IMViC Test:

Not all coliforms are of fecal origin; nonfecal coliforms like Enterobacter aerogenes are also commonly found in the environment.  Thus, coliforms may or may not signify fecal contamination of waters.  If coliforms are detected by using one or more of the tests that have been performed (membrane filtration, P-A, MTFM), one can determine using the IMViC tests whether they are fecal or non-fecal coliforms.

1. IMViC stands for Indole, Methyl Red, Voges Proskauer and Citrate.
2. Fecal coliforms like Escherichia coli are + + - - in the IMViC tests.
3. Nonfecal coliforms like Enterobacter aerogenes are - - + + in these tests.                                                Indole               Methyl Red            VP           Citrate
   Escherichia coli                          +                            +                    -             -
   Enterobacter aerogenes               -                              -                    +              +

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu