Randomised Clinical Trial

A 12-Strain Bacterial Mixture Versus Faecal Microbiota Transplantation Versus Vancomycin for Recurrent Clostridioides difficile Infections

Anne Abildtrup Rode; Mahtab Chehri; Laura Rindom Krogsgaard; Kristine Klysner Heno; Anna Tølbøll Svendsen; Iben Ribberholt; Morten Helms; Jørgen Engberg; Kristian Schønning; Michael Tvede; Christian Østergaard Andersen; Ulrich Stab Jensen; Andreas Munk Petersen; Peter Bytzer


Aliment Pharmacol Ther. 2021;53(9):999-1009. 

In This Article

Abstract and Introduction


Background: A defined bacterial mixture could be a safer alternative to faecal microbiota transplantation (FMT).

Aims: To compare the efficacy of a 12-strain mixture termed rectal bacteriotherapy with either FMT or vancomycin for recurrent Clostridioides difficile infection (CDI) in an open-label 3-arm randomised controlled trial.

Methods: We screened all individuals positive for C difficile from May 2017 to March 2019. Persons with laboratory-confirmed recurrent CDI were included. Before FMT and rectal bacteriotherapy, we pre-treated with vancomycin for 7–14 days. Rectal bacteriotherapy was applied by enema on three consecutive days and FMT by enema once with possible repetition for two to three infusions within 14 days. The vancomycin group was treated for 14 days with additional five weeks of tapering for multiple recurrences. The primary outcome was clinical cure within 90 days. A secondary outcome was 180-day all-cause mortality.

Results: Participants in the FMT group (n = 34) were cured more often than participants receiving vancomycin (n = 31), 76% vs 45% (OR 3.9 (1.4–11.4), P < 0.01) or rectal bacteriotherapy (n = 31), 76% vs 52% (OR 3.0 (1.1–8.8), P = 0.04). Rectal bacteriotherapy and vancomycin performed similarly (P = 0.61). The mortality rate was 6% in the FMT group, 13% in the bacteriotherapy group and 23% in the vancomycin group. FMT tended to reduce mortality compared with vancomycin, OR 0.2 (0.04–1.12), P = 0.07.

Conclusions: Rectal bacteriotherapy appears as effective as vancomycin but less effective than 1–3 FMTs. FMT by enema with 1–3 infusions is superior to vancomycin for treating recurrent C difficile infections and might reduce mortality.


Clostridioides difficile (former Clostridium difficile[1]) infections pose a considerable concern with a risk of repeated recurrences after treatment. Clostridioides difficile infection can lead to severe diarrhoea and complications such as pseudomembranous colitis, sepsis and toxic megacolon. Furthermore, a high mortality has been reported.[2–4]

These infections frequently occur after antibiotic exposure, leaving a perturbed gut microbiota with reduced ability to resist colonisation and infection with C difficile. Thus, 20%-60% of patients experience recurrences, despite standard-of-care treatment.[2–4]

Recurrence of C difficile infection is associated with increased comorbidity, increased risk of hospitalisation and increased risk of dying.[5,6] Hence, more effective treatments for patients with recurrent C difficile infection are warranted.

Re-establishment of the gut microbiota in patients with recurrent C difficile infection can be efficient in preventing further recurrences. Faecal microbiota transplantation (FMT) using healthy donor stool was markedly more effective compared with oral vancomycin in two randomised controlled trials with convincing cure rates of 81%-90%,[7,8] and the treatment is now commonly used in clinical practice and recommended for treating multiple recurrences of C difficile infection in international guidelines.[9,10] However, the reported trials were small and the results might not be applicable to all individuals with recurrent C difficile infection. In addition, only one trial compared FMT with a pulse or tapering regimen of vancomycin for treating multiple recurrences as otherwise recommended by guidelines.[9–11] Hota et al could not confirm the earlier findings when comparing a single FMT by enema with oral vancomycin for 14 days followed by four weeks of tapering (cure rates 44% vs 58%).[12]

FMT has in general been shown to be safe, yet there are still important concerns about the safety. Moreover, there are difficulties in making the treatment widely available.[13] Risk of transferring infectious disease through FMT is of special concern—as recently supported when two recipients developed multiresistant bacteraemia transferred from a donor with one case being fatal.[14–16] Of note, the applied donor stool had not been tested according to current standards, which should preclude the presence of such multiresistant organisms.[17,18] Nevertheless, infusion of a well-characterised mixture of gut bacteria could be a safer and more standardised alternative to donor stool. In 1989, Tvede and Rask-Madsen introduced a defined mixture of enteric bacteria for rectal application termed rectal bacteriotherapy.[19] Rectal bacteriotherapy has been used for treating recurrent C difficile infection sporadically in Denmark for 30 years with stated cure rates of 64%-88% in case series, yet has not been evaluated in a randomised controlled trial.[20,21]

We report the results from a three-armed randomised controlled trial comparing the efficacy of rectal bacteriotherapy with either FMT by enema or oral vancomycin with tapering according to guidelines. We hypothesised that rectal bacteriotherapy and FMT were superior to vancomycin and that rectal bacteriotherapy was non-inferior to FMT for treating individuals with one or more recurrences of C difficile infection.