Common Probiotic Appears to Eliminate S aureus Colonies

New research from the National Institutes of Health (NIH) suggests a widely available probiotic could be a secret weapon in the fight against Staphylococcus aureus.

In a newly published study, scientists show that the presence of the probiotic Bacillus, appeared to eliminate S aureus from the gut and nose.

Investigators from NIH’s National Institute of Allergy and Infectious Diseases working alongside scientists from 2 Thai universities, Mahidol University and Rajamangala University of Technology, made the discovery.

“This is one of the first studies to describe precisely how [probiotics] may work to provide health benefits,” said Anthony S. Fauci, MD, the NIAID’s director, in a press release. “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.”

Staph infections lead to tens of thousands of deaths around the world each year, according to the NIH. Many strains of the bacteria are antibiotic-resistant, making them a common hospital-acquired infection and thus a serious problem for hospitals and health care providers. The most well-known category of antibiotic-resistant Staphylococcus is Methicillin-resistant S aureus, better known as MRSA.

Though S aureus can be frightening bacteria, they can be harmlessly present in the nose or gut of a person without causing any harm. Only if the skin barrier is broken, or the immune system is weakened, does the bacteria pose an infection risk, the NIH said.

In the new study, investigators set out to find a new way to get rid of those colonies of S aureus, in the hopes that doing so would eliminate the risk of infection. Thus far, decolonization has been a tricky proposition, in part because it has relied on topical antibiotics, which can only combat bacteria in the nose and leave the gut’s bacteria untouched.

Investigators recruited 200 volunteers in rural Thailand. They then analyzed fecal samples from each participant with the hope of finding correlations between bacteria present in the sample and the absence of S aureus. Next, they tested for the presence of S aureus in the nose and in the gut.

A total of 26 patients were found to have S aureus in the nose, and 25 patients had the bacteria present in the gut; however, none of the patients whose fecal samples contained Bacillus tested positive for S aureus.

The investigators next moved to mouse models, finding that the introduction of any of the more than 100 Bacillus isolates gleaned from the human samples inhibited a sensing mechanism central to S aureus’ growth. The team later identified fengycins, a class of lipopeptides, as the key to blocking S aureus’ sensing system. The effect appeared to work in several different strains of S aureus.

One additional positive finding from the study was that Bacillus is a common ingredient in probiotic products, and thus relatively easy to access.

Senior author Michael Otto, PhD, chief of the Pathogen Molecular Genetics Section in the NIH’s National Institute of Allergy and Infectious Diseases Laboratory of Bacteriology, said the data suggest it might make sense for patients going to the hospital to take, or be given, a probiotic regimen including Bacillus.

“We think this is a logical consideration, but it must be tested first in trials,” he told Contagion®.

Otto said the probiotic pill could be given at admission and then on a daily or bi-daily basis throughout the hospital stay.

“The effect appears to be almost instantaneous (seen in mice after 1 day),” he said. “This would also have to be tested in a trial.”