Currently, pathogenic microorganisms are characterized for antimicrobial susceptibility on culture positive samples via growth in multiple wells with varying concentrations of different antimicrobials. This approach is very robust, and measures the “functional antimicrobial susceptibility AST” (the gold standard, according to clinicians) but is also very slow.
Some emerging techniques use rapid PCR type methods to characterize the presence of specific markers associated with resistance. This approach is somewhat faster, but more expensive. But it is also problematic in that this approach does not cover all known markers for resistance, not all resistance mechanisms have a known marker, and new resistance mechanisms are constantly emerging.
Other approaches speed up the process on a “post culture positive” sample by using accelerated methods (such as advanced imaging) to characterize bacteria growth. These are all incremental improvements because functional AST characterization still requires a culture positive sample, and many hours of testing after that. Our approach is the first (and to our knowledge, the only) one that can characterize the functional AST of the pathogen without requiring a culture step, and without requiring hours of testing.