Molecular epidemiology of Staphylococcus aureus colonization in a burn center

The aim of this study was to investigate carriage of Staphylococcus aureus by patients and health care workers (HCW) and to define the genetic relationship of S. aureus strains isolated from burn wounds. At admission, 19/55 (34.5%) patients carried S. aureus in their nose and/or throat. Of this group, 95% subsequently colonized their burn wounds with S. aureus. Molecular analysis showed that in 78% of these cases the burn-wound colonizing strain was identical to the strain carried at admission. Importantly, 23/36 (64%) patients who did not carry S. aureus at admission also developed burn-wound colonization. In this group, three dominant genotypes were identified as colonizing strains of burn wounds. These clones represented also the majority (59%) of S. aureus strains cultured from the nose and/or throat of health care workers and patients. If patients were admitted to one of the Intensive Care rooms burn wounds of non-carriers were not colonized with S. aureus as long as they remained in such isolation. Only patients who carried S. aureus at admission developed burn-wound colonization with that genotype they carried in the nose or throat. Both carriage in patients and health care workers and auto-infection play a crucial role in (cross-) colonization events.