SPECIATION WITHIN THE GENUS BRUCELLA II

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Abstract
258 strains of brucellae, isolated from man and animals in Europe, Asia, Africa, and the Americas, were screened by the acriflavine agglutination test; 26 of these give positive tests and therefore are considered unsuitable for inclusion in an examination of the biochemical, dye sensitivity, and antigenic characteristics of smooth brucellae. All of the 232 smooth strains were tested for urease activity and for sensitivity to thionin, basic fuchsin, srystal violet, and pyronin. Both representative and atypical strains were examined also in respect to (1) sulfide production, (2) sensitivity to diethyldithiocarbamate when this was employed as a tableted " carbamate" reagent, and (3) sensitivity to azure A and safranin O. 214 of the 232 smooth strains fall into 3 well defined groups, corresponding to the 3 generally recognized species of Brucella, on the basis of the thionin, fuchsin, crystal violet, pyronin, urea, and carbamate tests. 5 strains are sensitive to both carbamate and the dyes and therefore require serological examination for their identification. 3 strains give sensitivity and biochemical tests indicative of B^ melitensis but react serologically like B. abortus. Both carbamate and urea are practical and reliable test reagents for identifying strains of brucellae; with but rare exceptions, only strains of B. melitensis give positive carbamate tests, and only strains.of B. suis are strongly urea positive. Tests/for production of hydrogen sulfide do not contribute significantly toward identification of spp. in the genus Brucella. Azure A and safranin O, particularly the former, are useful adjuncts to the traditional 4 dyes for the identification of atypical strains of brucellae.
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