title: Human plasma enhances the expression of Staphylococcal microbial surface components recognizing adhesive matrix molecules promoting biofilm formation and increases antimicrobial tolerance In Vitro.
abstract: BACKGROUND
  Microbial biofilms have been associated with the development of chronic human infections and represent a clinical challenge given their increased antimicrobial tolerance. Staphylococcus aureus is a major human pathogen causing a diverse range of diseases, of which biofilms are often involved. Staphylococcal attachment and the formation of biofilms have been shown to be facilitated by host factors that accumulate on surfaces. To better understand how host factors enhance staphylococcal biofilm formation, we evaluated the effect of whole human plasma on biofilm formation in clinical isolates of S. aureus and the expression of seven microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) known to be involved in biofilm formation by quantitative real-time PCR. We also evaluated whether plasma augmented changes in S. aureus biofilm morphology and antimicrobial resistance.
  
  
  RESULTS
  Exposure of clinical isolates of S. aureus to human plasma (10%) within media, and to a lesser extent when coated onto plates, significantly enhanced biofilm formation in all of the clinical isolates tested. Compared to biofilms grown under non-supplemented conditions, plasma-augmented biofilms displayed significant changes in both the biofilm phenotype and cell morphology as determined by confocal scanning laser microscopy (CLSM) and scanning electron microscopy (SEM), respectively. Exposure of bacteria to plasma resulted in a significant fold-increase in MSCRAMM expression in both a time and isolate-dependent manner. Additionally, plasma-augmented biofilms displayed an increased tolerance to vancomycin compared to biofilms grown in non-supplemented media.
  
  
  CONCLUSIONS
  Collectively, these studies support previous findings demonstrating a role for host factors in biofilm formation and provide further insight into how plasma, a preferred growth medium for staphylococcal biofilm formation enhances as well as augments other intrinsic properties of S. aureus biofilms. Consequently, these findings indicate that incorporation of host factors may be necessary to better replicate in vivo conditions and for the best utility of a clinical biofilm assay to evaluate the process of biofilm formation and treatments.
authors.affiliation: Department of Medicine, Infectious Disease Service, Brooke Army Medical Center, 3551 Roger Brooke Drive, JBSA Fort Sam Houston, TX 78234, USA. anthony.p.cardile.mil@mail.mil.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Cardile
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Sanchez
authors.forename: Meghan E
authors.initials: ME
authors.lastname: Samberg
authors.forename: Desiree R
authors.initials: DR
authors.lastname: Romano
authors.forename: Sharanda K
authors.initials: SK
authors.lastname: Hardy
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Wenke
authors.forename: Clinton K
authors.initials: CK
authors.lastname: Murray
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Akers
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology*; D015870:Gene Expression; D006801:Humans; D008826:Microbial Sensitivity Tests; D010949:Plasma / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000648:ultrastructure; D014640:Vancomycin / Q000494:pharmacology; D020713:Vancomycin Resistance
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; D003470:Culture Media; D014640:Vancomycin