An improved cooked meat medium for the detection of Clostridium botulinum.

A new medium composed of cooked meat and fluid thioglycolate broth was tested with 20 proteolytic and 11 saccharolytic strains of Clostridium botulinum. All of the proteolytic strains produced a black ring at the surface of the broth, presumably due to hydrogen sulfide production, while the saccharolytic strains produced white opaque rings. Since the black ring is formed rapidly and is easily seen, the new medium may be useful for the rapid identification of proteolysis in unknown isolates. Growth and toxin production were better in the new medium than in the usual cooked meat medium or in cooked meat medium plus 0.5% glucose. These results suggest that the new medium will be useful in facilitating identification of C. botulinum.