Patent ID: 8609364

Claim:
A method for determining the antibiotic-resistance status of a microorganism, comprising: (a) contacting intact microorganisms with a resistance-determining affinity ligand under conditions whereby a microorganism/resistance-determining affinity ligand complex is formed and wherein said resistance-determining affinity ligand is not an antibody or antibody fragment; (b) layering said microorganism/resistance-determining affinity ligand complex on a density cushion in a container and centrifuging said container to separate said microorganism/resistance-determining affinity ligand complex formed in (a) from unbound resistance-determining affinity ligand; (c) determining the amount of resistance-determining affinity ligand bound to the intact microorganisms in the microorganism/resistance-determining affinity ligand complex; and (d) comparing the amount of resistance-determining affinity ligand bound to the intact microorganisms in the microorganism/resistance-determining affinity ligand complex to the amount of resistance-determining affinity ligand bound by a known antibiotic-sensitive or antibiotic-resistant strain of the same microorganism or a population of known antibiotic-sensitive or antibiotic-resistant strains; wherein if the intact microorganisms in the microorganism/resistance-determining affinity ligand complex binds a different amount of resistance-determining affinity ligand than is bound by the antibiotic-sensitive microorganism or the intact microorganisms in the microorganism/resistance-determining affinity ligand complex binds the same amount of resistance-determining affinity ligand as is bound by the antibiotic-resistant microorganism, the microorganism is identified as antibiotic-resistant, and wherein said method is carried out in less than about 240 minutes.