SCREENING OF STOOL SAMPLES FOR IDENTIFICATION OF VANCOMYCIN-RESISTANTENTEROCOCCUS ISOLATES SHOULD INCLUDE THE METHYL-ALPHA-D-GLUCOPYRANOSIDE TEST TO DIFFERENTIATE NONMOTILE ENTEROCOCCUS-GALLINARUM FROM ENTEROCOCCUS-FAECIUM

The methyl-alpha-D-glucopyranoside (MDG) test has been shown to be sup erior to motility testing in differentiating Enterococcus faecium from E. gallinarum. In the present study, 33 vancomycin-resistant enteroco ccus (VRE) isolates collected as part of a stool surveillance study we re compared by using motility and MDG. Motility testing identified all 33 isolates as E. faecium, whereas MDG identified 11 of the 33 isolat es as nonmotile E. gallinarum. The MDG results were confirmed by seque ncing the 16S rDNA V6-to-V8 region. We conclude that the MDG test is a necessary component of routine VRE screening.