Molecular typing of Staphylococcus pseudintermedius isolates from clinically relevant cases of canine pyoderma

Staphylococcus pseudintermedius is a newly described species of Staphylococcus regarded as the main causative agent of canine pyoderma [1]; recently the first case of infection in humans was drescribed. An important characteristic of this pathogen is the high genetic identity with two other species of staphylococci, S. intermedius and S. delphini that all together are known as the Staphylococcus Intermedius Group (SIG) [2]. This scenario makes impossible a clear phenotypic differentiation of these three pathogens, but on the other hand, the genetic research kicks off the first molecular protocol for the identification of S. pseudintermedius [3]. The aim of this study was to investigate the presence of different biotypes of S. pseudintermedius coming from clinically relevant cases of pyoderma in dogs using three molecular methods commonly used for typing bacteria: the Ribosomal Spacers Amplification (RSA) [4], the Random Amplification of Polymorphic DNA (RAPD) [5] and the Restriction Fragment Length Polymorphism (RFLP) [6]. 46 different strains were included in this work. First of all it was performed the sequencing of all the strains in order to be sure on the presence of the interested species. The RSA technique was never applied before on this bacterium and in this work revealed a clear identification of the interested pathogen while it didn't highlight the presence of significative different biotypes. The RAPD assay showed a single cluster collecting all the interested strains, which are grouped in three different sub-clusters. The RFLP technique showed the most discriminative power, giving the opportunity to distinctly identify this bacterium. In conclusion, the use of these three different techniques allows clearly identifying S. pseudintermedius and observing the presence of different biotypes. In future could be interesting to couple these results with the determination of the antibiotic resistance patterns in order to verify if Multi Drug Resistant strains have particular RSA and RAPD profiles.