DRP004655
Identification and detection of USA300 methicillin-resistant Staphylococcus aureus clones with a partial deletion in the ccrB2 gene on the type IV SCCmec element
The staphylococcal cassette chromosome (SCC) mec typing is important method used to rapidly screen USA300 clones, which are highly pathogenetic methicillin-resistant Staphylococcus aureus (MRSA). Here, we report USA300-like strains (named as pseudo USA300), which could not be identified as SCCmec type IV by the conventional PCR method. Among the 82 USA300 strains, 23.2% (19 isolates) failed to identify as SCCmec type IV. Genome analysis revealed that the pseudo USA300 has a 12 bp deletion at the primer binding site of ccrB2, located on the SCCmec element. We developed a new primer and could accurately identify the SCCmec type of all USA300 and pseudo USA300 strains. Our findings showed that at least 20% of the USA300 clones have a partially defective ccrB2 gene. The new primer designed in this study is useful for screening USA300 clones.