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Description:This 1972 image depicted a Mueller-Hinton agar culture plate that had been used in an antibiotic susceptibility test (AST). Known as the Kirby-Bauer method, each of the small labeled discs, or wafers, contained an antibiotic cocktail. The light halos surrounding each disc, also known as “reaction zones”, represented regions in which the bacteria on the agar’s surface did not thrive, due to their sensitivity to the antibiotic that had been soaked into these respective discs.
These tests which measure the presence or absence of a reaction zone, also take into account the pH of the medium, the concentration of the inoculum, i.e., bacteria, and a number of other factors. Using this method, the sensitivity of a bacterial strain to a given antibiotic, or combination of antibiotics, i.e., antimicrobials, may be determined.
High Resolution: Click here for hi-resolution image (4.75 MB)
Content Providers(s):CDC/ Gilda L. Jones
Creation Date:1972
Photo Credit:
CDC Organization
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.