Dual advance to the treatment of Clostridium difficile

Two recent decisions set to redefine the fight against Clostridium difficile. On April 5th Optimer announced that the FDA's advisory panel had recommended the approval of DIFICID; this followed, the previous day, the FDA's decision to clear Cepheid's diagnostic, Xpert C. difficile/Epi test.

Clostridium difficile infection (CDI), has become a significant medical problem in hospitals, long-term care facilities, and in the community and is estimated to afflict more than 700,000 people each year in the US. Bacterial infection causes colitis, severe diarrhea and, in the most serious cases, death. Patients typically develop CDI from the use of broad-spectrum antibiotics that disrupt normal gastrointestinal flora.

Current therapeutic options for CDI include the off-label use of metronidazole and oral vancomycin, the latter being the only FDA-approved treatment. However, approximately 20% to 30% of CDI patients who initially respond to these treatments experience a clinical recurrence following cessation of the CDI treatment.

Recommending Optimer's DIFICID (fidaxomicin) therefore represents a significant advance. This new antibiotic inhibits the bacterial enzyme RNA polymerase, resulting in the rapid killing of C. difficile. The narrow-spectrum profile of DIFICID eradicates C. difficile selectively with minimal disruption to the normal intestinal flora, while the alternative antibiotics used to treat CDI, metronidazole and vancomycin, have been shown to disrupt the gut flora. DIFICID facilitates the return of normal physiological conditions in the colon which may be responsible for reducing CDI recurrence rates.

In two Phase 3 trials for the treatment of CDI, DIFICID was equally effective in clinical cure when compared to vancomycin. DIFICID also demonstrated statistically significant reduction in recurrences and an increase in global cure rate, defined as cure without recurrence.

Rapid diagnosis is a key part of effective treatment of CDI. Cepheid's Xpert C. difficile test has been available in the United States since July 2009. This test allows for diagnosis within 45 minutes. Last week's FDA clearance relates to Xpert C. difficile/Epi which identifies a specific epidemic strain of C. difficile, known as 027, NAP1 or BI.

C. difficile 027 strain produces high levels of spores which pose significant infection control challenges and may also be associated with more frequent relapses and ultimately higher mortality rates.

Of interest DIFICID has shown good activity against C. difficile 027