65).Although results from older studies confirm that metronidazole is an effective treatment for Clostridium difficile colitis, findings of newer observational reports suggest unusually high rates of treatment failure and relapse.
During an 8-month period in 2003 and 2004, 207 patients with confirmed C. difficile colitis were treated with metronidazole at a Houston hospital. Only 50% responded completely to treatment: 28% responded but relapsed within 90 days after stopping treatment, 10% had persistent colitis that eventually responded to prolonged metronidazole or oral vancomycin, and 12% never responded. Presenting signs and symptoms did not predict treatment failure, nor did the number of days on antibiotics before or during treatment. The 90-day mortality rate was significantly higher in patients with treatment failure than in others.
Among patients diagnosed with C. difficile colitis at a Quebec hospital,
the proportion who required vancomycin after initial metronidazole
was about 10% annually from 1991 through 2002. In 2003 and 2004,
during a local C. difficile colitis epidemic, that number rose
to 26%. Among patients treated with metronidazole alone, 60-day
recurrence rates were about 20% from 1991 through 2002 and then
jumped to 47% in 2003 and 2004. Risk for recurrence was particularly
high (58%) among older patients (age,
65).
Differences in definitions of treatment failure and relapse might account for some of the discrepancy between older findings and these. Still, experts point to many possible reasons for more metronidazole failures, including the possibility of increasing drug resistance, increasing use of broad-spectrum antibiotics, and sicker, older patients in hospitals. Until larger trials clarify risks of drug failure and better treatments emerge, an editorialist suggests avoiding C. difficile colitis by limiting antibiotic use and unnecessary hospitalizations.
References:
1. Musher DM et al. Relatively poor outcome after treatment of Clostridium difficile colitis with metronidazole. Clin Infect Dis 2005 Jun 1; 40:1586-90.
2. Pépin J et al. Increasing risk of relapse after treatment of Clostridium difficile colitis in Quebec, Canada. Clin Infect Dis 2005 Jun 1; 40:1591-7.
3. Gerding DN. Metronidazole for Clostridium difficile-associated disease: Is it okay for Mom? Clin Infect Dis 2005 Jun 1; 40:1598-600.