New blood culture medium.

A growth medium with a specific oxidation-reduction potential containing peptone, dextrose, sodium succinate, sodium lactate, gelatin, sodium bicarbonate and blue tetrazolium, an indicator dye, in a tris(hydroxymethyl)aminomethane buffer was used to detect the presence of microorganisms in blood. The procedure involved the introduction of blood (and bacteria) into the growth medium with the dye in its colorless state. As the bacteria grew, they converted the dye to a visible blue color (formazan) with their reductases. The growth medium served as its own contamination control, since microbial growth and be detected by a color change before it was used for blood culture. The experiments described herein demonstrate that the composition of this medium (with the dye) provides a unique system that is able to make a reliable and rapid detection of both gram-positive and gram-negative microorganisms and yeasts (Candida albicans) commonly associated with bacteremia.