Mechanism of resistance to many bacterial drugs

In an article published in the journal Science, the team came from the University of Limoges, the French National Center for Scientific Research (CNRS), the French National Health and Medical Research Institute ( Inserm) first decodes the molecular mechanism by which bacteria resist many antibiotics, or even allow bacteria to adapt to a new environment. This new discovery highlights the difficulties faced by public health strategies when approaching drug resistance.

Antibiotic resistance appeared in the 1950s, at the same time antibiotics began to be used. Later, it was discovered that the resistance gene is easily dispersed and exchanged from bacteria to other bacteria through a system called intergrons. This system contains genes that are 'copy and paste' genes. However, the exchange and control of drug resistance remains a mystery.

The work of researchers from the Pasteur Institute collaborated with CNRS, Inserm, Medicine Department of Limoges and the Spanish team for the first time to reveal how bacteria get drug-resistant properties. It is the antibiotic that activates the synthesis of bacterial enzymes.This enzyme combines with the drug resistance gene, present in intergrons.

Staphylococcus aureus (Staphylococcus aureus) in microphotography (SEM). (Photo: Janice Haney Carr)

This enzyme also promotes the reorganization of resistance genes in intergons. The order of these genes in intergrons determines their priority level of presence: the first genes that appear the most, create the corresponding resistance to bacteria. The last genes are in a separate area and do not work. When antibiotics are introduced, new arrangements take place, for example, previously inactive genes are transferred to the first place, giving the bacteria the necessary features to fight this drug.Bacteria that have the perfect combination of genes, therefore, have a chance to survive, and ensure that resistance is maintained from generation to generation.

This work shows that the level of antibiotic adaptation is very effective both in the short and long term. This obviously poses a very difficult problem for bacterial genetics. Measures to protect public health in the future need to carefully consider this issue if they want to solve drug resistance problem thoroughly.

References:
Guerin et al.The SOS Response Controls Integron Recombination.Science, 2009;324 (5930): 1034 DOI: 10.1126 / science.1172914