Curtis J. Donskey, M.D., an investigator from the Cleveland VA Medical Center in Ohio, concluded that fidaxomicin is less likely than vancomycin to promote acquisition of VRE colonization in patients treated for CDI, likely due to inhibitory activity of fidaxomicin against many VRE strains and fidaxomicin's relative sparing of the intestinal flora including Bacteroides spp. The results showed that only 7% of patients treated with fidaxomicin acquired VRE versus 31% of vancomycin treated patients (p<0.001) from among a subset of 302 CDI patients, 248 of whom had a negative VRE stool sample upon entering the Phase 3 trial. In addition, 63% of the patients treated with fidaxomicin were found to retain greater than 100,000 Bacteroides bacteria per gram of stool versus only 13% of the vancomycin treated patients (p=0.004). These results provide further evidence that unlike vancomycin, fidaxomicin does not suppress Bacteroides bacteria, which is a major component of the intestinal flora and prevents C. difficile overgrowth. The Bacteroides sparing effect of fidaxomicin could be one of the reasons for the lower recurrence rate observed in the Phase 3 trial.