Enterococcus faecalis iis one of the top three most frequently-isolated species from hospital- associated infections of compromised patients and it can cause a highly fatal form of endocarditis. The medical importance of the enterococci is enhanced by their high degree of inherent and acquired resistance to antimicrobial agents, and by their propensity to act as a major conduit for the spread of resistance genes to more highly-pathogenic organisms. Enterococci are commonly isolated from biofilms formed on implanted medical devices, and colonization and growth on heart valves is also considered a form of biofilm growth. The biofilm environment is a likely niche for transfer of high-level vancomycin resistance from enterococci to Staphylococcus aureus. We have used genetic screens to identify a large number of novel genetic determinants of biofilm formation in vitro, and ongoing studies provide increasing evidence for the importance of many of these determinants in biofilms formed in vivo during infections. Many previously un-characterized enterococcal biofim determinants show significant conservation in a variety of important pathogens;if they are functionally conserved, the products of these genes comprise a pool of potential targets for the development of chemical inhibitors or vaccines that could block biofilm formation during infections produced by many different pathogens . The results from the current grant provide a strong foundation for answering important basic questions about the biology of enterococcal biofilm formation, as well as new approaches to increasing our understanding of bacterial pathogenic mechanisms.
The specific aims proposed to address these questions are to: 1. Use the information and resources from the present grant to identify critical signals and regulatory mechanisms involved in: a) the initial transition from planktonic to biofilm growth and, b) the subsequent development of the biofilm community. 2. Determine the effects of disruption of genes involved in enterococcal biofilm formation on virulence and identify functionally-conserved biofilm/virulence genes in S. aureus from the pool of novel biofilm determinants discovered in E. faecalis. 3. Identify determinants of biofilm-induced antibiotic resistance in the core genome of E. faecalis.

Public Health Relevance

The research proposed in this application is focused on the process by which a bacterium called Enterococcus faecalis is able to grow on surfaces in a structure called a biofilm. In recent years it has become widely accepted that bacterial growth in biofilms causes major differences in the physiology and behavior of bacteria from that observed in liquid cultures, and that biofilm formation is involved in the production of many, if not most bacterial infections. Our research will employing genetic techniques to identify and characterize previously un-studied enterococcal genes that are important in biofilm formation, and to determine whether similar genes in another important pathogen, Staphylococcus aureus, have the same biological functions as the enterococcal genes. If there is functional conservation of these genes, it could speed the development of new antimicrobial drugs or vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI058134-09
Application #
8582526
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Huntley, Clayton C
Project Start
2003-11-01
Project End
2015-11-30
Budget Start
2013-12-01
Budget End
2014-11-30
Support Year
9
Fiscal Year
2014
Total Cost
$365,226
Indirect Cost
$97,012
Name
University of Minnesota Twin Cities
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Leuck, Anne-Marie; Johnson, James R; Dunny, Gary M (2014) A widely used in vitro biofilm assay has questionable clinical significance for enterococcal endocarditis. PLoS One 9:e107282
Cook, Laura C C; Dunny, Gary M (2014) The influence of biofilms in the biology of plasmids. Microbiol Spectr 2:0012
Frank, Kristi L; Guiton, Pascale S; Barnes, Aaron M T et al. (2013) AhrC and Eep are biofilm infection-associated virulence factors in Enterococcus faecalis. Infect Immun 81:1696-708
Dunny, Gary M (2013) Enterococcal sex pheromones: signaling, social behavior, and evolution. Annu Rev Genet 47:457-82
Frank, Kristi L; Barnes, Aaron M T; Grindle, Suzanne M et al. (2012) Use of recombinase-based in vivo expression technology to characterize Enterococcus faecalis gene expression during infection identifies in vivo-expressed antisense RNAs and implicates the protease Eep in pathogenesis. Infect Immun 80:539-49
Wells, Carol L; Henry-Stanley, Michelle J; Barnes, Aaron M T et al. (2011) Relation between antibiotic susceptibility and ultrastructure of Staphylococcus aureus biofilms on surgical suture. Surg Infect (Larchmt) 12:297-305
Cook, Laura; Chatterjee, Anushree; Barnes, Aaron et al. (2011) Biofilm growth alters regulation of conjugation by a bacterial pheromone. Mol Microbiol 81:1499-510
Dunny, Gary M; Johnson, Christopher M (2011) Regulatory circuits controlling enterococcal conjugation: lessons for functional genomics. Curr Opin Microbiol 14:174-80
Henry-Stanley, Michelle J; Hess, Donavon J; Barnes, Aaron M T et al. (2010) Bacterial contamination of surgical suture resembles a biofilm. Surg Infect (Larchmt) 11:433-9
Ballering, Katie S; Kristich, Christopher J; Grindle, Suzanne M et al. (2009) Functional genomics of Enterococcus faecalis: multiple novel genetic determinants for biofilm formation in the core genome. J Bacteriol 191:2806-14

Showing the most recent 10 out of 13 publications