Kirby-Bauer antibiotic testing

In Kirby-Bauer testing, white wafers containing antibiotics are placed on a plate of bacteria. Circles of poor bacterial growth surround some wafers indicating susceptibility to the antibiotic.

Kirby-Bauer antibiotic testing (KB testing or disk diffusion antibiotic sensitivity testing) is a test which uses antibiotic-impregnated wafers to test whether particular bacteria are susceptible to specific antibiotics. A known quantity of bacteria are grown on agar plates in the presence of thin wafers containing relevant antibiotics. If the bacteria are susceptible to a particular antibiotic, an area of clearing surrounds the wafer where bacteria are not capable of growing (called a zone of inhibition).

This along with the rate of antibiotic diffusion are used to estimate the bacteria's sensitivity to that particular antibiotic. In general, larger zones correlate with smaller minimum inhibitory concentration (MIC) of antibiotic for that bacteria. This information can be used to choose appropriate antibiotics to combat a particular infection.

Other images

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  Placing antibiotic disk on agar plates streaked with bacterial suspension(Inside a Laminar Airflow system)

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  The zones of inhibition using different concentrations of Ciprofloxacin

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  Multiple Antibiotic Sensitivity Test(click to see a better image)

See also

• Minimum inhibitory concentration

External links

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