Pulsed-field gel electrophoresis of Staphylococcus aureus isolates from atopic patients revealing presence of similar strains in isolates from children and their parents.

Skin colonization with Staphylococcus aureus is often associated with atopic dermatitis, and staphylococcal enterotoxins have been implicated in the etiology of atopic disease. In this study, the colonization of patients with atopic dermatitis and their parents was investigated in order to evaluate the possibility of intrafamiliar transmission. S. aureus strains were isolated from 30 of 45 patients (66%). In 19 of 29 families (65%), at least one parent carried S. aureus, and the overall colonization rate of the parents was 48%. All strains were typed by pulsed-field gel electrophoresis (PFGE), and the presence of enterotoxin genes in the strains was assayed by multiplex PCR. A high percentage (84%) of the isolates present on the children and on at least one of their parents displayed identical PFGE and enterotoxin patterns as well as identical antibiotic resistance profiles, indicating intrafamiliar transmission. Forty-five percent of the strains did not carry any enterotoxin gene. The most frequently found enterotoxin genes were seg and sei, which were present in 36% of the strains, and seb, which was found in 24% of the strains. The other toxin genes occurred only in low frequencies. Most strains were resistant to penicillin (82%), and 15% showed resistance to more than one antibiotic. Intermediately-vancomycin-resistant S. aureus or methicillin-resistant S. aureus strains were not detected. In conclusion, this study indicates that the colonization rate of parents of atopic children is rather high and may increase the risk of recolonization of the child.