testing sensitivity of the pathogen to specific antibiotics in order to choose best antimicrobial therapy. judged by determination of MIC and MBC. judged by determination of MIC and MBC. Minimum Inhibitory Concentration (MIC): laboratory term that defines the lowest concentration (μg/mL) of the antibiotic that is able to inhibit growth of the microorganism. Minimum Bacteriosidal Concentration (MBC): laboratory term that defines the lowest concentration (μg/mL) of the antibiotic that is able to kill 99% of the organism.

Common methods 1. Disk diffusion test: The antibiotic diffuses from an impregnated paper disc into an agar medium on which the test organism is growing. Disk diffusion test Kirby – Bauer test Zone of growth inhibition

2.E-test The antibiotic diffuses from an impregnated strip containing gradient concentration an agar medium on which the test organism is growing.

3.Agar incorporation assays The antibiotic dilutions are incorporated in an agar medium and spot inoculated with a number of test organisms.

4.Broth dilution assays Serial dilutions of the antibiotic in growth medium are inoculated with the test organism. 5.Automated Systems: VITEK. Antibiotic concentration  g/ml