| Pseudomonas aeruginosa persists within the lungs of chronically infected cystic fibrosis (CF) patients as a multi-cellular community, whereby individual bacteria exist within a complex and highly heterogeneous extracellular matrix, termed a biofilm. Biofilm populations of P. aeruginosa display markedly elevated levels of resistance to both the host immune response and antimicrobial agents. This study addresses the role of several known virulence factors in biofilm formation and biofilm antibiotic resistance. Studies of P. aeruginosa strains with varying levels of alginate production have led to the proposal that excess alginate production may serve as an escape mechanism for bacterial dissemination from the biofilm. Studies using P. aeruginosa gacA− strains indicate that the GacA/GacS two component global regulatory system is an important and novel regulator of genes involved in biofilm formation and maturation. The three well-characterized RND-type multi-drug efflux pumps of P. aeruginosa were demonstrated to play only a minor role in the recalcitrant resistant nature of biofilms. This study also addressed the genetic differences which distinguish biofilms as a distinct mode of bacterial growth. (Abstract shortened by UMI.)... |
