Agar dilution method

Minimum Inhibitory Concentration (MIC)

is the highest dilution (or lowest concentration) of antibiotic required to inhibit the growth of a bacterium. Conventional methods include agar and broth dilution methods.

Minimum Inhibitory Concentration (MIC)

pouring as slopes in 30 mL glass bottles.

Agar Dilution Method

• Performed by preparing two-fold dilutions of an antibiotic in a series of tubes containing nutrient agar.

• The bacteria is adjusted using 0.5 McFarland standard (1-2 x108 cells/mL) and then spot-inoculated in a grid that contains 104 to 105 cells/mL.

• MIC is determined by checking the lowest concentration of antibiotic where bacterial growth (presence of colony) is absent.

Agar Dilution Method

• Performed by preparing ___-fold dilutions of an antibiotic in a series of tubes containing _____ agar.

• The bacteria is adjusted using 0._ ________ standard (1-2 x108 cells/mL) and then spot-inoculated in a grid that contains 104 to 105 cells/mL.

• MIC is determined by checking the _______ concentration of antibiotic where bacterial growth (presence of colony) is absent.

Broth dilution method

for determination of MIC where no turbidity is detected in the tube containing the agent

Agar dilution test

for determination of MIC wherein no bacterial growth is observed on the plate containing the agent

Kirby-Bauer Disk Diffusion method

for determination of antibiotic susceptibility of bacteria against agents observed by measuring the clear zones around the antibiotic disks

Kirby-Bauer Disk Diffusion method

CANNOT be used in determinizing MIC

Etest

for determination of MIC where no bacterial growth is observed on the plate containing the agent