CORR Insights^®: Biofilm Antimicrobial Susceptibility Increases With Antimicrobial Exposure Time

Excerpt

Biofilm formation by pathogenic bacteria is a recognized virulence factor important in the persistence of chronic infections. When growing as biofilms, even antibiotic sensitive bacteria (as measured by the planktonic broth minimum inhibitory concentration [MIC] and minimum bactericidal concentration [MBC] methods) become highly tolerant of antibiotics. In part, this tolerance is due to the presence of a small fraction (< 1 %) of slow-growing “persister” cells and small colony variants which, according to some, cannot be killed by antibiotics alone, regardless of concentration [1, 5]. However, this would contradict other studies which report achieve complete sterilization of biofilms as the basis for the Minimum Biofilm Eradication Concentration (MBEC) assay [2]. …