RESUMEN
Biofilms are microbial communities that are characterized by the presence of a viscoelastic extracellular polymeric substance (EPS). Studies have shown that polysaccharides, along with proteins and DNA, are a major constituent of the EPS and play a dominant role in mediating its microstructure and rheological properties. Here, we investigate the possibility of entanglements and associative complexes in solutions of extracellular polysaccharide intercellular adhesin (PIA) extracted from Staphylococcus epidermidis biofilms. We report that the weight average molar mass and radius of gyration of PIA isolates are 2.01×10(5)±1200 g/mol and 29.2±1.2 nm, respectively. The coil overlap concentration, c*, was thus determined to be (32±4)×10(-4) g/mL. Measurements of the in situ concentration of PIA (cPIA,biofilm) was found to be (10±2)×10(-4) g/mL.Thus, cPIA,biofilmAsunto(s)
Biopelículas/crecimiento & desarrollo
, Polisacáridos Bacterianos/química
, Albúmina Sérica Bovina/química
, Staphylococcus epidermidis/química
, Animales
, Adhesión Bacteriana
, Conformación de Carbohidratos
, Bovinos
, Elasticidad
, Enlace de Hidrógeno
, Concentración de Iones de Hidrógeno
, Polisacáridos Bacterianos/aislamiento & purificación
, Unión Proteica
, Electricidad Estática
, Viscosidad
RESUMEN
Biofilms production is a central feature of nosocomial infection of catheters and other medical devices used in resuscitation and critical care. However, the very effective biofilm forming pathogen Staphylococcus epidermidis often produces a modest host inflammatory response and few of the signs and symptoms associated with more virulent pathogens. To examine the impact of bacterial biofilm formation on provocation of an innate immune response, we studied the elaboration of the major complement anaphylatoxin C5a by human serum upon contact with S. epidermidis biofilms. Wild-type S. epidermidis and mutants of sarA (a regulatory protein that promotes synthesis of the biofilm-forming polysaccharide intercellular adhesin [PIA]) and icaB (responsible for postexport processing of PIA) were studied. C5a release, as a function of exposed biofilm surface area, was on the order of 1 fmol · cm · s and was dependent on the presence of PIA. Experimental results were used to inform a physiologically based pharmacokinetic model of C5a release by an infected central venous catheter, one of S. epidermidis' primary means of causing human disease. These simulations revealed that the magnitude of C5a release on a superior vena cava catheter completely covered with S. epidermidis would be lower than necessary to alert circulating leukocytes. Combined, the experimental and computational results are highly consistent with clinical observations in which the clinical signs of central line-associated bloodstream infection are often muted in association with this important pathogen.