Fighting C. difficile infections

Antibiotics are an important means of treating infections and diseases caused by bacteria, such as pneumonia, strep throat, or urinary tract infections. Antibiotics work by killing harmful bacteria. Since their introduction in the mid-twentieth century, antibiotics have saved millions of lives.
But in recent years, overuse of antibiotics has caused many types of bacteria to become resistant to traditional treatment requiring higher doses and stronger antibiotics. The Centers for Disease Control and Prevention (CDC) calls antibiotic resistance “one of the world’s most pressing public health problems.”

Antibiotics and C. difficile

Although antibiotics are critically important medications when needed for serious infections, they also kill bacteria that normally live in the gastrointestinal tract. These beneficial bacteria are part of the healthy gut microbiome that protects us from invasion by microbes. If we are exposed to C. diff, a healthy microbiome keeps the C. diff bacteria in check. However, antibiotics poke holes in this bacterial ecology and weaken our ability to protect ourselves from microbes that can attack our colon.

So, C. diff infection (CDI) =requires two things: 1) a damaged gut microbiome and 2) exposure to C. diff spores. Once the sleeping spores are inside the gut, they can grow into the active forms that release toxins and cause disease.

If not controlled, CDI can cause a number of complications, including life-threatening colitis – inflammation of the colon. Antibiotics have been identified as a major risk factor for CDI.

The CDI tends to return in about 25% of cases after first-time antibiotic treatment. After the first recurrence of C. difficile infection, the risk of subsequent recurrence is 40% and increases to greater than 60% after a second recurrence. Recurrent infections tend to occur more commonly among older patients (>65 years of age).

Treatment options for those with multiply recurrent infections are limited. Two options include several weeks of vancomycin or a fecal transplant from a healthy screened stool donor. Neither approach has been approved by the FDA (Food and Drug Administration). Despite the high reinfection rate, antibiotics are one of the only approved treatments for C. difficile, leaving some patients to rely on antibiotic treatment indefinitely.

Ecobiotic therapies and C. difficile

A new investigational treatment that has shown promise in reducing recurrent C. difficile infection is an investigational research medication called SER-109 developed by Seres Therapeutics. SER-109 was designed to sustain a clinical response by rebuilding a healthy microbiome. Seres Therapeutics’ Ecobiotic® therapeutics, work to correct intestinal bacterial imbalance, improve the immune system, and restore the gut’s normal functioning by restoring healthy bacteria.

In a Phase 1b trial, SER-109 was associated with resolution of diarrhea in patients with a history of multiple recurrences of C. diff infection. In addition, the diversity of the microbiome in these subjects improved after dosing with SER-109. Previous research with SER-109 was found to significantly improve bacterial diversity and reduce recurrences of C. difficile infection in the majority of subjects tested. Seres Therapeutics is conducting a Phase 3 clinical study of SER-109 in patients with multiple recurrent C. difficile infection. The Food and Drug Administration (FDA) designated SER-109 as a Breakthrough Therapy in 2015, which means this research medication receives priority review by the FDA.

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