Characteristics Named, as well coliforms or enterobacilli: . Found as normal flora in intestinal tract of humans and animals. . Gram-negative, non-spore forming, aerobic and facultative- anaerobic bacteria. . Most are motile. . Grow over a wide range of temperature in ordinary media. . All ferment glucose with acid production. . Oxidase negative. . Release endotoxin from their cell wall. . Some release exotoxin. Most of them have possessed three types of antigenes. These are : . H antigen-. Flagellar protein . Found in the flagella. . Possessed by motile enterobacteriaceae. . Heat labile and sensitive to alcohol May interfere with agglutination O by
. K antigen- .Capsular polysaccharide or protein
. Surroundes the cell wall. . Heat labile and may be associated with virulence May interfere with agglutination by O antisera . O antigen- .Outer membrane lipopolysaccharide. . Found in the cell wall of enterobacteriaceae.