Probiotic markedly reduces S. Aureus colonization in phase 2 trial

Methicillin-resistantS. aureus, or MRSA, is familiar to many people as a cause of serious disease. Less well known is thatS. aureusoften lives in the nose, on the body and in the gut without causing any harm. However, if the skin barrier is broken, or the immune system compromised, these colonizing bacteria can cause serious skin, bone, lung, and blood infections.

The prevention ofS. aureusinfections 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 nasalS. aureuscolonization can be targeted with topical antibiotics without doing too much harm, but bacteria quickly can recolonize in the nose from the gut.

Probiotics, digestive supplements containing live microorganisms, may be a way to complement or replace antibiotics. ProbioticBacillusis especially promising because it is administered orally as spores that can survive passage through the stomach and then temporarily grow in the intestine. In prior studies, Dr. Otto's group discovered anS. aureussensing system needed forS. aureusto grow in the gut. They also found that fengycins,Bacilluslipopeptides that are part peptide and part lipid, prevent theS. aureussensing system from functioning, thereby eliminating the bacteria.

In the clinical trial, conducted in Thailand, the research team tested whether this approach works in people. They enrolled 115 healthy participants, all of whom were colonized naturally withS. aureus. A group of 55 people receivedB. subtilisprobiotic once daily for four weeks; a control group of 60 people received a placebo. After four weeks researchers evaluated the participants'S. aureuslevels in the gut and nose. They found no changes in the control group, but in the probiotic group they observed a 96.8%S. aureusreduction 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," Dr. Otto said. "We think we can target the 'bad'S. aureus而微生物群的构成tact."

The researchers also found that levels ofS. aureusbacteria in the gut far exceededS. aureusin the nose, which for decades has been the focus of staph infection prevention research. This finding adds to the potential importance ofS. aureusreduction in the gut.

"IntestinalS. aureus殖民已经明显了几十年,但金属氧化物半导体tly neglected by researchers because it was not a viable target for antibiotics," Dr. Otto said. "Our results suggest a way to safely and effectively reduce the total number of colonizingS. aureusand also call for a categorical rethinking of what we learned in textbooks aboutS. aureuscolonization of the human body."

The researchers plan to continue their work by testing the probiotic in a larger and longer trial. They note that their approach probably does not work as quickly as antibiotics, but can be used for long periods because the probiotic as used in the clinical trial does not cause harm. Study collaborators in Thailand are from Rajamangala University of Technology Srivijaya, and Prince of Songkla University.