A study published in Science shows new strains of microbes from the donor were more likely to colonize the patient’s intestines if that particular species exists in the patient’s gut.

The finding suggests that by matching donors to patients, the success of faecal microbiota transplant can be considerably increased. Moreover, focusing on bacterial strands instead of species could also improve the effectiveness of the novel therapy in conditions where it’s currently not effective.

The bulk of the population has Escherichia coli in their intestines but different people have different strains of the species; some strains can cause health issues. By differentiating between the strains, the researchers could track if the microbes in a patient’s gut after a stool transplant were their own or came from the donor.

Using this approach we can examine if, for instance, an antibiotic-resistant strain is replaced by a non-resistant one, said lead researcher Professor Willem de Vos, of the Wageningen University, Netherlands. It could then aid in designing stool transplants for other conditions besides recurrentClostridium difficile infections.

The study is part of a clinical trial on the use of stool transplants as a treatment modality for metabolic syndrome. The data is collected from only 10 participants but there are strong indications that donor-patient compatibility plays a bigger role than previously thought; transplants from one donor led to very different outcomes in three individual patients.