A probiotic supplement was linked to substantial reductions in the colonization of Staphylococcus aureus. The findings were published in a study appearing in The Lancet Microbe. The research was conducted by researchers at the National Institutes of Health led by Michael Otto, Ph.D., an NIH senior investigator at the National Institute of Allergy and Infectious Diseases (NIAID).
 
S. aureus lives in the nose, body, and gut without causing any harm. However, if the skin barrier is broken or the immune system is compromised, the bacteria can cause serious skin, bone, lung, and blood infections.
 
The prevention of S. aureus infections using approaches to “decolonize” the body  has gained increased attention as the spread of antibiotic resistance limits treatment options. Some decolonization strategies are controversial because they also require large amounts of antibiotics, raising concerns about damage to the microbiota and the development of antibiotic resistance.  So far, it appears that only nasal S. aureus colonization can be targeted with topical antibiotics without doing too much harm, but bacteria quickly can recolonize in the nose from the gut, the authors report.
 
Previously, the team of researchers found that S. aureus has a sensing system it needs in order to grow in the gut. They also found that fengycins, Bacillus lipopeptides, prevent the S. aureus sensing system from functioning, thereby eliminating the bacteria.
 
Cutting Down on Colonization
 
In the clinical trial, the research team enrolled 115 healthy participants who were colonized naturally with S. aureus, with 55 participants receiving a B. subtilis probiotic once daily for four weeks, and the other group receiving a placebo.
 
After four weeks, researchers found no changes in the control group, but found that supplementation with the probiotic resulted in a 96.8% reduction of S. aureus in the stool and a 65.4% reduction in the nose.
 
“The probiotic we use does not ‘kill’ S. aureus, but it specifically and strongly diminishes its capacity to colonize,” Otto said. “We think we can target the ‘bad’ S. aureus while leaving the composition of the microbiota intact.”
 
The researchers found that levels of S. aureus in the gut far exceeded that in the nose, which for decades has been the focus of staph infection prevention research. This finding adds to the potential importance of reducing this bacteria in the gut.
 
“Intestinal S. aureus colonization has been evident for decades, but mostly neglected by researchers because it was not a viable target for antibiotics,” Otto said. “Our results suggest a way to safely and effectively reduce the total number of colonizing S. aureus and also call for a categorical rethinking of what we learned in textbooks about S. aureus colonization of the human body.”
 
The researchers plan to continue their work by testing the probiotic in a larger and longer trial. While probiotics don’t work as quickly as antibiotics, they note that the supplement can be used for longer periods based on the safety of the probiotic in the trial.