Handbook of Culture Media for Food and Water Microbiology
Chapter K1: Kanamycin Aesculin Azide (KAA) agar
Published:06 Dec 2011
Special Collection: 2011 ebook collection , 2011 ebook collection , 2011-2015 food science subject collection
2011. "Kanamycin Aesculin Azide (KAA) agar", Handbook of Culture Media for Food and Water Microbiology, Janet E L Corry, Gordon D W Curtis, R M Baird
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The history of this medium is summarised by Mossel et al. (1978). It utilises (i) the selective inhibitory components azide and kanamycin and (ii) the indicator system aesculin and ferric iron for the isolation and differentiation of group D streptococci. Growth of the majority of unwanted organisms is suppressed, while sought organisms hydrolyse aesculin, producing black zones around the colonies due to the formation of black iron phenolic compounds derived from the aglucon. The selectivity of the medium can be increased by incubation at 42±0.5°C. The selective agents inhibit aesculin hydrolysis of species belonging to the Enterococcus avium and Enterococcus caecorum groups (Devriese et al., 1993). Aesculin-positive Lactobacillus strains should be excluded by confirmatory tests (Reuter, 1985). In water microbiology the medium is used as a confirmatory test for enterococci by the demonstration of aesculin hydrolysis (Anon., 2006).