Expanding probiotic potential: Bacillus found to curb Staphylococcus bacteria in NIH study

11 Oct 2018 --- A “good” bacterium commonly found in probiotic digestive supplements can help eliminate Staphylococcus aureus, a type of bacteria that can cause serious antibiotic-resistant infections. This is according to a new study by the US National Institutes of Health scientists (NIH) and researchers from Mahidol University and Rajamangala University of Technology in Thailand. This study is a key example of the growing interest in finding applications for probiotics beyond the familiar area of digestive health.

The researchers, led by scientists at NIH’s National Institute of Allergy and Infectious Diseases (NIAID), found that Bacillus bacteria prevented S. aureus bacteria from growing in the gut and nose of healthy individuals.  

“Probiotics frequently are recommended as dietary supplements to improve digestive health,” says NIAID Director Anthony S. Fauci, M.D. “This is one of the first studies to describe precisely how they may work to provide health benefits. The possibility that oral Bacillus might be an effective alternative to antibiotic treatment for some conditions is scientifically intriguing and definitely worthy of further exploration.”

Innova Market Insights data have shown that new products with probiotics are on the rise, showing an annual growth rate of 8.5 percent (Global, 2013-2017). Lactobacillus, Bifidobacterium cultures and Streptococcus Thermophilus, in particular, are gaining ground in food and beverages. The market researcher further posits that Lactobacillus Reuteri and Bifidobacterium Animalis are expected to increase.

Methicillin-resistant Staphylococcus aureus (MRSA) is a well-known cause of serious disease, leading to thousands of deaths worldwide each year. S. aureus can live in the nose or gut without causing any harm, but can cause serious infections if the skin barrier is broken, or the immune system compromised.

Staph infections can be prevented by eliminating S. aureus colonization, but some decolonization strategies are controversial because they require considerable amounts of topical antibiotics, contributing to growing rates of antibiotic resistance.

Moreover, decolonization strategies can have limited success, partly because they target only the nose and bacteria quickly recolonized from the gut.

The study involved 200 volunteers in rural Thailand. This population was chosen because it would not likely be as affected by food sterilization or antibiotics as people in highly developed urban areas. 

The scientists first analyzed fecal samples from the study participants for bacteria correlated with the absence of S. aureus. They found 101 samples positive for Bacillus, primarily B. subtilis, which is the type found mixed with other bacteria in many probiotic products. 

Bacillus bacteria form spores that can survive harsh environments and commonly are ingested naturally with vegetables, allowing them to temporarily grow in the intestine. The scientists then sampled the same 200 people for S. aureus in the gut (25 positive) and nose (26 positive). They found no S. aureus in any of the samples where Bacillus were present.

In mouse studies, the scientists discovered an S. aureus sensing system that must function for the bacteria to grow in the gut. Intriguingly, all of the more than 100 Bacillus isolates they had recovered from the human feces efficiently inhibited that system.

Using chromatography and mass spectrometry techniques, the scientists identified fengycins, a specific class of lipopeptides, as the specific Bacillus substance that inhibited the S. aureus sensing system. Additional tests showed that fengycins had the same effect on several different strains of S. aureus. To further validate their findings, the scientists colonized the gut of mice with S. aureus and fed them B. subtilis spores to mimic probiotic intake. Probiotic Bacillus given every two days eliminated S. aureus in the guts of the mice. The same test using Bacillus where fengycin production had been removed had no effect, and S. aureus grew as expected.

The NIAID and Thai scientists next plan to test whether a probiotic product that contains only B. subtilis can eliminate S. aureus in people. 

“Ultimately, we hope to determine if a simple probiotic regimen can be used to reduce MRSA infection rates in hospitals,” says Michael Otto, Ph.D., the NIAID lead investigator.

Although a number of studies questioning the usage of probiotics have reached the mainstream media over the past months, this study is a good key example of the growing industry interest in finding applications for probiotics beyond the familiar are of digestive health. At Vitafoods Europe 2018, for example, key suppliers presented their probiotic solutions for areas such as women’s health, active recovery and skin health.