Original Article Molecular characterization of community-acquired methicillin-resistant Staphylococcus aureus isolated from patients with skin and soft tissue infection in a teaching hospital

Staphylococcus aureus (S. aureus) particularly community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is the predominant cause of skin and soft tissue infections (SSTIs) worldwide. This study ex- amined the molecular characteristics and genotypes of CA-MRSA isolated from patients suffering from SSTIs. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were separated from secretions or pus of skin lesions of patients between 2008 and 2011 from Sun Yat-Sen Memorial Hospital. Identification of S. aureus isolates was performed by using a Vitek®2 microbial identification system. Genotypic analysis included pulsed-field gel electro - phoresis (PFGE), multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, and Panton-Valentine leukocidin (pvl) gene detection. Overall, 588 S. aureus from 516 patients were enrolled. 13 MRSA isolates (13/516, 2.5%) were CA-MRSA. The PFGE analysis grouped 13 isolates into two clusters (pulsotype A and B). Sequence type (ST) 239 was the most prevalent among the 6 observed STs, accounting for 46.2% (6/13, 46.2%), respectively. The other STs were ST59 (3/13), ST7 (1/13), ST338 (1/13), ST45 (1/13) and ST398 (1/13). SCCmec typing revealed that the common SCCmec type was type III (6/13) and type IV (5/13, including type IVa 2 isolates and type IVd 3 isolates). 53.8% (7/13) of isolates carried pvl gene. These data indicate ST239-SCCmec III and ST59-SCCmec IV was the most prevalent clone isolated from patients suffering from SSTIs. It suggested that hospital-acquired MRSA may be slowly spreading from hospital to community. We strongly advocate for more surveil- lance studies on MRSA in the community.