Unusual carriage of virulence genes sasX/sesI/shsA by nosocomial Staphylococcus haemolyticus from Brazil.

Background: Staphylococcus haemolyticus is an emerging threat in the nosocomial environment but only some virulence factors are known. Materials & methods: The frequency of the sasX gene (or orthologues sesI/shsA), encoding an invasiveness-related surface-associated protein, in S. haemolyticus was detected in different hospitals in Rio de Janeiro. Results: 9.4% of strains were sasX/sesI/shsA-positive, some were in the context of the ΦSPß-like prophage and devoid of CRISPR systems, indicating potential transferability of their virulence genes. Gene sequencing evidenced that Brazilian S. haemolyticus harbored sesI, instead of the usual sasX, while S. epidermidis had sasX instead of sesI, suggesting horizontal acquisition. Conclusion: The contexts of Brazilian sasX/sesI/shsA favor transfer, which is alarming given the difficulty in treating infections caused by S. haemolyticus.