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THE ENUMERATION OF FAECAL STREPTOCOCCI IN FOODS, USING PACKER'S CRYSTAL VIOLET SODIUM AZIDE BLOOD AGAR
Author(s) -
MOSSEL D. A. A.,
VAN DIEPEN H. M. J.,
DE BRUIN A. S.
Publication year - 1957
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1957.tb00102.x
Subject(s) - agar , sodium azide , crystal violet , agar plate , microbiology and biotechnology , bacteria , incubation , food science , biology , streptococcus , tetrathionate , chemistry , salmonella , biochemistry , genetics
SUMMARY: Packer's crystal violet sodium azide blood agar (Packer, 1943) used in poured plates at 36·1°, gave satisfactory recovery of pure cultures of Lancefield group D streptococci and completely inhibited the growth of 11 other species of aerobic and anaerobic food bacteria, including Strep. lactis (5 strains). Later, however, one group N streptococcus was obtained which did grow in Packer's agar at 36·1°. To eliminate this organism the incubation temperature had to be increased to 39·5°, using agar strips (Stirling et al. 1950) incubated in a water bath to secure strict temperature control. Under these conditions the recovery of typical group D streptococci was never consistently below 50% of the count in tryptone dextrose yeast extract agar at 31·1°.