Isolation and Genomic Analysis of a Case of Staphylococcus argenteus ST2250 Related to Sepsis in Italy

Staphylococcus argenteus, identified in 2006, represents a challenging case of bacterial taxonomic identification because of its high similarity to Staphylococcus aureus. In this context, neither mass spectrometry (MS) nor 16S gene analysis cannot precisely reveal the difference between the two species. In our study, the sensitivity to antibiotics of S. argenteus isolated from blood culture was tested, and the investigation of the bacterial genome was performed by Multi-Locus Sequence Typing (MLST) and Whole-Genome Next-Generation Sequencing (WG-NGS). The pathogen was identified as ST2250 and presented perfectly matched resistance genes, namely aph(3')-III, mgrA, and sepA, whereas the virulence gene detected was scn. Two plasmids were found: the pSAS plasmid, belonging to the family of Inc18, and plasmid pN315, belonging to the Rep3 group. The epidemiological distribution and the spread of S. argenteus infection are scarcely documented, particularly when associated with sepsis. Therefore, a correct taxonomy identification, antibiogram, and resistance gene analysis may help in acquiring knowledge about this bacterium and implement its detection and treatment.