Among the four lineages described for Listeria monocytogenes (I, II, III, and IV), lineages I and II harbor the serotypes most closely related to listeriosis in humans. Serotypes 1/2b and 4b are associated with the majority of listeriosis outbreaks, and serotype 1/2a is frequently involved in food and processing plant contamination. As such, the present study utilizes phylogenetic analysis for the aim of determining genomic differences between two L. monocytogenes strains isolated in southern Brazil (serotypes 1/2a and 4b) and known reference strains (L. monocytogenes EGD-e and L. monocytogenes Scott A). The Illumina Miseq platform was used to perform genomic sequencing, and cluster analysis of orthologous groups facilitated the investigation of similarities and differences between the two serotypes studied. In line with previous research, the studied strains of serotypes 1/2a and 4b presented different proteins related to resistance and virulence that may represent adaptations to several conditions during its evolution
