Measures the ability of the specific organism to grow in the presence of a particular drug in vitro.
The goal of antimicrobial susceptibility testing is to predict the success or failure of an antibiotic being tested against a particular organism.
Information is reported in the form of minimum inhibitory concentration (MIC), which refers to the lowest concentration of antibiotic that inhibits visible growth of a microorganism.
The minimum inhibitory concentration is interpreted as susceptible, resistant, or intermediate as assessed by the Clinical and Laboratory Standards Institute criteria.
Susceptible indicates the microbial isolate is likely to be inhibited by the usually achievable concentrations of a particular antimicrobial agent.
Antimicrobial susceptibility testing limitations include: site of infection may not be able to achieve adequate antibiotic levels, some organisms carry enzymes in vivo that make in vitro antimicrobial sensisitvities less reliable, the presence of extended spectrum Beta-lactamases may not ne identified.