title: Platelets enhance biofilm formation and resistance of endocarditis-inducing streptococci on the injured heart valve.
abstract: Infective endocarditis is a typical biofilm-associated infectious disease frequently caused by commensal streptococci, but the contribution of host factors in biofilm formation is unclear. We found that platelets are essential for in vitro biofilm formation by Streptococcus mutans or Streptococcus gordonii grown in human plasma. The biofilms were composed of bacterial floes embedded with platelet aggregates in layers, and a similar architecture was also detected in situ on the injured valves of a rat model of experimental endocarditis. Similar to planktonic cells, the streptococci in biofilms were also able to induce platelet aggregation, which facilitates multilayer biofilm formation. Entrapping of platelets directly enhances the resistance of streptococcal biofilms to clindamycin. Prophylactic antibiotics or aspirin can reduce but not prevent or abolish biofilm formation on injured heart valves. Therefore, the platelet is a host factor for commensal streptococci in the circulation to consolidate biofilm formation and protect bacteria against antibiotics.
authors.affiliation: Graduate Institute of Microbiology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan, ROC.
authors.forename: Chiau-Jing
authors.initials: CJ
authors.lastname: Jung
authors.forename: Chiou-Yueh
authors.initials: CY
authors.lastname: Yeh
authors.forename: Chia-Tung
authors.initials: CT
authors.lastname: Shun
authors.forename: Ron-Bin
authors.initials: RB
authors.lastname: Hsu
authors.forename: Hung-Wei
authors.initials: HW
authors.lastname: Cheng
authors.forename: Chi-Shuan
authors.initials: CS
authors.lastname: Lin
authors.forename: Jean-San
authors.initials: JS
authors.lastname: Chia
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000925:Anticoagulants / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D018441:Biofilms / Q000254:growth & development*; D001792:Blood Platelets / Q000382:microbiology*; D002981:Clindamycin / Q000494:pharmacology; D004195:Disease Models, Animal; D024881:Drug Resistance, Bacterial; D004696:Endocarditis / Q000382:microbiology*; D006351:Heart Valves / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D006805:Human Experimentation; D006801:Humans; D051381:Rats; D013290:Streptococcal Infections / Q000382:microbiology*; D054773:Streptococcus gordonii / Q000187:drug effects / Q000254:growth & development / Q000472:pathogenicity*; D013295:Streptococcus mutans / Q000187:drug effects / Q000254:growth & development / Q000472:pathogenicity*
chemical_list: D000900:Anti-Bacterial Agents; D000925:Anticoagulants; D002981:Clindamycin; D001241:Aspirin