Maxson, TuckerBoyd, AnnLaufer, CraigBlancett, Candace2020-04-232020-04-23http://hdl.handle.net/11603/18232Here, we present an optimized colorimetric broth microdilution assay for Bacillus anthracis and Yersinia pestis that includes the redox sensitive dye resazurin added to the media. We found the assay results were easier to interpret and gave results significantly faster than the gold standard broth microdilution assay outlined in the CLSI guidelines. We obtained results in roughly half the time; 5h instead of 24h for B. anthracis and 28h instead of 48h for Y. pestis. Among 32 strains of B. anthracis tested with three different antibiotics and 25 strains of Y. pestis tested with 4 antibiotics, the assay provided categorical agreement of 100% and 99.7%, respectively. Essential agreement was the same for both bacteria, 99.3%. We also eliminated MIC determination subjectivity by measuring the color shift using a color detection app via smartphone and creating an equation to interpret the results.40 pagesen-USAttribution-NonCommercial-NoDerivs 3.0 United Statesminimum inhibitory concentrationbroth microdilutionBacillus anthracisYersinia pestisantibiotic resistanceText