Fidaxomicin highly effective for treating C. difficile infection

Dificid, a newer antibiotic for treating Clostridium difficile infection, was highly effective for treating initial and recurrent infections, including in patients with inflammatory bowel disease, according to the results of a multicenter retrospective study.

“The overall response rate to [Dificid (fidaxomicin, Merck)] was 90%,” Sahil Khanna, MBBS, of the division of gastroenterology and hepatology at the Mayo Clinic in Rochester, Minn., told Infectious Disease News. “Patients with no prior CDI episodes had signicantly higher response and lower recurrence rates compared with patients with prior episodes. All patients with IBD responded to daxomicin, with 19% experiencing recurrence, similar to the response and recurrence rates seen in our non-IBD population.”

Sahil Khanna

Because real-world data on fidaxomicin are limited, Khanna and colleagues reviewed a diverse cohort of patients with CDI who were treated with fidaxomicin at Mayo Clinic sites between August 2011 and July 2015. They included 81 patients with a median age of 55.9 years; 53% were women, 26% had IBD, 75% had prior CDI episodes (median, 1), 90% were previously treated with metronidazole, 89% were previously treated with vancomycin, and five patients were previously treated with fecal microbiota transplantation (FMT).

Overall, 90% of patients had complete response to treatment, while 10% had no response. Responders had a median of one prior CDI episode while nonresponders had a median of 2.5 (P = .01). The response rate was 100% in patients with an initial CDI episode, 96% in patients with one previous episode, and 82% in patients who had two or more previous episodes (P = .02).

“Our overall response rate was comparable to the response rates reported in phase 3 clinical trials of fidaxomicin,” Khanna said. “However, when we limited our cohort to a population similar to those used in the clinical trials (patients with zero or one prior CDI episodes), the response rate was higher at 98%.”

Overall, 19% of patients experienced recurrence of CDI within 8 weeks after the end of treatment, and patients without recurrence had a median of one previous CDI episode while patients with recurrence had a median of two previous CDI episodes (P = .005). No patients with initial CDI experienced recurrence compared with 23% of patients with one previous episode, and 29% of patients with at least two previous episodes (P = .005). All patients with IBD responded, 19% experienced recurrence, and four of the five patients with FMT responded with one experiencing recurrence.

No adverse events with fidaxomicin occurred, according to the researchers.

“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 CDI 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 CDI episodes,” Khanna said.

The results suggest that early use of fidaxomicin may be more beneficial than later use in the CDI course, but more real-world studies are needed to confirm this, Khanna and colleagues concluded. – by Adam Leitenberger

Disclosures: The study was supported by Merck. Khanna reports serving as a consultant for Rebiotix, and another researcher reports serving as a consultant for Merck.

Dificid, a newer antibiotic for treating Clostridium difficile infection, was highly effective for treating initial and recurrent infections, including in patients with inflammatory bowel disease, according to the results of a multicenter retrospective study.

“The overall response rate to [Dificid (fidaxomicin, Merck)] was 90%,” Sahil Khanna, MBBS, of the division of gastroenterology and hepatology at the Mayo Clinic in Rochester, Minn., told Infectious Disease News. “Patients with no prior CDI episodes had signicantly higher response and lower recurrence rates compared with patients with prior episodes. All patients with IBD responded to daxomicin, with 19% experiencing recurrence, similar to the response and recurrence rates seen in our non-IBD population.”

Sahil Khanna

Because real-world data on fidaxomicin are limited, Khanna and colleagues reviewed a diverse cohort of patients with CDI who were treated with fidaxomicin at Mayo Clinic sites between August 2011 and July 2015. They included 81 patients with a median age of 55.9 years; 53% were women, 26% had IBD, 75% had prior CDI episodes (median, 1), 90% were previously treated with metronidazole, 89% were previously treated with vancomycin, and five patients were previously treated with fecal microbiota transplantation (FMT).

Overall, 90% of patients had complete response to treatment, while 10% had no response. Responders had a median of one prior CDI episode while nonresponders had a median of 2.5 (P = .01). The response rate was 100% in patients with an initial CDI episode, 96% in patients with one previous episode, and 82% in patients who had two or more previous episodes (P = .02).

“Our overall response rate was comparable to the response rates reported in phase 3 clinical trials of fidaxomicin,” Khanna said. “However, when we limited our cohort to a population similar to those used in the clinical trials (patients with zero or one prior CDI episodes), the response rate was higher at 98%.”

Overall, 19% of patients experienced recurrence of CDI within 8 weeks after the end of treatment, and patients without recurrence had a median of one previous CDI episode while patients with recurrence had a median of two previous CDI episodes (P = .005). No patients with initial CDI experienced recurrence compared with 23% of patients with one previous episode, and 29% of patients with at least two previous episodes (P = .005). All patients with IBD responded, 19% experienced recurrence, and four of the five patients with FMT responded with one experiencing recurrence.

No adverse events with fidaxomicin occurred, according to the researchers.

“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 CDI 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 CDI episodes,” Khanna said.

The results suggest that early use of fidaxomicin may be more beneficial than later use in the CDI course, but more real-world studies are needed to confirm this, Khanna and colleagues concluded. – by Adam Leitenberger

Disclosures: The study was supported by Merck. Khanna reports serving as a consultant for Rebiotix, and another researcher reports serving as a consultant for Merck.