S. aureus is an important cause of biofilm-related infections such as endocarditis, chronic osteomyelitis, corneal infections involving lens implants, and medical device-related infections. Infections involving staphylococcal biofllms are often very difficult to treat with antibiotics and may be recurrent or require surgical removal of the infected device or tissue. Antibiotic susceptibility tests used in the clinical laboratory measure the resistance of planktonic or free-floating bacteria and do not account for the fact that S. aureus biofilms are significantly more resistant to most antibiotics than planktonic bacteria. The characteristics of biofilms that make them refractory to antibiotic therapy are not well understood at this time. The long-term objective of this project is to characterize the properties of staphylococcal biofilms that make them refractory to antimicrobial chemotherapy. The immediate goal of the proposed project is to assess the role in antibiotic resistance of poly-N-acetyl glucosamine (PNAG), which plays a critical role in S. aureus biofilm formation. First, the influence of PNAG expression on antibiotic resistance of planktonic bacteria will be characterized. Next, a PNAG-independent biofilm model, based on the cross linking of bacteria via protein A / Fc-receptor interactions, will be implemented so that the role of PNAG in biofilm antibiotic resistance can be separated from its role in biofilm formation. In addition, the effect of PNAG on the penetration of fluorescently labeled antibiotics throughout biofilms will be analyzed by confocal microscopy. Finally, the interaction between PNAG and antibiotics commonly used to treat S. aureus infections will be characterized. We hypothesize that PNAG plays an important role in the resistance of S. aureus biofilms by acting as a physical barrier against antibiotic penetration and expect that knowledge of the role of PNAG in S. aureus biofilm resistance to antibiotics will advance the development of therapies used to combat these infections.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI061590-01
Application #
6814713
Study Section
Special Emphasis Panel (ZRG1-IDM-N (90))
Program Officer
Peters, Kent
Project Start
2004-06-15
Project End
2006-05-31
Budget Start
2004-06-15
Budget End
2005-05-31
Support Year
1
Fiscal Year
2004
Total Cost
$216,250
Indirect Cost
Name
Brigham and Women's Hospital
Department
Type
DUNS #
030811269
City
Boston
State
MA
Country
United States
Zip Code
02115
Cerca, Nuno; Jefferson, Kimberly K (2008) Effect of growth conditions on poly-N-acetylglucosamine expression and biofilm formation in Escherichia coli. FEMS Microbiol Lett 283:36-41
Patterson, Jennifer L; Girerd, Philippe H; Karjane, Nicole W et al. (2007) Effect of biofilm phenotype on resistance of Gardnerella vaginalis to hydrogen peroxide and lactic acid. Am J Obstet Gynecol 197:170.e1-7
Cerca, Nuno; Maira-Litran, Tomas; Jefferson, Kimberly K et al. (2007) Protection against Escherichia coli infection by antibody to the Staphylococcus aureus poly-N-acetylglucosamine surface polysaccharide. Proc Natl Acad Sci U S A 104:7528-33
Cerca, Nuno; Jefferson, Kimberly K; Maira-Litran, Tomas et al. (2007) Molecular basis for preferential protective efficacy of antibodies directed to the poorly acetylated form of staphylococcal poly-N-acetyl-beta-(1-6)-glucosamine. Infect Immun 75:3406-13
Cerca, Nuno; Jefferson, Kimberly K; Oliveira, Rosario et al. (2006) Comparative antibody-mediated phagocytosis of Staphylococcus epidermidis cells grown in a biofilm or in the planktonic state. Infect Immun 74:4849-55
Jefferson, Kimberly K; Cerca, Nuno (2006) Bacterial-bacterial cell interactions in biofilms: detection of polysaccharide intercellular adhesins by blotting and confocal microscopy. Methods Mol Biol 341:119-26
Jefferson, Kimberly K; Goldmann, Donald A; Pier, Gerald B (2005) Use of confocal microscopy to analyze the rate of vancomycin penetration through Staphylococcus aureus biofilms. Antimicrob Agents Chemother 49:2467-73
Kropec, Andrea; Maira-Litran, Tomas; Jefferson, Kimberly K et al. (2005) Poly-N-acetylglucosamine production in Staphylococcus aureus is essential for virulence in murine models of systemic infection. Infect Immun 73:6868-76