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Streptococcus Durans N. SP.

1937; Elsevier BV; Volume: 20; Issue: 3 Linguagem: Inglês

10.3168/jds.s0022-0302(37)95679-0

1529-9066

James M. Sherman, Helen Upton Wing,

Bacterial Identification and Susceptibility Testing

In a previous paper (1) we described, under the cumbersome name of .streptococcushemothermophilus, an actively hemolytic streptococcus obtained from milk powder.This organism was shown to be non-pathogenic for mice, rabbits and guinea pigs, and to have physiologic characteristics which differentiated it clearly from the pathogenic hemolytic streptococci.Specifically, it was shown to be markedly different from such pathogens as S. pyogenes, S. equi, the" animal pyogenes," and S. mastitidis, by its lower minimum temperature of growth, a higher maximum temperature of growth, a higher thermal resistance, and the ability to produce a lower final pH in glucose broth.One object of this paper is to withdraw the previously applied name and suggest Streptococcus durans n. sp. as a more appropriate and convenient appellation.This name seems both suitable and descriptive in view of the Qrganism's rather extreme tolerance to heat and desiccation.The former name is objectionable in that it might appear to imply a relationship to S. thermophilus, whereas further study of it shows that S. d1lrans is in fact closely related to, and probably a member of, the" enterococcus group" of streptococci.The more important reason for this paper is that the organism has now been studied with additional tests which are of value in showing more clearly its relationships to other streptococci, as well as expanding the description of the species.In our former work it was shown that while this organism could be dearly differentiated from any adequately described species of streptococcus, it appeared to be most closely related to the Streptococcus fecalis group.Sherman and Stark (2) have shown that S. fecalis is able to grow in the presence of 6.5 per cent of sodium chloride, and also in media having an initial pH value of 9.6.'Unpublished work in this laboratory has indicated that the ability to grow under either of these conditions is limited among the streptococci to the members of the enterococcus group-S.fecalis, S. zymogenes, and S. liquefaciens.S. durans grows in these concentrations of salt and alkali, thus showing its close relationship to the enterococci.Sherman and Albus (3) used, among other tests, dilute medicinal methylene blue (1: 20,000) in milk as a means of differentiating Streptococcus lactis, which was not inhibited, from S. mastitidis, which was inhibited.Avery (4) showed that this test also has an especial value in differentiating