Antibiotic tolerance and microbial biofilms

Increased tolerance to antimicrobial agents is thought to be an important feature of microbes growing in biofilms. We study the dynamics of antibiotic action within hydrodynamic flow chamber biofilms of Escherichia coli and Pseudomonas aeruginosa using isogenic mutants and fluorescent gene expression reporters and we address the question of how biofilm organization affects antibiotic susceptibility.

The dynamics of microbial killing is monitored by viable count determination, and confocal laser microscopy. Our work shows that the apparent increased antibiotic tolerance is due to the formation of antibiotic tolerant subpopulations within the biofilm. The formation of these subpopulations is highly variable and dependent on the antibiotic used, the biofilm structural organization and the induction of specific tolerance mechanisms.