Dr. Stewart’s research focuses on the control of detrimental microbial biofilms. Biofilms are slimy, multicellular aggregates of bacteria or yeast that form on wetted surfaces. The persistent infections associated with catheters, heart valves, periodontitis (gum disease) and burn wounds are examples of biofilms that affect human health. When microorganisms group together in biofilms they evade killing by antimicrobial agents (disinfectants, antibiotics) that easily kill their free-floating counterparts. Dr. Stewart is interested in the mechanisms that protect microbes in biofilms. These include poor penetration of antimicrobial agents, variation in the physiological activity of microorganisms with biofilms, phenotypic variation, and the activation of stress responses. Dr. Stewart has also investigated alternative strategies for controlling biofilms including anti-biofilm coatings, chemical or enzymatic degradation of the matrix holding the biofilm together, and disruption of cell-to-cell communication.
Secor, P. R, James, G. A., Fleckman, P., Olerud, J. E., McInnerney, K., and P. S. Stewart. (2011)
Staphylococcus aureus biofilm and planktonic cultures differentially impact gene expression, MAPK phosphorylation, and cytokine production in human keratinocytes. BMC Microbiol 11:143.
Stewart, P. S., and M. J. Franklin. (2008) Physiological heterogeneity in biofilms. Nat Rev Microbiol 6:199-210.
Takenaka, S., Trivedi, H. M., Corbin, A., Pitts, B., and P. S. Stewart. (2008) Direct visualization of spatial and temporal patterns of antimicrobial action within model oral biofilms. Appl Environ Microbiol 74:1869-1875.
James, G. A, Swogger, E., Wolcott, R., Pulcini, E. D., Secor, P., Sestrich, J., Costerton, J. W., and P. S. Stewart. (2008) Biofilms in chronic wounds. Wound Rep Regen 16:37-44.
Rani, S. A., Pitts, B., Beyenal, H., Veluchamy, R. A., Lewandowski, Z., Davison, W. M., Buckingham-Meyer, K., and P. S. Stewart. (2007) Spatial patterns of DNA replication, protein synthesis, and oxygen concentration within bacterial biofilms reveal diverse physiological states. J Bacteriol 189:4223-4233.
Mah, T.-F., Pitts, B., Pellock, B., Walker, G. C., Stewart, P. S., and G. A. O’Toole. (2003) A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance. Nature 426:306-310.
Stewart, P. S., and J. W. Costerton. (2001) Antibiotic resistance of bacteria in biofilms. Lancet 358:135-138.
Costerton, J. W., Stewart, P. S., and E. P. Greenberg. (1999) Bacterial biofilms: A common cause of persistent infections. Science 284:1318-1322.