A recent collaborative study at Forsyth Institute and Texas Tech University has proven the effect of using a harmless bacteria species to protect humans from life-threatening MRSA infections. The study shows how the nonmalignant strain Corynebacterium interacts with the Staphylococcus aureus (S.aureus) strain that causes the MRSA infection by inhibiting the harmful bacteria. Furthermore, researchers have found that the interactions between S. aureus and other benign, ingrown human bacteria can lead to new treatments for other diseases.
The study was led by Dr. Katherine Lemon and Matthew M. Ramsey PhD, from Forsyth Institute and Kendra Rumbaugh from Texas Tech University. The full study is titled “Staphylococcus aureus shifts towards commensalism in response to Corynebacterium species.” It is published in the Frontiers in Microbiology website.
In particular, the researchers focused on S. aureus that grows in nostrils, causing a risk for infection. Over a quarter of the U.S. population is exposed to this S. aureus bacteria without ever getting sick, but the presence of the bacteria does at times cause infections ranging from mild skin irritation to life-threatening MRSA.
“Our research helps set the stage for the development of small molecules and, potentially, probiotic therapies for promoting health by actively managing nasal microbiome composition,” Dr. Lemon said in a press release. “This research identifies a role for Corynebacterium species in suppressing S. aureus virulence.”
To determine the beneficial relationship between the two studied bacteria, Dr. Lemon and her team looked for changes in the S. aureus gene expression during coculture with the Corynebacterium species. It was found that the Corynebacterium species caused a decrease in transcription of the harmless S. aureus genes. Furthermore, many of the S. aureus quorum signal accessory systems were strongly inhibited in response to the harmless strand. The evidence proved a shift to a commensal state rather than a virulent state. The S. aureus can cause a broad array of colonization and virulence factors to interact with a host. Humans can be subjected to degraded enzymes and immune evasion machinery if exposed.
Dr. Lemon and the other researchers chose to work with the S. aureus strain because an antibiotic resistant form of the bacteria has recently been discovered. Methicillin-resistance S. aureus, more commonly known as MRSA, has caused over 80,000 cases of invasive disease and over 10,000 annual deaths from 2005 through 2011, according to the Centers for Disease Control and Prevention.
This particular antibiotic resistant strain may foreshadow the emergence of other antibiotic resistant bacteria, so Dr. Lemon and her team are working towards finding other interactions between potentially helpful and harmful bacteria in the human microbiome in order to find novel methods of treating disease.
“We look forward to an increase in research on commensal-pathobiont interactions within the human microbiome and an ever-increasing understanding of the significance of our beneficial bacteria partners,” Dr. Lemon, the head researcher, said in a press release.
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