Fidaxomicin Effective for Patients Experiencing First C. difficile Infection Episode

Patients treated with fidaxomicin for their first Clostridium difficile (C. difficile) infection experienced no recurrences, according to the results of a new study.

Researchers from the Mayo Clinic examined 81 patients over a four-year period to assess efficacy and safety outcomes of fidaxomicin in a diverse cohort of C. difficile infected patients. Patients were observed at Mayo Clinic sites in Rochester, MN, Jacksonville, and Phoenix. Half of the patients were female and a quarter of the patients had inflammatory bowel disease. The team considered it an infection if a patient experienced three or more episodes of watery diarrhea in a 24-hour period and C. difficile was detected in the stool.

Three quarters of the patients had experienced an average of one prior episode, and most of those patients were treated with one or more courses of metronidazole or vancomycin.

After eight weeks of follow up, 90% of patients had a complete response. There did not appear to be a difference in treatment response when the patients were categorized by age, the researchers said. The rate of response in 20 patients who were experiencing their first C. difficile infection was 100%, compared to a 96% response rate in patients with one prior episode, and 82% in patients with two or more prior episodes.

If a patient experienced C. difficile infection after the eight-week period, it was classified as a new episode. The researchers additionally categorized the patients’ episodes as community derived or hospital onset depending on where symptoms could be traced.

In total, 14 of the 73 patients who demonstrated a response developed recurrent C. difficile infection within eight weeks of the treatment, the investigators reported. Again, there did not seem to be a difference in recurrence rates once the researchers classified the patients by age. Patients who did not develop recurrent C. difficile infections seemed to have fewer prior episodes than those with recurrent infection, the researchers explained.

For example, the investigators outlined, the rate of recurrent C. difficile infection in patients experiencing their first episode was zero percent, compared to about a quarter in patients with one prior episode and almost a third in patients with two or more prior episodes. There were 43 patients with none or one prior episode, in which five recurrences were observed within four weeks of treatment. All of those patients had one prior episode of C. difficile.

“Our overall response rate was comparable to the response rates reported in phase III clinical trials of fidaxomicin,” study author Sahil Khanna, MBBS, explained to MD Magazine in an email. “However, when we limited our cohort to a population similar to those used in the clinical trials (patients with 0 or one prior C. difficile infection episodes), the response rate was higher at 98%. We report a higher recurrence rate than seen in the trials, which was to be expected given that almost half of our population had two or more prior C. difficile infection episodes, putting them at higher risk of recurrent disease, likely due to decreased microbial diversity in patients previously treated with less selective antibiotics for prior C. difficile infection episodes.”

The paper, titled “Outcomes With Fidaxomicin Therapy in Clostridium difficile,” was published in the Journal of Clinical Gastroenterology.

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