Immune checkpoint inhibitor therapies such as ipilimumab, are increasingly being used as a treatment option for a variety of cancers, including metastatic melanoma and have demonstrated effectively a prolonged survival. These agents have an immunological mode of action that predisposes patients to a number of immune-related adverse events, colitis being one of the most commonly encountered complications. The pathogenesis for the development of colitis is unclear, and there is a growing consensus that the ecosystem of the gastrointestinal microbiota plays a significant role. Based on this suspected connection, studies are being carried out to explore the changes in the microbiota in patients on these medications who develop colitis. Conceivably, the modulation of the gut microbiota could offer a therapeutic benefit. Fecal microbiota transplantation is one therapeutic option that is currently being investigated, though there are still more data needed to evaluate its efficacy. In this review, we recapitulate the mechanisms of action of immune checkpoint inhibitors, their adverse events, with a focus on colitis and the role gut microbiota are suspected to play, and finally discuss the microbiota modulation therapies being investigated.

No abstract available.
Colonoscopy ; Microbiota

Inflammatory bowel disease (IBD) is a common diarrheal illness with gastrointestinal and extraintestinal manifestations and complications. The most common infectious complication associated with IBD is Clostridioides difficile infection (CDI). Active IBD predisposes to CDI due to alterations in the gut microbiome. C. difficile is a toxin producing bacterium leading to worsening of underlying IBD, increasing the risk of IBD treatment failure and an increased risk of hospitalization and surgery. Since the symptoms of CDI overlap with those of an IBD flare; it is prudent to recognize that the diagnosis of CDI is challenging and diagnostic tests (nucleic-acid and toxin-based assays) should be interpreted in context of symptoms and test performance. First line treatments for management of CDI in IBD include vancomycin or fidaxomicin. Recurrence prevention strategies should be implemented to mitigate recurrent CDI risk. One needs to monitor IBD disease progression and manage immunosuppression. The risk of recurrent CDI after a primary infection is higher in IBD compared to non-IBD patients. Microbiota restoration therapies are effective to prevent recurrent CDI in IBD patients. This review summarizes the epidemiology, pathophysiology, diagnostic testing, outcomes and management of both CDI and IBD, in CDI complicating IBD.

Inflammatory bowel disease (IBD) is a common diarrheal illness with gastrointestinal and extraintestinal manifestations and complications. The most common infectious complication associated with IBD is Clostridioides difficile infection (CDI). Active IBD predisposes to CDI due to alterations in the gut microbiome. C. difficile is a toxin producing bacterium leading to worsening of underlying IBD, increasing the risk of IBD treatment failure and an increased risk of hospitalization and surgery. Since the symptoms of CDI overlap with those of an IBD flare; it is prudent to recognize that the diagnosis of CDI is challenging and diagnostic tests (nucleic-acid and toxin-based assays) should be interpreted in context of symptoms and test performance. First line treatments for management of CDI in IBD include vancomycin or fidaxomicin. Recurrence prevention strategies should be implemented to mitigate recurrent CDI risk. One needs to monitor IBD disease progression and manage immunosuppression. The risk of recurrent CDI after a primary infection is higher in IBD compared to non-IBD patients. Microbiota restoration therapies are effective to prevent recurrent CDI in IBD patients. This review summarizes the epidemiology, pathophysiology, diagnostic testing, outcomes and management of both CDI and IBD, in CDI complicating IBD.