Rapid antibiotic susceptiblity test using white-light interferometry

Antimicrobial resistance (AMR) has been coined the “silent pandemic” as it is a current and growing threat to global health. AMR has caused millions of deaths worldwide and leads a more than 10% treatment failure rate. Without effective antimicrobials, modern medical advances such as transplants, chemotherapy, and treatment of premature infants may become unsafe. One approach to reduce treatment failure is to improve diagnostics, i.e., more accurately determine if antimicrobials will work. With the existence of and potential for uncharacterized resistance mechanisms, phenotypic tests are necessary for clinical diagnostics. Current gold-standard tests for antimicrobial susceptibility, however, lack the sensitivity to rapidly differentiate susceptibility phenotypes and generally discount heterogeneous population responses. The best-case scenarios even for bulk population responses require tens of bacteria doubling times.

Our previous work uses the surface topography of a community to detect phenotypically heterogeneous populations. Now we take advantage of the coffee ring effect to develop a novel method of relative cell counting using volume from white light interferometry as a proxy for number of cells. This technique will reduce the number of doubling times required for detection. Quickly differentiating resistant phenotypes will enhance clinical treatment information which will improve antibiotic stewardship as well as treatment outcomes.