New research has shown that Pseudomonas develops resistance much faster than usual to a common "last resort" antibiotic.

New research has shown that Pseudomonas develops resistance much faster than usual to a common “last resort” antibiotic.


A study published today in Cell reports reveals how populations of a bacterium called Pseudomonas respond to treatment with Colistin, a “last resort” antibiotic for patients who have developed multidrug-resistant infections.

Antibiotics play a key role in human health by helping to fight bacterial infections, but bacteria can develop resistance to the antibiotics that patients rely on. Antibiotic-resistant infections now cause more than a million deaths worldwide each year.

With a small number of “last resort” antibiotics available, researchers at Oxford University are studying the processes that lead to increased and decreased resistance in populations of common bacterial pathogens, which is essential to combat increased antimicrobial resistance (AMR).

Professor Craig MacLean, Department of Biology, Oxford University, said:

“Our work has shown that a gene involved in resistance to a last-minute antibiotic mutates at an incredibly high rate, allowing bacteria to rapidly develop antibiotic resistance.” “Our research suggests that, in this particular case, the selective pressures generated by the association of this gene with the immune system may have led to the evolution of an extra-fast mutation rate, which evolves rapidly to make bacteria resistant.” to antibiotics. ”

Pseudomonas is a bacterium that frequently causes lung infections in hospitalized patients. Researchers have grown more than 900 populations of Pseudomonas and treated them with Colistin. By counting the bacteria and sequencing their genome, the researchers were able to assess how quickly different populations developed antibiotic resistance and the genetic mutation that causes the resistance.

The results showed that the Pseudomonas infections quickly developed resistance to this last-ditch antibiotic, due to a gene mutating at a rate 1,000 times higher than the “normal” background mutation rate. Mutations in this gene, known as pmrB, have allowed bacteria to develop their resistance to colistin.

Researchers suggest that the reason for this rapid mutation may be that the pmrB gene is associated with the human immune system. A rapid mutation rate would help the bacterium survive by adapting to fluctuating changes in the immune system.

Although the bacteria developed their resistance to colistin at a much faster rate than expected, the research also showed a positive result. When the antibiotic was removed, the pathogens quickly lost their resistance due to the high mutation rate.

Researchers now plan to expand their study to determine what other attributes of Pseudomonas could be involved in achieving such high levels of antimicrobial resistance.

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Materials provided by Oxford University. Note: Content is subject to change in style and length.

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