. monocytogenes. 3. Szczepy atypowe. 3.1. Szczepy atypowe wyizolowane z sera. 3.2. Atypowa niehemolityczna L. seeligeri. 3.3. Atypowa hemolityczna L. innocua. 3.4. L. marthii. 3.5. L. rocourtiae. 3.6. L. weihenstephanensis. 3.7. L. fleischmannii. 4. Podsumowanie

Abstract: The Listeria-like atypical strains have been identified in the natural environment and in the food samples lately. In recent times, Listeria monocytogenes isolates were characterized for molecular serogroup identification by multiplex PCR. Subsequently, virulence genes were detected. The results of the study show that the presence or absence of some virulence genes depends on the serotype of L. monocytogenes. The phylogenetic position and phenotypic character of isolated strains similar to Listeria spp. were studied. The atypical strains were examined based on diagnostic tests (hemolysis, CAMP, sugar fermentation, motility at 25°C) commonly used to identify Listeria. The isolates were highly similar phenotypically. The rrs gene sequence (encoding 16S rRNA) was analyzed in comparison to the genus Listeria. 16S rRNA sequencing data showed that these strains belong to the genus Listeria, but were different from all other known species. Phylogenetic distance from six known species of the genus Listeria indicated that they represent a novel species. The names Listeria marthii, Listeria rocourtiae, Listeria weihenstephanensis and Listeria fleischmannii were proposed for the four novel species isolated from samples obtained from the natural environment and food. Moreover, the presence of natural atypical hemolytic Listeria innocua strains and natural atypical nonhemolytic Listeria seeligeri isolates was observed. These strains differed from known L. innocua and L. seeligeri in only one of the hly gene.

1. Introduction. 2. Characterization of the genus Listeria. 2.1. Phylogenetic relation between species of the genus Listeria. 2.2. Serotypes. 2.3. The specific genes of the Listeria sp. 2.3.1. Mechanisms of virulence of L. monocytogenes. 2.4. Diseases associated with L. monocytogenes. 3. Atypical strains. 3.1. Atypical strains isolated from cheese. 3.2. Atypical nonhemolytic L. seeligeri strains. 3.3. Atypical hemolytic L. innocua strains. 3.4. L. marthii. 3.5. L. rocourtiae. 3.6. L. weihenstephanensis. 3.7. L. fleischmannii. 4. Summary