More data on the superiority of fidaxomicin versus vancomycin in adult patients has been published (Lancet 2012; 12: 281-9). While this study was a ‘double-blind, non-inferiority, randomized controlled trial,’ the data tilt in favor of fidaxomicin. This study enrolled 535 patients from 45 sites in Europe and 41 sites in U.S.
On an intention-to-treat basis, a clinical cure was noted in 88% of fidaxomicin group (200 mg BID x 10 days) and 86% of vancomycin group (125 mg QID x 10 days). Clinical cure was defined as resolution of diarrhea and no need for further treatment. The big difference was in recurrence risk: 13% of patients receiving fidaxomicin compared with 27% of patients receiving vancomycin. Recurrence was defined as development of three unformed bowel movements in 24 h, a positive stool toxin, and need for retreatment within 30 days of treatment completion. A sustained response (=”global cure”) was noted in 77% with fidaxomicin compared with 63% of vancomycin group.
Both groups of patients had similar variables: severity of illness, frequency of B1/027 strains, geographic distribution, concomitant antibiotics, previous C difficile infection, age, and inpatient status. In the group with concomitant antibiotics, fidaxomicin outperformed vancomycin with respect to cure rate: 90% versus 73%. Adverse reactions were similar as well (Table 7).
To underscore the severity of C difficile in this population, there was a significant mortality rate in both groups. 8% of patients receiving at least one dose of fidaxomicin died compared with 7% of vancomycin-treated patients.
Why does fidaxomicin have a lower recurrence rate? Probably due to a more narrow antibiotic spectrum and minimal effect on commensal gut flora. Fidaxomicin also has roughly eight times more potency in vitro than vancomycin against clinical isolates of C difficile.
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