Abstract: Susceptibility of sessile microorganisms to antimicrobial agents is tested with a method comprising growing the microorganisms on a support to form a biofilm, contacting the biofilm with a metabolic substrate having a chromogenic and/or fluorogenic moiety to continue a base-line metabolic activity of the biofilm, contacting the biofilm with one or more antimicrobial agents, determining an experimental metabolic activity of the biofilm by measuring a signal from the metabolic substrate, and comparing the base-line metabolic activity with the experimental activity. The biofilm may be grown in a device comprising a plurality of wells, each well having a planar bottom and at least on wall, a plurality of supports comprising discs for growing the biofilm, each support disposed within a well perpendicular to the planar bottom, and at least one cover that fittably seals the top of each well.

Abstract: This disclosure relates to methods and compositions to regulate biofilm formation. In particular, the disclosure provides methods and compositions that relate to regulation of biofilm formation by modulating the GacA/GacS regulatory system as well as methods and compositions for inhibiting small colony variant formation and reversion of resistant bacteria to a wild-type phenotype.