title: Staphylococcus aureus small-colony variants are adapted phenotypes for intracellular persistence.
abstract: BACKGROUND
  Staphylococcus aureus is an important human pathogen of endovascular diseases, which can take a chronic course with a high relapse rate despite antimicrobial treatment. Thus far, persistent and antibiotic-refractory infections have been largely associated with a subpopulation of S. aureus, the small-colony variants (SCVs).
  
  
  METHODS
  In this work, we used endothelial cells to investigate infection with the highly virulent wild-type isolate (6850), 2 stable isogenic SCV phenotypes (hemB mutant IIb13 and JB1), and the complemented mutant.
  
  
  RESULTS
  All strains were highly invasive in endothelial cells but largely differed in host response induction. Microarray analysis showed that wild-type phenotypes up-regulated a large number of endothelial genes (including genes involved in innate immunity), whereas the SCVs did not cause these dramatic changes. The inflammatory response and cytotoxicity were strongest shortly after infection and largely decreased within the following days, which was accompanied by a fast elimination of intracellular wild-type bacteria. By contrast, SCVs survived within endothelial cells at high numbers.
  
  
  CONCLUSIONS
  S. aureus intracellular persistence via the development of an adapted subpopulation of SCVs most likely represents an important strategy of S. aureus to hide within the host cells, which could be a reservoir for chronic infections.
authors: Institutes of Medical Microbiology, Center of Clinical Research, University Hospital of Münster, Münster, Germany.
authors: Lorena
authors: L
authors: Tuchscherr
authors: Vanessa
authors: V
authors: Heitmann
authors: Muzaffar
authors: M
authors: Hussain
authors: Dorothee
authors: D
authors: Viemann
authors: Johannes
authors: J
authors: Roth
authors: Christof
authors: C
authors: von Eiff
authors: Georg
authors: G
authors: Peters
authors: Karsten
authors: K
authors: Becker
authors: Bettina
authors: B
authors: Löffler
mesh_terms: D002478:Cells, Cultured; D003593:Cytoplasm / Q000382:microbiology*; D042783:Endothelial Cells / Q000382:microbiology*; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D013211:Staphylococcus aureus / Q000254:growth & development* / Q000472:pathogenicity*