An in vitro diagnostic software program intended to be used for the interpretation of results of an in vitro diagnostic assay [e.g., minimum inhibitory concentration (MIC), mass spectrometry (MALDI-TOF)] performed on a microbial culture isolated from a clinical specimen, to determine the susceptibility, intermediate or resistance categorization of the microbial species. It is installed on an off-the-shelf computer or a web-based platform, and compares assay results (e.g., an acquired image, mass spectrum) to reference data to determine antimicrobial resistance (e.g., beta-lactamase, carbapenamase, and/or cephalosporinase activity). Results are used to guide patient treatment options.