Systems and Methods for Determining Drug Resistance in Microorganisms

A method for determining the resistance of a microorganism to a drug by detecting growth of the microorganism in the presence of the drug, comprising:

• (a) incubating the microorganism in
• i) an isotopically-labeled growth medium comprising at least one drug and an isotopic label, wherein the microorganism incorporates the isotopic label into one or more biomarker molecules of the microorganism during growth in the medium;
• and
• ii) a control growth medium that lacks the drug and the isotopic label, wherein the one or more biomarker molecules of the microorganism remain unlabeled during growth in the medium;
• (b) applying the microorganism biomarker molecules of (a) to a mass spectrometry system to produce ion mass fragments of the biomarker molecules;
• (c) predicting a mass shift of the one or more unlabeled biomarker molecules of
• (a)(ii) using a first algorithmic analysis based on incorporation of the isotopic label of (a)(i);
• and
• (d) comparing the predicted mass shift of (c) with an observed mass of the one or more biomarker molecules of the microorganism growing in the isotopically-labeled medium with drug of (a)(i) using a second algorithmic analysis, based on which a probability that the biomarker molecules in the two media match can be determined, thereby determining the resistance of the microorganism to the drug.