Improved procedure for identification of group D enterococci with two new media.

With the use of Pfizer selective enterococcus medium as a screening process, tyrosine decarboxylase (TD) medium and D-broth were devised for additional confirmation of the identification of group D enterococci. The semisolid TD medium was used in a method similar to inoculating a motility tube. TD activity was indicated by clarification of the medium near the line of inoculation because the insolubility of tyrosine provided an otherwise milky suspension. D-broth was used to show the tolerance of organisms to 6.5% NaCl at pH 8.2. In addition, enterococcal species (except Streptococcus durans) could also be demonstrated by the acid formation due to the fermentation of mannitol or arabinose. With this improved system, about 97% of enterococci could be accurately identified and confirmed.