Determination of Staphylococcal Types by Fermentation of Mannite. ∗

Abstract

The recent demonstration that different strains of staphylococci elaborate chemiclly distinct carbohydrates 1 has made it possible to separate these organisms into immunological types. 2 , 3 Differentiation of the types, however, is dependent upon precipitation of the specific polysaccharides in homologous antiserum, a technic requiring the extraction of the reactive substances. Since this procedure is somewhat cumbersome, necessitating time and facilities not always available, it seems desirable to introduce a simpler and more rapid means for the determination of types. Consequently, several methods have been studied for this purpose, and while none possesses an absolute accuracy, the reaction of fermentation of mannite appears to offer the best possibilities from the aspect of simplicity, rapidity and precision. It is proposed, therefore, to report in this communication the correlation of staphylococcal types to fermentation of mannite. 4

The data bearing on this study, arranged in the form of a protocol, are presented in Table I. It will be seen that an analysis has been made of 102 strains of staphylococci, which were tested in sequence as they were isolated in the diagnostic laboratory of Barnes Hospital. In 47 strains, the type was determined by precipitation of carbohydrates, while in 55, the staphylococci were separated presumptively into Type A or B depending chiefly on their derivations. In deciding upon pathogenicity of the given strains, complete reliance was placed on source, since attempts to differentiate the different organisms by animal-inoculation revealed frequent discrepancies between virulence for man and animal, thus indicating a species-variation difficult of reconciliation. Since the figures for both determined and presumptive types are closely comparable, it seems fair in summarizing to consider them as one. Thus, then, of 62 pathogenic strains, all Type A, 6 produced white pigment, and 56, varying degrees of yellow pigment.