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Antimicrobial Susceptibility test. testing sensitivity of the pathogen to specific antibiotics in order to choose best antimicrobial therapy. judged by determination of MIC and MBC. Minimum Inhibitory Concentration (MIC):
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Antimicrobial Susceptibility test • testing sensitivity of the pathogen to specific antibiotics in order to choose best antimicrobial therapy. • 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.
Antimicrobial Susceptibility test Zone of growth inhibition • Common methods • 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
Antimicrobial susceptibility test • E-test • The antibiotic diffuses from an impregnated strip containing gradient concentration an agar medium on which the test organism is growing.
Antimicrobial susceptibility test • Agar incorporation assays • The antibiotic dilutions are incorporated in an agar medium and spot inoculated with a number of test organisms. Incubation
Antimicrobial susceptibility test 16 8 4 0 64 32 Antibiotic concentration mg/ml • Broth dilution assays • Serial dilutions of the antibiotic in growth medium are inoculated with the test organism. • Automated Systems: VITEK.