Quorum-sensing control of biofilm factors in Staphylococcus epidermidis.
Staphylococcus epidermidis is the most frequent cause of nosocomial sepsis and catheter-related infections, in which biofilm formation is considered to be the main virulence mechanism. Quorum-sensing systems have been recognized as important regulators of virulence and biofilm formation in many bacteria. There is a single quorum-sensing system in S. epidermidis encoded by the agr operon. To investigate quorum-sensing control of biofilm formation, we constructed an agr deletion mutant, assayed for the different stages of biofilm formation, and determined agr-dependent regulation of biofilm factors. The agr mutant showed increased biofilm formation, primary attachment, and expression of the autolysin AtlE, but lacked delta-toxin production. However, the level of polysaccharide intercellular adhesin expression was equivalent to the isogenic wild-type strain. In contrast to AtlE, which is known to influence primary attachment, delta-toxin appeared to exert its effect on attachment to polystyrene during later stages of biofilm formation. Importantly, addition of cross-inhibiting pheromones mimicked an agr mutation and significantly enhanced biofilm formation, which suggests that care should be used when treating S. epidermidis infections with cross-inhibiting peptides. Our data demonstrate the importance of quorum sensing in the establishment of a biofilm in this critical human pathogen.
Vuong
Cuong
C
Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840, USA.
Gerke
Christiane
C
Somerville
Greg A
GA
Fischer
Elizabeth R
ER
Otto
Michael
M
D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008855:Microscopy, Electron, Scanning; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000235:genetics / Q000378:metabolism; D010675:Pheromones / Q000494:pharmacology; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000378:metabolism; D011137:Polystyrenes; D011401:Promoter Regions, Genetic; D015398:Signal Transduction; D013212:Staphylococcus epidermidis / Q000254:growth & development* / Q000648:ultrastructure; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism
C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D010675:Pheromones; D011135:Polysaccharides, Bacterial; D011137:Polystyrenes; D015534:Trans-Activators; C113579:polysaccharide intercellular adhesin; C025971:staphylococcal delta toxin; D009238:N-Acetylmuramoyl-L-alanine Amidase