BT 1A Genetic group 1 comprised of isolates with related 16S rRNA gene sequences but with great variation in their pathogenicity-associated properties. On the contrary, BT 1A Genetic group 2 was found to be rather uniform and phylogenetically distinct from the other Y. enterocolitica BT 1A strains. The genetic similarity of this group to Genetic group 1 was 95–96% based on the MLST sequences and 98–99% based on the 16S rRNA gene sequences. All the 17 strains determined to belong to Y. enterocolitica https://www.selleckchem.com/products/KU-60019.html BT 1A Genetic group 2 were ystB negative in PCR and were resistant to the five tested yersiniophages. Additionally, none of

them fermented fucose, as determined in our previous study [27]. Decitabine in vivo Likewise, pathogenic pYV + yersinia strains do not ferment fucose, whilst 91% of the BT 1A strains other than those of Genetic group 2 do. Of the Genetic group 2 strains 82% were resistant to serum complement killing and 76% belonged to LPS type A2. Remarkably, the 16S rRNA sequences of BT 1A Genetic group 2 were more similar to Y. intermedia, Y. mollaretii, Y.

aldovae and Y. bercovieri than to Y. enterocolitica 16S rRNA sequences. However, a previous study indicated that the use of MLST of house-keeping genes determined genetic relatedness among Yersiniae better than 16S rRNA [29]. Studies using both DNA hybridization and 16S rRNA gene sequence data have illustrated that if two strains show less than 97% 16S rRNA gene sequence similarity, they are separate species [30]. Nevertheless, even 99% similarity of 16S rRNA genes does not guarantee that bacterial strains represent the same species. Howard and colleagues [17] have already suggested that BT 1A strains should be designated as a third subspecies of Y. enterocolitica based on the comparison of whole genomes using DNA microarray. It is likely that the genetic difference between the two phylogenetic groups of Y. enterocolitica BT 1A discovered in the present study may also

be high enough to justify designation of different subspecies or even species. Although further analyses would be needed for species designation, our data add insight into the phylogeny of the genus Yersinia, which is continuously evolving: three novel Yersinia Cytidine deaminase species, Y. entomophaga, Y. pekkanenii and Y. nurmii were described as recently as 2010 [31–33]. This is the first time that two phylogenetic clusters of Y. enterocolitica BT 1A strains are reported based on the sequence analysis of house-keeping genes, but similar results indicating the existence of two main clusters of BT 1A strains have been obtained with other molecular methods, such as ribotyping and REP-ERIC [21], gyrB-RFLP [22], AFPL [16], MLEE [23, 24] and, most recently, MALDI-TOF mass spectrometry to identify the protein mass patterns [25].