A restricted biochemical scheme for the identification of enterobacteria, consisting of 12 enzymatic tests, of which 7 performed on the multitest TSI and MIU media (H2S, the production of acid and gas from glucose, fermentation of lactose/saccharose, mobility, urease and indol production) and 5 additional tests performed separately : lysindecarboxylase, phenylalanindeaminase, beta galactosidase, increase on citrate media and splitting of sodium malonate is proposed. Of 7782 coprocultures, 275 were selected on TSI and MIU media as belonging to one of the groups of known pathogenic enterobacteria ; 94.87% of these cultures were correctly identified by using the 5 additional tests alone. Of the 14 cultures that could not be listed taxonomically, 10 gave atypical reactions with at least one of these tests. The current use of this restricted scheme and the use of the more extensive sets only in doubtful cases presents a real advantage by reducing the volume of work and materials under satisfactorily accurate conditions for identification.

Bacteriological Techniques↗

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[Simplified diagnostic scheme for Enterobacteriaceae].

After testing 18 experimental variants against 40 reference strains belonging to different Enterovacteriaceae groups, the authors chose a multitest medium that permits concomitant testing of mobility, indol, lysinedecarboxylase and phenylalanine deaminase (MILP). In this medium, the reactions of 3734 strains belonging to the genera Escherichia, Shigella. Salmonella, Citrobacter, Klebsiella, Enterobacter, Serratia. Proteus and Providencia were concordant with the reactions in individual test media, taking as reference, in a proportion of 99.7 and 100%. The authors, associating the MILP medium to TSI agar, propose a simple scheme consisting of eight test which permits, within only 24 hours, the correct identification of the genus and sometimes of the species of cultures or isolated colonies from selective media.

Bacteriological Techniques↗