A Powerful Weapon Found Against Antibiotic-Resistant Staphylococcus

Serious infections caused by bacteria of the species Staphylococcus aureus (S. aureus) are often difficult to treat because the pathogens become resistant to antimicrobial drugs. However, scientists from the University of North Carolina School of Medicine have found a way to improve the situation: they discovered how to make these dangerous bacteria more susceptible to the action of common antibiotics.

⚡ You need an urgent consultation if:

• ⚠️ The infection returns after a course of antibiotics
• ⚠️ Treatment with 2-3 different drugs is ineffective
• ⚠️ You are undergoing chemotherapy or immunosuppressive treatment
• ⚠️ Your child has a cancer diagnosis
• ⚠️ Prolonged stay in intensive care
• ⚠️ After a bone marrow or organ transplant
• ⚠️ Chronic wound infections that do not heal for months

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Delay is dangerous. Resistant Staphylococcus can lead to sepsis.

In an article published in the scientific journal Cell Chemical Biology, American researchers discussed their recent discovery. They found that molecules from the polysaccharide family – rhamnolipids – can enhance the action of aminoglycoside antibiotics, such as tobramycin, against S. aureus, including resilient strains that are otherwise difficult to overcome. According to the scientists, rhamnolipids modify the membranes of Staphylococcus aureus cells, making them more flexible and pliable, which facilitates the penetration of the antibiotic.

“There is a huge need for new – more effective – methods to combat bacteria that tolerate treatment with standard antibiotics or develop resistance to them,” says the lead author of the study, Brian Conlon, an associate professor in the Department of Microbiology and Immunology at the University of North Carolina School of Medicine. “In our search for such methods, we found that altering the permeability of bacterial cell membranes for better absorption of aminoglycosides is an extremely effective strategy in the fight against Staphylococcus aureus.”

⚡ How this is applied at Ichilov Clinic:

Our infectious disease specialists and microbiologists keep track of all the latest research and apply advanced treatment protocols:

• ✅ Combination therapy with antibiotic enhancers
• ✅ Use of drugs that alter bacterial membrane permeability
• ✅ Personalized selection of combinations based on laboratory tests
• ✅ Access to clinical trials of new treatment methods

According to the American Centers for Disease Control and Prevention, in 2017, S. aureus was responsible for nearly 120,000 cases of serious bloodstream infections in the U.S., of which 20,000 were fatal.

Standard methods for combating most strains of Staphylococcus aureus are ineffective either because the bacteria have genetically acquired resistance to certain antibiotics or because they grow in the body in a way that initially makes them less vulnerable. For example, S. aureus can adapt its metabolism to survive in low-oxygen areas – in tissues with purulent inflammation or mucus-filled lungs in people with cystic fibrosis. In such environments, the bacterial membrane becomes relatively impermeable to aminoglycoside antibiotics, such as tobramycin.

Brian Conlon and his colleagues, including the first author of the study, Lauren Radlinski, discovered two years ago that rhamnolipids significantly enhance the action of tobramycin against standard test strains of Staphylococcus aureus. These polysaccharides are small molecules produced by bacteria of the species Pseudomonas aeruginosa, known as the blue pus bacillus, and serve as their natural weapon in the competitive struggle against other microorganisms in the wild. In high doses, they perforate the cell membranes of rival bacteria.

At that time, the scientists found that rhamnolipids significantly increase the absorption of tobramycin molecules, even at low doses where they have no antibacterial action of their own. In the new study, they tested a combination of rhamnolipid and tobramycin against populations of S. aureus that are typically difficult to manage in standard clinical practice. The researchers found that the polysaccharides enhance the action of tobramycin against:

• bacteria S. aureus growing in low-oxygen areas;
• methicillin-resistant S. aureus, which represent a family of dangerous variants of Staphylococcus aureus with genetically acquired resistance to drugs;
• tobramycin-resistant strains of S. aureus isolated from patients with cystic fibrosis;
• resistant forms of S. aureus that typically have reduced susceptibility to antibiotics because they grow very slowly.

“Doses of tobramycin that usually have little or no effect on these populations of S. aureus quickly kill them in combination with rhamnolipids,” says Dr. Radlinski.

Researchers found that even at low doses, rhamnolipids can modify the membrane of Staphylococcus aureus, making it much more permeable to aminoglycoside antibiotics. Each of the drugs in this family that they tested, including tobramycin, gentamicin, amikacin, neomycin, and kanamycin, demonstrated increased effectiveness. Moreover, experiments showed that this strategy, which involves enhancing their action, works not only with S. aureus but also with some other types of bacteria, including Clostridium difficile, which is a leading cause of severe, often fatal diarrheal diseases among the elderly and hospitalized patients.

Rhamnolipids come in different types, and now scientists hope to determine whether there is an optimal type among them that will effectively combat other bacteria while being minimally or not toxic to human cells. The team also plans to study other types of molecules that serve as natural weapons of one bacterium against another to find new ways to enhance the effectiveness of existing antibiotics.

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“There are many types of bacterial interspecies interactions that can potentially affect the action of our antibiotics,” says Dr. Radlinski. “We aim to find them with the sole purpose of enhancing the effectiveness of modern drugs and slowing the growth of antibiotic resistance.”