Antimicrobial susceptibility of Staphylococcus aureus isolated from children with impetigo in China from 2003 to 2007 shows community-associated methicillin-resistant Staphylococcus aureus to be uncommon and heterogeneous.

BACKGROUND: The number of patients with impetigo caused by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has been increasing.

OBJECTIVES: To investigate the antimicrobial susceptibility of S. aureus causing impetigo in children in China from 2003 to 2007 and further characterize isolates of CA-MRSA.

MATERIALS AND METHODS: We examined 984 S. aureus isolates for antimicrobial susceptibility to 11 antimicrobials using the agar dilution method. CA-MRSA isolates were analysed for Panton-Valentine leucocidin (PVL) genes, and staphylococcal cassette chromosome mec (SCCmec) typing was performed.

RESULTS: The largest proportion (94.5%) of strains were resistant to penicillin, followed by erythromycin (86.2%) and clindamycin (69.6%). In total 772 of 984 (78.5%) S. aureus strains were multiresistant. The incidence of CA-MRSA was 1.1%, with a high rate of resistance to clindamycin (90.9%) and tetracycline (72.7%), but all were susceptible to ciprofloxacin. The susceptibility profiles of MRSA to other antimicrobial agents were similar to those of methicillin-sensitive S. aureus (MSSA). None of the S. aureus strains were resistant to vancomycin and fusidic acid; moreover, only one strain was resistant to mupirocin. Typing of the SCCmec showed that 54.5% were type IV, 18.2% were type V and 9.1% were type VI. All the PVL-positive CA-MRSA carried SCCmec type IV.

CONCLUSIONS: CA-MRSA is still relatively uncommon and heterogeneous in children in China. Penicillin and erythromycin are no longer appropriate agents. Effective antibiotic agents for patients with impetigo are mupirocin and fusidic acid.