Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Enterococcus Determination
Name: Arlene
Status: Other
Grade:  Other
Location: LA
Country: United States
Date: July 2007

What is biochemical test can differentiate Enterococcus faecium from Enterococcus faecalis?

Try this link-it has a table that shows how to distinguish gram positive cocci in the clinical lab. Enterococci are bile esculin positive, and grow in 6.5% salt, but E. fecalis is tellurite pos and E. faecium is tellurite neg.


What you need to do depends on what kind of sample you're working with and what kind of facilities you have access to use. There are many options, although don't get your hopes up for anything simple like gram-staining.

If you have a clinical sample of some kind and are not culturing, In Situ Hybridization might be a good way to go (J Med Microbiol 54 (2005), 937-944; Fluorescent in situ hybridization with specific DNA probes offers adequate detection of Enterococcus faecalis and Enterococcus faecium in clinical samples. Karola Waar, John E Degener, Marja J van Luyn, and Hermie JM Harmsen). Of course this requires a fluorescent microscope.

If you're able to culture, then you could use morphology (JOURNAL OF CLINICAL MICROBIOLOGY, June 2003, p. 2644-2646. Use of Colony Morphology To Distinguish Different Enterococcal Strains and Species in Mixed Culture from Clinical Specimens. Shabnam Qamer, Jonathan A. T. Sandoe, and Kevin G. Kerr), although this method uses some unusual ingredients. There are biochemical tests (Identification of Enterococcus Species Isolated from Human Infections by a Conventional Test Scheme, R. R. FACKLAM AND M. D. COLLINS, JOURNAL OF CLINICAL MICROBIOLOGY, Apr. 1989, p. 731-734) as well, although they're tedious.

I recommend you read these journal articles and decide which you're best equipped to execute. There are many more articles that provide different variations on these methods as well -- look them up on Google Scholar ( and decide (use the 'cited by' feature to find more recent variations). Since this is a pretty complex subject, and you didn't enter a grade, I am assuming you are college level or above. Virtually every university library will have subscriptions to these, so you should have access regardless.

Hope this helps,

Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory