The researchers found that FMT offers both short- and long-term benefits for patients with C. difficile infection.
Conducted by researchers from the University of Minnesota and the University of Colorado-Boulder, the study reveals that fecal transplantation makes long-term healthy changes to the gut bacteria of patients infected with C. difficile - a finding they say could have important regulatory implications for the procedure.
Study co-author Michael Sadowsky, of the Microbial and Plant Genomics Institute at the University of Minnesota, and colleagues publish their findings in the journal Microbiome.
C. difficile infections are a major health concern in the US. According to the Centers for Disease Control and Prevention (CDC), the bacterium caused around half a million infections in 2011 and killed around 29,000 people within 30 days of diagnosis.
C. difficile is shed in feces. Infection with the bacterium can occur through contact with surfaces or items contaminated with feces. Infection with the bacterium causes colon inflammation, known as colitis, which can lead to fever, loss of appetite, nausea, diarrhea and abdominal pain.
While many C. difficile infections can be treated with antibiotics, the infection can keep coming back for some patients. In these cases, fecal microbiota transplantation (FMT) may be recommended.
FMT involves collecting the fecal matter of a healthy donor, before purifying it and placing it into the recipients' gut - most commonly via colonoscopy. It is believed to work by replacing the "friendly" gut bacteria that has been wiped out through overpopulation of C. difficile.
However, Sadowsky and colleagues note that, while past studies have shown that the fecal microbiota of FMT patients is similar to that of the donor, it is unclear as to whether the changes in gut bacteria as a result of FMT are long lasting.
Patients' gut bacteria remained healthy for up to 21 weeks after FMT
To find out, the team enrolled four patients with recurrent C. difficile infection to their study, all of whom were scheduled for FMT after treatment with antibiotics failed.
The researchers collected fecal samples from the patients both before FMT and daily for up to 151 days after the procedure.
The composition of bacteria in each fecal sample was assessed using high-throughout genome sequencing. Each pre- and post-FMT sample was compared. The samples were also compared with those of 10 other patients with recurrent C. difficile infection, and the sequences of each sample were compared with those of healthy individuals who were a part of the Human Microbiome Project.
In addition, the team assessed changes in the composition of gut bacteria over time in both the fecal samples from the four patients and fecal samples from the donor.
The researchers found that the gut bacteria of patients who underwent FMT was normalized shortly after the procedure. They were surprised to find, however, that while the composition of patients' gut bacteria changed following FMT, it remained healthy for up to 21 weeks.
Commenting on the findings, Sadowsky says:
"Our study shows that there are both short- and long-term changes in the fecal microbiome following transplantation. The diversity and types of microbes present fall into a cloud of possibilities represented by those of 'normal fecal microbiota.'
While we have many similarities in fecal microbiota amongst humans in general, there are individual differences that make us all unique, but do not affect apparent gut functioning."
Because the US Food and Drug Administration (FDA) class fecal microbiota as a "drug," they want to know the exact gut bacteria composition caused by FMT before it can be recommended as standard treatment for C. difficile infection - not just those with recurrent forms.
But Sadowsky and colleagues say that because FMT appears to alter gut bacteria composition to an array of diversities deemed healthy, such requirements from the FDA may not be applicable to the procedure.
"We [...] conclude that the dynamic behavior of microbiota needs to be taken into account in making comparisons between individuals, and should become an integral part of analysis of the success of FMT." they add.
Last month, a case report published in the journal Open Infectious Diseases revealed how a woman became obese after undergoing FMT from an overweight donor.
And more recently, a Spotlight feature from Medical News Today investigated the use of FMT for C. difficile infection and how the procedure is currently regulated.