Minimum Inhibitory Concentration (MIC)
Susceptibility testing is indicated for any organism that contributes to an infectious process warranting antimicrobial therapy, if its susceptibility cannot be reliably predicted from knowledge of the organism’s identity. Susceptibility tests are most often indicated when the causative organism is thought to belong to a species capable of exhibiting resistance to commonly used antimicrobial agents. The lowest concentration of an antimicrobial agent that inhibits growth of an organism, as detected by lack of visual turbidity compared to a negative growth control, is designated the minimum inhibitory concentration.
Results are reported as resistant, intermediate or susceptible, based on National Committee for Clinical Laboratory Standards (NCCLS) reference methods.
Specimen requirement is a pure culture of the infecting bacteria. The organism should be placed in a proper mailing container and labeled as an etiologic agent. Agar plates are acceptable but should not be mailed.
