The CRyPTIC project tested the susceptibility of each sample collected to 13 different antibiotics; since over 20,000 samples were collected, a high-throughput method was required. The consortium chose to use a bespoke dry 96-well microtitre plate (called UKMYC5) that was manufactered by Thermo Fisher and was a variant of their commercially available MYCOTB plate, but crucially included the new drugs, bedaquiline and delamanid, as well as the repurposed drugs, clofazimine and linezolid. Partway through the project, the plate design was optimised, creating the UKMYC6 plate.
Since each drug was present at 5-12 doubling dilutions, it is the minimum inhibitory concentration (MIC) that was measured. To assess whether each MIC corresponded with resistance or susceptibility, it is necessary to infer the epidemiological cutoff values (ECOFF or ECV) for each of the 13 drugs on the plates. That is the goal of this paper, published in the European Respiratory Journal.