METHODS FOR THE ISOLATION OF FAECAL STREPTOCOCCI (LANCEFIELD GROUP D) FROM BACON FACTORIES

Abstract

SUMMARY: Two methods have been developed for isolating and enumerating group D faecal streptococci from localities such as bacon factories where they are heavily outnumbered by other organisms. The first depends on presumptive counts in a Lab‐Lemco‐peptone‐glucose broth (pH 6·0) containing 0·1% of thallous acetate with confirmation by streaking on tetrazolium agar. The other method involves direct plating on tetrazolium‐glucose agar (pH 6·0) containing 0·1% of thallous acetate. On the tetrazolium medium differentiation can be made between Streptococcus faecalis and its variants zymogenes and liquefaciens and the other group D organisms, Strep. faecium, Strep. durans and Strep. bovis .