Multicenter study on the molecular characteristics of community-associated Methicillin-resistant Staphylococcus aureus in children with skin and soft tissue infection

Abstract

Objective To explore the molecular characteristics of community-associated Methicillin-resis-tant Staphylococcus aureus (CA-MRSA) from children with skin and soft tissue infection (SSTIs) in China. Methods CA-MRSA was collected from the outpatients in Department of Dermatology in 13 Children′s Hospitals of China.Genotypic characteristics of CA-MRSA isolates were tested by adopting multilocus sequence typing (MLST), staphylococcal protein A (spa) typing and Staphyloccoccal cassette chromosome mec (SCCmec) typing.And the presence of Panton-Valentine leukocidin genes(pvl) was determined also. Results Overall, 1 705 strains of Staphylococcus aureus were isolated from SSTIs children, and CA-MRSA accounted for 2.6% (44/1 705 strains). Two types of SCCmec were detected in all the CA-MRSA strains, and the main types were SCCmec Ⅳ and SCCmec Ⅴ, accounting for 45.5% (20/44 strains) and 54.5% (24/44 strains), respectively.Thirteen MLST types (STs) and 15 spa types were detected among CA-MRSA.The most prevalent MLST was ST121 (18/44 strains, 40.9%), followed by ST59 (9/44 strains, 20.5%). Additionally, t437 was predominant, accounting for 40.9% (18/44 strains). ST121 strain had 8 spa types, and t2086 was the most common type (6/18 strains, 33.3%); while ST59 had only 1 spa type, t437.No ST121, ST59 and t437 strains were found in Central and Eastern region of China.Only 4 (9.1%) of the 44 CA-MRSA strains harbored pvl genes which were all from Southern region. Conclusions The most common clone of SSTIs CA-MRSA in children is MRSA-ST121- SCCmec Ⅳ/Ⅴ, as the molecular epidemiology of CA-MRSA strain has changed, ST121 has replaced ST59 to become the main epidemic strains. Key words: Community-associated Methicillin-resistant Staphylococcus aureus; Skin and soft tissue infection; Molecular characteristics; Child; China