A critical question is the sensitivity of pathogen isolates to an investigational antibiotic, and whether they show any signs of developing resistance to a new treatment (from reduced sensitivity to full-blown resistance).
Multiple methods can be used to determine the sensitivity of pathogen isolates to particular antibiotics (antibiotic susceptibility testing, AST).
To speed up analyses, several automated AST systems have been developed that allow for high-throughput sample analysis. Traditionally, these have been based on phenotypic assays – direct assessment of the action of an antibiotic on the growth of isolates. Recently, for a limited number of pathogens, some rapid diagnostic tests have begun to be introduced. These provide a prediction of antibiotic susceptibility based on genetic analysis of isolates.
Developers need to work with AST system manufacturers to ensure that their new compound is incorporated into AST technology. Guidance on AST systems has been provided by the FDA.