Two of the most common antibiotic-resistant hospital superbugs could be eliminated by fecal transplantation of a healthy gut microbiome, say researchers.

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Fecal transplants in mice cleared K. pneumoniae

The study in mice has been published in PLOS Pathogens. It investigated the interactions between vancomycin-resistant Enterococcus faecium (VRE) and multidrug-resistant Klebsiella pneumoniae in the intestinal environment.

Dr. Eric Pamer, from the Memorial Sloan-Kettering Cancer Center in New York City, NY, and colleagues used a mouse model of intestinal colonization to test whether intestinal domination by either VRE or K. pneumoniae would offer resistance against colonization by the other pathogen.

The two pathogens together account for around 10% of serious hospital-acquired infections in the US. Both can colonize the gut and spread from there, and to other patients.

Fecal transplantation from healthy human donors has so far been found to be particularly effective for treating Clostridium difficile infection.

It is known that transplantation of feces from healthy mice can eliminate VRE from the intestine of densely colonized mice, say the researchers.

They colonized mice with VRE and K. pneumoniae at the same time and then treated them with either fecal microbiota transplants (FMT) or a sterile control solution for 3 consecutive days.

FMT reduced K. pneumoniae levels within 1 day

In this test of whether fecal transplantation can clear K. pneumoniae and concurrent infections with both the pathogens, the researchers found VRE and K. pneumoniae levels were similar in the feces before FMT and remained elevated in the control mice.

In the mice treated with FMT, however, K. pneumoniae density fell within a day - and became undetectable within 7 days in all the mice.

For VRE measures, these bacteria were cleared in 60% of the mice and in the remaining 40%, reduced by 1,000-fold.

On the question of whether VRE or K. pneumoniae dominated in the intestine and whether either would provide resistance against colonization by the other, the researchers found that each occupied the same intestinal sites.

The pathogens neither competed nor synergized after dense colonization of the mouse gut. But while "peacefully coexisting," the researchers found that the two pathogens differed with respect to stimulation and invasion of the colonic mucus, as shown in the pictures below.

Images of lab bacteria
Image credit: Silvia Caballero, CC-BY

The researchers say their findings:

"Uncovered previously unrecognized features of VRE and K. pneumoniae colonization and provide insight into the nature of pathogen coexistence, dissemination and ways to eradicate colonization."

Current efforts against antibiotic-resistant bacteria, the researchers add, "are focused on the identification of commensal bacterial species." That is, the focus is on the components of the healthy fecal transplant that mediate clearance of such bacteria.