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Enumeration of Staphylococcus aureus in Foods with Special Reference to Egg‐yolk Reaction and Mannitol Negative Mutants
Author(s) -
Waart J. De,
Mossel D. A. A.,
Broeke R. ten,
Moosdijk A. van de
Publication year - 1968
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.1365-2672.1968.tb00368.x
Subject(s) - staphylococcus aureus , enumeration , microbiology and biotechnology , agar , mannitol , biology , yolk , bacteria , food science , genetics , biochemistry , mathematics , combinatorics
SUMMARY Chapman's medium designed for the enumeration of Staphylococcus aureus showed three shortcomings: (i) micrococci and many Bacillus spp. grow well on this agar and may obscure colonies of Staph. aureus ; (ii) some strains of Staph. aureus fail to dissimilate mannitol; among 1164 strains examined, mostly from clinical sources, 4.4 % appeared unable to dissimilate mannitol; (iii) the agar has inhibitory properties to sublethally impaired cells of Staph. aureus. The latter deficiency not being correctable, the suitability of the egg yolk‐tellurite‐glycine‐pyruvate agar (ETGPA) of Baird‐Parker (1962 b ) was evaluated. Of 522 strains of Staph. aureus of human and food origin 97.5 % developed characteristically and generally quantitatively on Baird‐Parker's agar. Baird‐Parker's medium has proved valuable in ecological studies on the occurrence and development of Staph. aureus in foods incriminated in staphyloenterotoxicosis: among 165 atypical black colonies isolated from 450 food samples only 2% were Staph. aureus.