Interpret antimicrobial susceptibility test results by selecting an organism–antibiotic pair and entering the MIC value (µg/mL) or disk diffusion zone diameter (mm) to receive a susceptible, intermediate, or resistant classification based on simplified CLSI breakpoints. Use this tool in clinical microbiology lab training or when cross-checking automated AST results from the lab. Susceptible (S) means the infection is likely treatable with standard dosing, intermediate (I) suggests a borderline or dose-dependent response, and resistant (R) indicates the antibiotic is unlikely to be effective.

About Antimicrobial Susceptibility Testing

Antimicrobial susceptibility testing (AST) determines whether a bacterial isolate is susceptible (S), intermediate (I), or resistant (R) to a given antibiotic. Minimum inhibitory concentration (MIC) assays provide quantitative results in µg/mL, while disk diffusion (Kirby–Bauer) measures the zone of inhibition in mm. Results are interpreted using published breakpoints from CLSI (Clinical and Laboratory Standards Institute) or EUCAST. This tool implements a subset of CLSI M100 breakpoints for common clinical scenarios.