Abstract

Staphylococcus epidermidis is a frequent cause of nosocomial infections. The major virulence factor is thought to be biofilm formation by the organism mediated by gene products of the icaADBC operon. In this research, biofilm phenotype and icaADBC gene carriage were studied in 50 S. epidermidis isolates from symptomatic patients (group A) and 50 skin isolates from healthy individuals (group B). Biofilm phenotype was shown by colony morphology on Congo red agar and the microtiter plate method was used for quantitative measurement of biofilm formation. Polymerase chain reaction was employed to detect the presence of icaADBC operon. The results showed no significant difference between the two groups of isolates for the potential to form biofilms by the two phenotypic assays or the amounts of biofilm produced by the two groups of isolates. On the other hand, ica gene carriage was more discriminatory and was observed in 30% of group A isolates compared to 8% of the skin isolates. We conclude that S. epidermidis isolates from patients with symptomatic infections are not necessarily more virulent from the skin contaminants and the capacity to form biofilms in vivo is influenced by environmental stimuli independent of theicaADBC gene products.

Key words:  Biofilm, Staphylococcus epidermidis, icaADBC, patients isolates, skin isolates.