title: Staphylococcus epidermidis biofilms induce lower complement activation in neonates as compared with adults.
abstract: BACKGROUND
  Staphylococcus epidermidis (SE) is an important cause of late-onset sepsis in neonates. SE frequently produces a polysaccharide intercellular adhesin (PIA) biofilm, important in the pathogenesis of these infections. Little is known about how the neonatal innate immune system reacts to SE biofilm-associated infections. Our hypothesis was that SE biofilms induce a lower complement activation in neonates as compared with adults.
  
  
  METHODS
  Cord blood from term infants (n = 15) and blood from adults (n = 6) were studied in an ex vivo whole-blood sepsis model. A PIA biofilm-producing strain (SE1457) and its isogenic mutant (M10), producing a non-PIA biofilm, were used.
  
  
  RESULTS
  Both SE biofilms induced stronger complement activation in adult than in cord blood (P ≤ 0.033). We found lower levels of antibodies toward both PIA (P = 0.002) and the whole bacterium (P = 0.001) in cord vs. adult blood. By contrast, the interleukin-8 (IL-8) and IL-6 secretion were higher in cord than in adult blood (P ≤ 0.002). The PIA biofilm induced stronger complement activation than the non-PIA biofilm.
  
  
  CONCLUSIONS
  We conclude that the neonatal complement system exhibits a maturational deficiency. This may reduce the ability of neonates to combat biofilm-associated SE infections.
authors.affiliation: Department of Clinical Medicine, Pediatric Research Group, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. hildegunn.granslo@uit.no
authors.forename: Hildegunn N
authors.initials: HN
authors.lastname: Granslo
authors.forename: Claus
authors.initials: C
authors.lastname: Klingenberg
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Fredheim
authors.forename: Ganesh
authors.initials: G
authors.lastname: Acharya
authors.forename: Tom Eirik
authors.initials: TE
authors.lastname: Mollnes
authors.forename: Trond
authors.initials: T
authors.lastname: Flægstad
mesh_terms: D000328:Adult; D018441:Biofilms; D003167:Complement Activation / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005312:Fetal Blood / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D015850:Interleukin-6 / Q000276:immunology; D016209:Interleukin-8 / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D013203:Staphylococcal Infections / Q000097:blood / Q000276:immunology*; D013212:Staphylococcus epidermidis / Q000276:immunology*; D018709:Statistics, Nonparametric
chemical_list: D015850:Interleukin-6; D016209:Interleukin-8; D011135:Polysaccharides, Bacterial; C113579:polysaccharide intercellular adhesin