Toxin profiling of Staphylococcus aureus strains involved in varicella superinfection

The most common complications of varicella are bacterial skin and soft tissue infections, generally due to Staphylococcus aureus and group A beta-hemolytic streptococci. The aim of this study was to characterize the toxin and antibiotic resistance profiles of S. aureus isolates involved in varicella complications. Between 2002 and 2007, the French Reference Centre for Staphylococci collected 58 S. aureus isolates involved in varicella superinfection. All the isolates were characterized by screening for 12 toxin genes, agr typing, and mecA gene detection; some isolates were also studied by spa typing, multilocus sequence typing (MLST), and resistance profiling. A major toxin gene was detected in 53% (31/58) of the isolates (genes for exfoliative toxins A and B, 17.2%; Panton-Valentine leukocidin gene, 8.6%; toxic shock syndrome toxin 1 gene, 27.6%). Most clinical manifestations were directly compatible with the classical activity of these toxins. Nineteen isolates (33%) were resistant to methicillin, and 12 of these isolates belonged to an emerging agr-2, ST5 clone that harbors the toxic shock syndrome toxin 1 gene. These data should be considered in the management and treatment of patients with varicella complicated by S. aureus superinfection. Antibiotics that decrease toxin production, such as clindamycin, may provide benefit, and their efficacy against bacterial superinfections in children with varicella should be studied.