Boric Acid As A Selective Bacterio-Static Agent

Abstract

A fluid medium is described, containing in every 100 c.c. of peptone water 0·25 g. lactose, 0·5 g. boric acid and 1 g. sodium sulphite (anhydrous). It shows a marked selective action.The test gives satisfactory readings within 24 hours of incubating at 37°C. I am of the opinion that all strains capable of growth in this medium may be regarded as of definite sanitary significance; they are most likely of faecal origin, while those which fail to grow are of minor sanitary importance.I hope that the boric sulphite test may prove a useful adjunct to the bacteriological examination of samples of water.