title: Clonal analysis of Staphylococcus epidermidis isolates carrying or lacking biofilm-mediating genes by multilocus sequence typing.
abstract: Staphylococcus epidermidis is part of the normal microflora of the human skin but is also a leading cause of device-associated infections in critically ill patients. Commensal and clinical S. epidermidis isolates differ in their ability to form biofilms on medical devices; the synthesis of biofilms is mediated by the icaADBC operon. Currently, the epidemiological relatedness between ica-positive and -negative isolates is not known; neither is it known whether the ica genes can spread to biofilm-negative strains through horizontal gene transfer. In this study, multilocus sequence typing (MLST) was employed for the clonal analysis of 118 S. epidermidis ica-positive and -negative strains. MLST revealed that the majority of ica-positive and -negative strains were closely related and formed a single clonal complex. Within this complex one sequence type (ST27) was identified which contained exclusively ica-positive isolates and represented the majority of clinical strains tested. ST27 and related ica-positive clones carried different SCCmec cassettes (conferring methicillin resistance) and the insertion sequence IS256. The findings suggest that the S. epidermidis infections analyzed in this report are mainly caused by a single clone (ST27) which occurs preferentially in hospitals and differs from clones in the community. It is hypothesized that the successful establishment of ST27 within nosocomial environments has been facilitated by the presence of genes encoding biofilm and resistance traits.
authors.affiliation: Institut für Molekulare Infektionsbiologie, Würzburg, Germany.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Kozitskaya
authors.forename: Michael E
authors.initials: ME
authors.lastname: Olson
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fey
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Witte
authors.forename: Knut
authors.initials: K
authors.lastname: Ohlsen
authors.forename: Wilma
authors.initials: W
authors.lastname: Ziebuhr
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000254:growth & development*; D004251:DNA Transposable Elements; D006801:Humans; D008969:Molecular Sequence Data; D009876:Operon; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; C487495:MecA protein, Staphylococcus epidermidis