Medicine: Antibiotic resistance: “The situation is already catastrophic”

“Infections resistant to antibiotics are responsible for more than a million deaths each year, including 250,000 children under the age of five,” explains Alexandre Persat, professor at the head of the Swiss Laboratory of Microbial Mechanics at EPFL. “For the moment, we are very poorly equipped to fight against this scourge. The situation is already catastrophic, and if we don’t find solutions quickly, it will only get worse”.

The so-called multi-resistant bacteria are the cause of many deaths during infections contracted during a stay in a healthcare establishment, called nosocomial infections. “The WHO called for the development of new drugs and specifically listed the Pseudomonas aeruginosa as a critical pathogen”, emphasizes the professor. It is precisely on this pathogen that he is carrying out research.

The Pseudomonas causes devastating infections in immunocompromised patients and individuals with cystic fibrosis and accounts for 15% of nosocomial infections. “Colistin is the antibiotic of last resort to treat these infections. It is, in some cases, already ineffective. These patients therefore no longer have any hope of recovering,” he warns.

The emergence of antibiotic resistant pathogens is a global health problem. It is influenced by many factors, such as the excessive use of antibiotics in agriculture. “Fundamental research has an important place in solving this problem, because it alone can help us identify certain Achilles’ heels of bacteria which would constitute targets for new treatments”, notes Alexandre Persat. His lab studies a once overlooked aspect of pathogens: their sense of touch.

The team demonstrated that the Pseudomonas aeruginosa becomes more virulent when it attaches to a surface. In a recent study published in The EMBO Journal, scientists have identified the precise molecular mechanisms that allow this class of bacteria to mechanically sense surfaces. “This mechanism of stimulation by contact with a surface seems to play an important role in the progression of the infection, but also in sensitivity to antibiotics, reveals Alexandre Persat.

Soft surfaces, such as those of our lungs, would thus stimulate the formation of biofilms which are breeding grounds for antibiotic resistance, as shown by the results of our research which has also been the subject of a publication in the journal of the ‘American Society for Microbiology. Thanks to these new data, we can now imagine new strategies to fight against Pseudomonas infections.”

To combat resistant pathogens, it is important to find new classes of antibiotics. But this approach is limited because, sooner or later, bacteria will evolve to become resistant and continue to be able to spread, thus creating new infections. The second approach, taken by Professor Persat, is not to kill the bacteria, but to deactivate them using a new class of molecules, called anti-virulents, which renders the pathogen unable to infect without killing it.