A plating technique for screening intestinal coliform bacteria.

In investigations upon the alteration of the intestinal microflora of chickens by antibiotics added as supplements to rations, an important problem is the enumeration and identification of the coliform group of bacteria in intestinal contents. The importance of the coliform group in the chick's intestinal contents was demonstrated by Rhodes et al. (1954) in studies upon the vitamin-sparing effects of antibiotics. Considerable time and material must be expended to determine whether or not qualitative and quantitative changes occur within the coliform group in intestinal contents while chickens are maintained on the supplemented rations. The usual method for such determinations involves making direct isolations from a medium selective for the coliform group and subsequent identification of the isolated cultures. The screening procedure to be described in this paper is designed to reduce the time and materials required for isolations.