Methods and compositions for reducing bacterial tolerance to antibacterials, disinfectants and organic solvents

A method for rendering bacterial cells more susceptible to a non-antibiotic bactericidal or bacteriostatic agent that is a substrate of an efflux pump comprising:

• administering to the bacterial cell an inhibitor of a gene locus or an expression product thereof, wherein the expression of the gene locus enhances expression of an efflux pump.

A method for rendering bacterial cells more susceptible to a non-antibiotic bactericidal or bacteriostatic agent that is a substrate of an efflux pump comprising:

• administering to the bacterial cell an inhibitor of the efflux pump.

A method for increasing the ability of bacterial cells to survive in an organic solvent comprising:

• enhancing expression in the bacterial cells of an organic solvent bacterial efflux pump by growing the bacterial cells in the presence of a non-mar/sox/rob agent that induces the overexpression of the organic solvent bacterial efflux pump.

A method for decreasing the ability of bacterial cells to survive in an organic solvent comprising:

• reducing expression in the bacterial cells of an organic solvent bacterial efflux pump by growing the bacterial cells in the presence of an agent that reduces the expression of the organic solvent bacterial efflux pump.

A method for testing the ability of a non-antibiotic composition to induce a multiple antibiotic resistance phenotype in a bacterium comprising

• (a) contacting the bacterium with the non-antibiotic composition,
• (b) determining the expression of a bacterial gene locus, the altered expression of which is indicative of induction of the multiple antibiotic resistance phenotype in the bacterium, and
• (c) comparing the result of (b) with a control, wherein altered expression of the bacterial gene locus indicates that the non-antibiotic composition induces the multiple antibiotic resistance phenotype in the bacterium.

The method of 38, wherein the composition is an inactive ingredient.

A composition comprising:

• a non-antibiotic bactericidal or bacteriostatic first agent and
• a second agent that inhibits the expression of or activity of an efflux pump.

A method for identifying an antibacterial composition which does not select or induce a multiple antibiotic resistance phenotype in a bacterium, comprising

• (a) contacting the bacterium with the antibacterial composition,
• (b) determining the expression of a bacterial gene locus, the altered expression of which is indicative of induction of the multiple antibiotic resistance phenotype in the bacterium, and
• (c) comparing the result of (b) with a control, wherein a lack of altered expression of the bacterial gene locus indicates that the antibacterial composition induces the multiple antibiotic resistance phenotype in the bacterium.