Antimicrobial Susceptibility - MBC

The MBC is defined as the lowest concentration of an antimicrobial agent needed to kill 99.9 percent of the initial organism inoculum. Presently, specific guidelines for interpretation are not available; therefore, a clinician knowledgeable in both bactericidal testing and infectious diseases should be consulted to interpret the results.

The MIC is defined as the lowest concentration of an antibiotic which will inhibit the in vitro growth of an infectious organism. Results are reported in micrograms per mL. The interpretation of in vitro data is based on achievable serum concentrations, which may vary depending on dose, route of administration, degree of protein binding, site of infection, age and weight of the patient, and other factors.

For serious infections with coagulase-negative staphylococci, testing for oxacillin resistance will be performed in order to interpret the results for beta-lactam agents.

This test must be ordered for each antimicrobial agent tested.

The minimum turnaround time is 48 hours for nonfastidious, rapidly growing organisms and greater than or equal to 96 hours for fastidious, slow growing organisms.

An additional processing fee will be billed for all organisms submitted that are not in pure culture as indicated in the specimen requirements.

If species identification is not provided, identification will be performed at ARUP. Additional charges apply.