A new study published in the journal Nature shows that Bacillus subtilis – a common probiotic strain in digestive supplements- helps eliminate Staphylococcus aureus, a type of bacteria that can cause serious antibiotic-resistant infections.
Staphylococcus infections cause tens of thousands of deaths worldwide each year. Methicillin-resistant Staphylococcus aureus, or MRSA, is familiar to many people as a cause of serious disease. S. aureus often can live in the nose or gut without causing any harm; however, if the tissue barrier is broken, or the immune system is compromised, these colonizing bacteria can cause life threatening infections.
In their study, the researchers recruited 200 volunteers in rural Thailand and they first analyzed fecal samples from each of the study participants for bacteria correlated with the absence of S. aureus. They found 101 samples positive for Bacillus, primarily B. subtilis— 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 probiotic Bacillus were present. 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.
P Piewngam et al. Pathogen elimination by probiotic Bacillus via signalling interference. Nature DOI: 10.1038/s41586-018-0616-y(2018).