Spread of Pseudomonas Aeruginosa: Harmless Bacteria

In just two centuries, Pseudomonas aeruginosa bacteria have transformed from harmless microbes into one of the greatest infectious threats on the planet. Responsible for more than 500,000 deaths a year, the bacteria are now blacklisted by the World Health Organization (WHO) as high-priority pathogens due to their antibiotic resistance and widespread global distribution, according to a recent study published in the journal Science.

The study, led by Andres Floto, professor of respiratory biology at the University of Cambridge, mapped the genomic pathway of these bacteria and revealed how they exploit immunological defects in cystic fibrosis patients to survive and proliferate. “Some individual bacteria, which we call clones, have picked up new genes and become more capable of infecting people, spreading around the world,” explains Floto.

The study identified 21 epidemic clones responsible for more than 50% of all P. aeruginosa infections worldwide. The bacteria have expanded significantly since the late 18th century, coinciding with increased industrialization and migration to cities, factors that created an ideal environment for their spread due to overcrowding and increased pollution.

P. aeruginosa has now become an opportunistic pathogen, causing pulmonary and systemic infections in people with weakened immune systems, such as those with COPD or cystic fibrosis. These infections occur in both hospitals and community settings, and their ability to adapt to multiple ecosystems and antibiotic resistance are alarming, says Bruno González-Zorn of the Complutense University of Madrid and a WHO adviser.

Bacterial clones

The study highlights the evolution and specialization of these bacterial clones, which have been specifically adapted to infect the lungs of patients with or without cystic fibrosis, but not both. This suggests a specialization that could make transmission between different types of patients more difficult.

Experts such as María del Mar Tomas from the University Hospital Complex of A Coruña highlight the importance of this research for better understanding the mechanisms of bacterial resistance and the development of new treatments. Knowing the evolutionary trajectory of P. aeruginosa and its disease emergence strategies could help develop more effective methods of containing these infections.

Floto and his colleagues emphasize the need for global surveillance and prevention of cross-contamination to prevent the emergence of new epidemic clones. The speed with which these clones appear highlights the need to detect and destroy them before they spread further. @mundiario

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