Platelets enhance biofilm formation and resistance of endocarditis-inducing streptococci on the injured heart valve

Chiau Jing Jung, Chiou Yueh Yeh, Chia Tung Shun, Ron Bin Hsu, Hung Wei Cheng, Chi Shuan Lin, Jean San Chia

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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.

Original languageEnglish
Pages (from-to)1066-1075
Number of pages10
JournalJournal of Infectious Diseases
Issue number7
Publication statusPublished - Apr 1 2012
Externally publishedYes


ASJC Scopus subject areas

  • Infectious Diseases
  • Immunology and Allergy

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