Creighton University School of Medicine 1 article published in JoVE Genetics Digital PCR-based Competitive Index for High-throughput Analysis of Fitness in Salmonella Jeff A. Shaw1, Travis J. Bourret1 1Department of Medical Microbiology and Immunology, Creighton University School of Medicine This molecular-based approach for determining bacterial fitness facilitates precise and accurate detection of microorganisms using unique genomic DNA barcodes that are quantified via digital PCR. The protocol describes calculating the competitive index for Salmonella strains; however, the technology is readily adaptable to protocols requiring absolute quantification of any genetically-malleable organism.