Instrument and system for rapid microorganism identification and antimicrobial agent susceptibility testing

A system comprising:

• a system controller comprising:
• a processor;
• and
• a computer-readable storage medium storing instructions that, when executed by the processor, cause the system controller to perform operations comprising:
• extracting three or more subsamples from a sample comprising cells of a species of microorganism;
• diluting each subsample using a distinct dilution factor for each subsample;
• determining a cell concentration of each diluted subsample;
• approximating a non-linear effective dilution curve for the sample using the subsample cell concentrations and the distinct dilution factors;
• determining from the non-linear effective dilution curve a target dilution factor usable in diluting the sample to a target cell concentration;
• and
• diluting a portion of the sample using the determined target dilution factor.

A method for dynamically diluting a sample comprising cells of a species of microorganism to a target cell concentration, the method comprising:

• determining, using a processor, a target dilution factor usable in diluting the sample to a target cell concentration, the determining comprising:
• identifying a growth factor associated with the species of microorganism in the sample;
• diluting one or more subsamples of the sample using an associated sample dilution factor unique to each of the one or more subsamples to obtain one or more diluted subsamples;
• determining a cell concentration in each of the one or more diluted subsamples;
• creating a model of a non-linear dilution curve using the one or more determined cell concentrations and the associated sample dilution factors;
• determining the target dilution factor using the model of the non-linear dilution curve, the growth factor, and the target cell concentration;
• and
• diluting the sample using the determined target dilution factor to the target cell concentration.