Association between lesional or non lesional S. aureus strains from patients with impetigo and exfoliative toxin production. No association with SmaI PFGE patterns

Abstract

Contrasting data are reported in the literature on the percent positivity rates (13.5%-100%) of exfoliative toxin (ET) production by S. aureus strains isolated from impetigo patients in Japan and in France. In the present study, by means of a recently available latex-test, toxin-A (ETA) or toxin-B (ETB) production was found in 67.6% of the 34 S. aureus strains isolated from 19 lesional (63.2%) and 15 non-lesional (nose or pharynx, 73.3%) areas of patients with impetigo (with no significant difference between the lesional and non-lesional isolates). ETA + ETB were produced by 44.1% of the strains, while 32.4% were non-producers. In contrast, the percent positivity rate observed in 40 [20 lesional and 20 non-lesional (nose or pharynx)] strains isolated in patients with atopic dermatitis was 15.0% (p < 0.001 both for the lesional and non-lesional strains versus impetigo, with no significant difference between lesional and non lesional strains). Finally, 26 strains from other types of specimens (abscesses, hemocultures, urine, central venous catheters, bronchoalveolar lavages) showed an 11.5% production rate of ETA or ETB (p < 0.001 versus impetigo strains, no significance versus atopic dermatitis). These data point to a significant association between exfoliative toxin production and S. aureus strains isolated in impetigo, both in lesional areas and in nasal/pharyngeal reservoirs. An attempt to correlate SmaI pulsed-field gel electrophoresis (PFGE) restriction patterns and exfoliative toxin production showed no significant association in either group.