Bovine bacteria may fight deadly MRSA infection

Scientists have found that bacteria commonly found in dairy cows produce signaling molecules that can effectively treat antibiotic-resistant infections, providing promising weapons to combat the growing threat of methicillin-resistant Staphylococcus aureus (MRSA).

The discovery could help solve one of the most pressing challenges in medicine: bacterial infections that no longer respond to traditional antibiotics.

Researchers at the University of Copenhagen have made the largest mapping of dates on bacterial communication networks, revealing how different staphylococci species interfere with each other’s ability to attack human tissue. Their work identified signaling molecules from Staphylococcus (a species commonly found on cattle) that could effectively disrupt MRSA’s communication systems as efficiently as standard antibiotic treatments.

Bacterial Communication Network

Like people talking about intercoms, bacteria also communicate with specific “frequency” or signal molecules to coordinate group behavior. When pathogenic bacteria, such as MRSA, infect wounds, they use these chemical signals to organize their attacks. However, other bacterial species can block these communications, thereby weakening the pathogen’s ability to cause disease.

“By our mapping, we can determine which signaling molecules are most effective for MRSA,” said Christian Adam Olsen, professor in the Department of Drug Design and Pharmacology at the University of Copenhagen. “We found that signaling simulans from another staphylococci variant were very effective for Staphylococcus aureus. Initially, signaling molecules were isolated from bacterial strains from bovine, but also on goats, horses and humans.”

The team tested 35 different signaling molecules from 21 bacterial species and created a comprehensive map of 280 bacterial interactions. They found that molecules from animal-related bacteria are generally more effective than molecules from human-related species.

Testing MRSA

The researchers tested their most promising candidates. Simulans signaling molecules – laboratory and animal research. Key findings include:

• Single dose matches the effectiveness of mouse daily antibiotic ointment
• After 15 days of exposure, the bacteria showed no signs of resistance
• Treatment reduces the bacterial load on infected skin by about 60 times
• Signaling molecules can deactivate already active MRSA infection

In the mouse study, animals treated with S. simulans signaling molecules had significantly reduced skin lesions after 48 and 96 hours compared to untreated controls. This treatment is carried out with a molten acid equivalent to a standard antibiotic ointment.

“In the experiment, we showed that using a single dose of this signaling molecule, mice could overcome MRSA skin infections as effectively as mice treated with antibiotic ointments every day,” in the study contributed to the study.

Avoid resistance to development

Unlike antibiotics that kill bacteria and create resistance, these signaling molecules work by disrupting communication without being lethal. Bacteria can survive, but lose the ability to coordinate attacks on the host’s immune system.

“As we saw in the use of antibiotics, no one has tested whether Staphylococcus has been resistant to treatments using these signaling molecules,” Sereika-Bejder explained. “In our experiments, we observed that under laboratory conditions, the bacteria did not develop even after 15 days.”

This mechanism has a crucial advantage over traditional antibiotics. Since signaling molecules do not kill bacteria, the evolutionary pressure to drive resistance development is less. Bacteria naturally encounter similar molecules in the environment, making resistance less likely.

Clinical potential

This study published in MBIO represents an important step in developing antiviral therapies, a treatment that removes pathogens rather than kills them. This approach is particularly valuable for the treatment of MRSA infections, which affect hundreds of thousands of people each year and resist many standard antibiotics.

The Copenhagen team used complex techniques, including natural chemical ligation, to identify and synthesize bacterial signaling molecules. Their systematic approach shows that the bacteria associated with bovine produce some of the most potent inhibitors, while the S. simulans molecule shows 400 times less potent than previously known inhibitors.

Early clinical studies with similar bacterial communication inhibitors have shown promise in the treatment of skin conditions such as atopic dermatitis. The researchers believe their findings may lead to treatments that work with existing antibiotics, or as alternatives when resistance develops.

While the initial results focus on skin infections, the underlying principles may possibly address other MRSA-related diseases. This study opens up the possibility for developing treatments by disrupting bacterial teamwork rather than a competition for weapons that rapidly evolved with pathogens.

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