Upload
elizabeth-stokes
View
220
Download
3
Embed Size (px)
Citation preview
Determination of MIC by Agar Diffusion Method
Minimum Inhibitory Concentration (MIC)
Definition: is the lowest concentration of an antimicrobial agent that will inhibit the visible growth of a microorganism after overnight incubation.
WHY?Clinically, MIC is not only used to determine the amount of antibiotic that the patient will receive but also the type of antibiotic used. This will lower the opportunity for microbial resistance to specific antimicrobial agents.
Common methods used for MIC determination
MIC by broth dilution method MIC by agar diffusion method
MIC by agar diffusion method Principle
Different gradient of AB solution Inoculation with the isolated pathogenic
microorganism Incubation for 24 hour Observation of the diameter of the zone of
inhibition as a parameter of the growth
Principle
Principle (Cont.)
Detailed procedure Materials:
Nutrient agar tube Sterile Petri dish Test tube with bacterial culture 2 sterile Pasteur pipettes Sterile Cork borer Sterile blade 4 Wassermann tubes with 4 different
concentrations of antibiotic
Detailed procedure
Precautions Pour the agar at optimum temp. (< 50oC)
Mix very well
Flame the blade very well after and before each cup
Don’t leave any agar debris inside the cup
Transfer the antibiotic from the low to the high concentration
AVIOD THE OVERFLOW
!!DO NOT INVERT THE PLAT!! Transfer the plate very carefully
Expected results
Results
Antibiotic Concentration µg/ml
Log concentration
Zone Diameter (mm)
100217
2502.3920
7502.8724
30003.430
Zone Diameter (mm)
Log ConcLog MIC
Results
Zone Diameter (mm)
Log ConcLog MIC
Results