Study: Probiotic supplement effective against antibiotic-resistant staphylococcal infections

According to a new study, a probiotic supplement appears to rid the body of a type of bacteria that can cause serious antibiotic-resistant infections.

More research is needed, but experts said the work could lead to a way to prevent infections with the bacteria, called Staphylococcus aureus.

S. aureus usually causes skin infections, but can also lead to serious, life-threatening illness if it enters the bloodstream. Of particular concern are methicillin-resistant strains of S. aureus (MRSA) – the so-called “superbugs” that are resistant to many antibiotics used to treat staph infections.

Given this, researchers have looked for ways to prevent staph infections in the first place.

The human body naturally harbors S. aureus, with the nose and skin being two hot spots. Researchers have therefore tried using topical antibiotics or antiseptics to eliminate staph from these areas of the body in certain high-risk situations, such as when people are hospitalized or undergoing kidney dialysis.

But success has been limited, said Michael Otto, principal investigator at the US National Institute of Allergy and Infectious Diseases.

He pointed to what is thought to be a major hurdle: the gut is an even bigger “reservoir” for S. aureus, and it quickly replenishes supplies that are depleted in the nose or skin.

This is a daunting problem, as there is no sure way to specifically target S. aureus in the gut.

“That’s just not possible with oral antibiotics,” Otto said. This, he explained, would indiscriminately eliminate “good” bacteria that normally live in the gut and support vital body functions.

For the new study, Otto and his colleagues tried a different tactic: a probiotic called Bacillus subtilis. They chose this bacterium based, in part, on a curious finding from a 2018 study: People who had Bacillus in their stool never harbored S. aureus in their bodies.

Not everyone carries a permanent “colony” of S. aureus, Otto explained. Research suggests that about a third of the population does, for reasons that are unclear.

But carrying Bacillus could be a protective factor. In their previous work, Otto’s team also discovered that most types of Bacillus, including most strains of B. subtilis, secrete substances that specifically prevent S. aureus from taking hold in the body.

All of this raised the possibility that Bacillus could be used to selectively deplete S. aureus while leaving other gut bacteria alone.

The current study involved 115 healthy adults from Thailand whose nasal and stool samples indicated that they were lifelong carriers of S. aureus. They were randomly assigned to take either the B. subtilis supplement or placebo capsules daily for 30 days.

Ultimately, the study found that the probiotic nearly wiped out S. aureus in the gut, reducing the amount in participants’ stool samples by 97%, on average. It also reduced bacteria levels in nasal samples by two-thirds.

Equally important, Otto’s team found that there was no evidence that the probiotic had any adverse effects on the normal bacterial makeup of the gut.

The results were recently published in the journal Lancet Microbe.

An infectious disease specialist who was not involved in the trial called the results “very interesting”.

However, more research is needed to determine whether the probiotic is safe and effective for long-term use — and whether it actually prevents staph infections, said Dr. Aaron Glatt, spokesperson for the Infectious Diseases Society. of America.

At this point, he said, no one should be running to the health food store to stock up on Bacillus. For one, supplements aren’t regulated like drugs, and there’s no guarantee of what you’re buying, said Glatt, who is also chief of infectious diseases at Mount Sinai South Nassau in Oceanside, NY.

Beyond that, most people wouldn’t need to take a probiotic just to eliminate any stray S. aureus in the body.

Otto said the potential application would be to prevent S. aureus infections in certain high-risk people, such as those who have had recurrent infections in the past or patients on kidney dialysis.

The probiotic doesn’t actually “kill” S. aureus, Otto noted, but rather inhibits its ability to establish a colony. It would therefore not treat an established staph infection.

Why do some people carry a healthy supply of Bacillus? It’s not entirely clear, but Otto noted that the 2018 study was also conducted in rural Thailand, where many people may have ingested the bacteria from plant foods that weren’t washed. (The bacillus is abundant in soil.)

But Otto said he wouldn’t advocate eating unwashed fruits and vegetables in hopes of replenishing Bacillus.

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