Bob Morell poses a pertinent question for clinical microbiologists faced with
whether or not to identify Enterococcus to the species level. More than 90%
of the Enterococcus isolated from humans will usually be either E. faecalis
or E. faecium. Little clinical utility can be gained by speciating, except
knowing that E. faecium may be more likely to be resistant to Penicillin. In
terms of clinical outcome, I don't think speciating the enterococci will help
us very much. Clearly, it is much more important to be accurate in our
susceptibility testing of this isolate, especially since some of the
automated methods are not very accurate in identifying low-moderate levels of
vancomycin resistance. Unless there are epidemiologic reasons to do so, I
would not go to expensive lengths to speciate.
