before the eighteenthH century, Pseudomonas aeruginosa Once a harmless bacterium that lived in ponds, streams and on plants, today this pathogen kills 500,000 people a year and is considered a top priority by the World Health Organization. He explained in July Journalist Jessica Mozzo at the newspaper The pays.
study Published in the magazine sciences It allowed scientists to go back in time and reconstruct the evolution of P. aeruginosa Over the past 200 years, nearly 10,000 samples of these bacteria from humans, animals, and the environment have been analyzed.
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This work allowed them to discover the presence of certain bacteria during these two centuries. P. aeruginosa They have managed to acquire new genes to infect humans. The researchers call these “improved” versions of the pandemic clones.
Thus, scientists have identified 21. The first probably appeared around 1890. Between 1900 and 1950, six new clones appeared, and then another 12 between 1950 and 2000. Each of them had a period of expansion, meaning a moment of rapid reproduction and spread around the world.
The increased frequency of these expansion events can be partly explained by air pollution: researchers believe this increases susceptibility to infection. Population growth in some cities and migration movements have also contributed to the spread of pandemic clones, and have contributed to epidemics since the 20th century. Today, the 21 identified clones are thought to be responsible for half of all infections caused by P. aeruginosa.
Danger to patients
Bacteria P.Angularia So it becomes what we call an opportunistic bacteria, meaning it doesn't infect healthy people, but it can cause infections in those whose immune systems are weakened. This is especially the case for people with cystic fibrosis.
Researchers have even identified clones that only circulate among patients with the disease. They actually have genes that allow them to survive the attack of those patients' own defective macrophages.
bacteria P. aeruginosa It also has an “exceptional ability” to adapt to different environments, as one expert put it. The paysThe expert, who was not involved in the study, said: “The pandemic clones are therefore at risk of becoming increasingly resistant to antibiotics. The results of this study could help scientists better understand the mechanisms behind this evolution and perhaps develop ways to combat it.”
