Minimal Bactericidal Concentration (MBC)



The Minimal Bactericidal Concentration (MBC) assay is performed as an adjunct to the MIC and is used to determined the concentration of antibiotic that is lethal to the target bacteria in vitro.


  1. From each MIC broth tube without visible growth, aliquot a 100 ml volume of the broth onto Mueller-Hinton agar and spread across the entire surface of the plate.

  2. Record the dilution of the subcultured MIC tube on each plate and incubate at 35oC until the next lab session.

  3. Following overnight incubation, examine the MBC plates for colony growth or lack of growth for each dilution subcultured. No growth indicates that the antibiotic was bactericidal at that dilution. Growth indicates that the antibiotic was bacteriostatic but not bactericidal at that dilution.


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