Although the number of cases is decreasing slightly, the most common cause of health-care associated infection in the US remains Clostridioides difficile, Jessica Allegretti, MD, explained at the American College of Gastroenterology postgraduate course on October 22, 2021.

“With almost 500K new cases annually, even with a downward trend C diff is still an epidemic,” she stated.

Dr Allegretti is director of clinical research and director of the Fecal Microbial Transplant Program and associate director of the Crohn’s and Colitis Center at Brigham and Women’s Hospital in Boston, Massachusetts.

She explained that for many years, metronidazole was a key agent in the pharmacological treatment of C diff. However, after 2000, trends began to emerge showing emergence of resistance to metronidazole, with failure rates of up to 20%. “This led to a paradigm shift to the use of vancomycin or fidaxomicin for treatment of C diff,” Dr Allegretti said.

In its recently published revised guidelines for treatment of C diff, the American College of Gastroenterology (ACG) recommends the use of oral metronidazole “only for very low-risk patients.”

Probiotics are not recommended for prevention of C diff or to prevent its recurrence, she added, noting that a study published in 2018 revealed that of 3 groups being treated for C diff, with antibiotics, one group was also given probiotics, some received autologous fecal microbial transplant (FMT), and one group received no additional therapy. Those on probiotics actually recovered more slowly than the spontaneous recovery group, suggesting that perhaps probiotics “stunted” the patient’s healing. The patients who underwent autologous FMT did best, she noted.

About 20% of patients infected with C diff suffer a recurrence, Dr Allegretti explained, “and with each recurrence, another recurrence becomes exponentially more likely.” While patients can be infected with the same strain or a new one, she said, “the vast majority are reinfected with same strain due to not having disinfected their homes thoroughly.”

In the case of recurrent, she stressed, “Do something different. If you used vancomycin before, use fidaxomicin the next time. Try a vancomycin taper. Just do something different.”

However, with the second or third recurrence of C diff, “you’re really talking now about going to FMT,” Dr Allegretti said.

FMT is the “instillation of minimally manipulated microbial communities from a healthy donor” into the gut of the patient. FDA considers FMT both a drug and a biologic and allows its use under enforcement discretion, Dr Allegretti explained. The agency has also set minimum screening requirements for donated materials, including tests for multidrug resistant organisms.

The donation can come from a patient-selected donor or from a stool bank, although, Dr Allegretti noted, such banks as Openbiome “have taken a real hit” due to the pandemic and fears of transmission of COVID-19 through stool.  Some medical institutions have begun to develop their own banks as a result.

Discussion with the patient should address these concerns, and other acute concerns about transmission of infections or longer-term complications. The next decision is the mode of delivery, which can be done via nasogastric tube, endoscopy, or capsule, among other methods.

She cautioned practitioners not to resume antibiotic treatment following FMT. “Patients often get decolonized of C diff, so you don’t need to retest.” Some patients are primary nonresponders, who should receive retreatment with FMT; in most cases the results are positive.

“Many companies have FMT products in development now,” Dr Allegretti stated, “and we’re seeing some positive Phase 2 and 3 trial data emerging.”

--Rebecca Mashaw

Allegretti, JR. Update on treating C difficile infection. Presented at American College of Gastroenterology annual meeting, October 22, 2021. Las Vegas, Nevada. [video]