The significance of nasal carriage of Staphylococcus aureus as risk factor for human skin infections.

The present study was designed to investigate the significance and the relationship between nasal carriage of Staphylococcus aureus and staphylococcal skin infections. Thirty-one S. aureus strains, isolated from 12 patients with chronic and recurrent skin infections, one patient with septicemia and one patient with otitis externa were studied. The staphylococcal strains were isolated from the site of infection and from the anterior nares of each patient. The identity of both strains of each pair could be demonstrated by determination of phenotypic properties and by genotyping of the isolates. The phenotypic properties included hemolytic activities, antibiotic resistance data, and the production of enterotoxins. The identity was additionally confirmed by phage-typing, by determination of the size and the number of repeats of the X region of spa gene, by determination of gene polymorphisms of coa gene and by macrorestriction analysis of the chromosomal DNA of the isolates by pulsed-field gel electrophoresis. The present results showed an identity of the S. aureus obtained from anterior nares and from skin infection of each patient indicating the importance of nasal carriage of these bacteria for development of human skin infection.