Patent ID: 7335485

Claim:
A method of determining antibiotic susceptibility of a microorganism comprising: a) admixing a test microorganism whose susceptibility is to be determined with an antibiotic to which susceptibility is to be assayed, a permeabilizing agent for the test microorganism present in a non-growth-inhibiting microorganism-permeabilizing effective amount, and a strain of microorganism with known susceptibility for said antibiotic to form an assay culture; b) providing a control comprising the test microorganism, the antibiotic, and said strain of microorganism, without a non-growth-inhibiting microorganism-permeabilizing effective amount of a permeabilizing agent; c) incubating said assay culture and control under appropriate conditions and for a time sufficient to determine the susceptibility of the test microorganism to said antibiotic; and d) comparing growth in the assay culture to growth in the control, whereby, significantly more growth or a distortion in a zone of inhibition in the assay culture is indicative of resistance of the test microorganism to the antibiotic attributable to inactivation of the antibiotic.