Refinement of the Identification and Speciation Scheme of Fecal Streptococci

摘要

The EPA Schemes of identification and speciation of fecal streptococci were evaluated against nine standard streptococci obtained from the American Type Culture Collection (ATCC). The results of the biochemical tests were found to be contrary to those expected from the schemes. As an alternate method of speciation a number of carbohydrate fermentation tests were done using the EPA guidelines. Although it was not possible to separate the standard organisms following the guidelines, two of the standard organisms were found to be the same since they produced identical fermentation test results as well as having an identical colonial morphologies. Several tests were found to be useful in the confirmation of the fecal streptococcus group. These included: gram stain reaction, cellular morphology, colonial morphology on KF-Streptococcal Agar, thermal resistance, and negative catalase test. Results of these tests were found to be common to all the standard fecal streptococci as well as all of the environmental isolates. Also, a speciation method based on carbohydrate discs and phenol red agar plates made it possible to speciate all of the standard organisms as well as the environmental isolates. The disc method is simple, more economical, and requires less time than the method proposed by the EPA.