Posted on the Pediatric SuperSite on October 5, 2009
PVL linked with heightened S. aureus disease severity in children
Children with staphylococcal scarlet fever caused by
Panton-Valentine leukocidin–positive Staphylococcus aureus strains
had more exacerbated skin manifestations and greater systemic inflammatory
responses compared with children who had strains that were negative for the
cytotoxin.
“Clinical improvement after incision and drainage
was achieved for most children with staphylococcal scarlet fever caused by
Panton-Valentine leukocidin (PVL)–positive methicillin-resistant S.
aureus strains, despite treatment with an ineffective antibiotic,”
wrote the researchers from the Tri-Service General Hospital at the National
Defense Medical Center in Taipei, Taiwan.
This is the first study conducted to prospectively
compare children with staphylococcal scarlet fever with and without the
presence of PVL, according to the researchers.
The researchers compared clinical characteristics and
lab findings among 49 children who were treated for staphylococcal scarlet
fever caused by community-associated S. aureus isolates during an
11-year study period and used multivariate analysis to determine the following:
- 26 children had a methicillin-susceptible S. aureus isolate;
23 had a methicillin-resistant isolate.
- 24 isolates, including five MSSA and 19 MRSA, were positive for PVL;
25 isolates (21 MSSA, 4 MRSA) were negative for PVL.
- Children with PVL–positive isolates had significantly larger
abscess sizes; higher white blood cell counts; higher C-reactive protein
levels; and longer durations of fever, generalized scarlatiniform rashes and
hospital stays.
- Among the 19 PVL–positive MRSA isolates, 17 carried the
staphylococcal cassette chromosome mec VT and all were
multilocus sequence type 59.
- Staphylococcus enterotoxin B was most common, with 92% of all
isolates (23 MSSA, 22 MRSA) containing only that toxin.
Despite initiating antibiotic therapy within 24 hours of
hospital admission for all patients, initial antibiotics were effective in only
53% of the patients; however, the researchers noted no significant association
between ineffective antimicrobial therapy and clinical outcome.
Lo W-T. Clin Infect Dis. 2009;49:e69-e75.
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