The study was published in the Nature journal, Scientific Reports.
Dr Richard Murphy, research director at the Alltech European Bioscience Centre in Dunboyne, Ireland, and one of the authors of the work, says that, now more than ever, alternative strategies are required to further reduce antibiotic use on-farm while supporting restriction of antibiotics in animals to therapeutic use.
Studies like this, he says, as well as increasing industry knowledge around the interaction between prebiotics such as MRF and resistant microorganisms, show that it may be possible to strategically reduce antibiotic use naturally, promoting animal health without contributing to the growing health issue of antimicrobial resistance (AMR).
Dietary mannan-oligosaccharides (MOS) have been extensively studied and are widely used in animal nutrition. MOS has proven to be an effective solution for antibiotic-free diets, as well as providing support for immunity and digestion. Further refinements of yeast MOS have led to the isolation of a mannose-rich fraction (MRF) with enhanced benefits for intestinal health, says Alltech.
We spoke with Dr Murphy this morning to find out more.
The Alltech research scientists in Dunboyne have been exploring the mode of action of MRF for quite some time, he said.
“We have been interested in exploring what role MRF would play in influencing metabolism within cells or how cells grow. What we actually found was that it does have a classical prebiotic-like effect, it does stimulate the metabolism of cells. However, the way in which it stimulates the metabolism in cells is that it causes them to become more sensitive to antibiotics. What is happening is that, in the presence of MRF, cells are driven to a higher to state of metabolic activity, so that the bacterial cells metabolize faster, but in doing so, they also produce a lot more by-products internally, and some of those can be toxic. Those toxins stress the bacterial cells, and because those cells are stressed, they become more sensitive to antibiotics.”
While this current research was focused on E. coli, other work the team has been involved in would indicate a similar impact in Salmonella. “In the presence of MRF, we see a sensitization of resistant strains.”
In vivo data
Have these findings been shown in vivo?
“We have been looking at the microbial populations in poultry caecum and what we have found, again with MRF present, is that when you change the way in which these bacteria metabolize, or the way in which they grow, you actually change the diversity of the bacteria within the caecum and, not only that, we see that we get a decrease in resistant E. coli, a decrease in resistant Enterococci and we have shown that through [analysis] of cecal content of birds from production facilities.”
The work on the metabolism side showing how bacteria is made more sensitive to antibiotics is actually having an impact on the prevalence side, said Murphy. Upcoming research, soon to be published, will show that as bacteria becomes more sensitive to antibiotics, they becomes less prevalent, he added.
These insights illustrate how simple changes in the animal’s diet can have profound impact on the presence of pathogens and on a complex phenomenon like AMR, said the Alltech research lead.
“This is not about searching for an alternative to antibiotics but is a really good example of an alternative approach to a more judicious use of antibiotics,” he said.
It changes the way we use antibiotics.
If the antibiotic becomes more effective, then industry’s need to use it decreases, argues Dr Murphy. “If we are making the bacteria more sensitive to antibiotics, our requirement for them, perhaps, is lessened and the development of AMR is lessened as well.”
Source: Scientific Reports, Nature
Title: Yeast cell wall mannan rich fraction modulates bacterial cellular respiration potentiating antibiotic efficacy
DOI: https://doi.org/10.1038/s41598-020-78855-5
Authors: H Smith, S Grant, J Parker, R Murphy
