A new staphylococcal cassette chromosome mec IV encoding a novel cell-wall-anchored surface protein in a major ST8 community-acquired methicillin-resistant Staphylococcus aureus clone in Japan

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), which has staphylococcal cassette chromosome mec (SCCmec) type IV or V, has become a major concern worldwide. However, the involvement of SCCmecIV (or V) in community spread is still not fully understood. In this study, we searched for a possible adhesin gene in SCCmecIV, which could contribute to community colonization and spread. For this, we determined the entire SCCmecIV sequence of CA-MRSA in Japan, which was previously characterized as multilocus sequence type (ST) 8/SCCmecIVx (type IV with unknown subtypes). The SCCmecIV was 25,555 bp in size and flanked by 15-bp att sequences. The 8.2-kb J1 region was unique (through recombination) and contained a 4.8-kb orf (named spj), encoding for a novel 1,604-amino acid cell-wall-anchored surface protein (CWASP/J) with the LPXTG motif. The spj gene had no homology with any sequence submitted to GenBank, indicating a novel gene sequence. The new SCCmec IV was tentatively designated SCCmecIVl. A PCR assay specific to the spj gene was developed. Two steps of PCR for detection of the spj gene and SCCmecIV showed that ST8/SCCmecIVl MRSA is spreading widely in the community. This study demonstrates a new SCCmecIV encoding a novel CWASP, which could contribute to community spread as a potential colonization factor. Because ST8 CA-MRSA with SCCmecIVl causes skin and soft tissue infections and occasionally invasive infections, surveillance is needed.