such as "Introduction", "Conclusion"..etc
May 28, 2009 — In an article published in Science,
teams from the Institut Pasteurand the University of Limoges,
associated with the CNRS and Inserm, decipher for the first time the
molecular mechanism that enables bacteria to acquire multi-resistance
to antibiotics, and that even allows them to adapt this resistance to
their environment. This discovery highlights the difficulties that will
have to be tackled by public health strategies if they are to address
the problems created by multi-resistance.
Multiresistance of bacteria to antibiotics is a phenomenon that
appeared when these drugs began to be used in the 1950s. It was
subsequently discovered that resistance genes were easily captured,
disseminated and exchanged from one bacterium to another by a system
involving genetic "copying and pasting" of the structures containing
these genes, known as integrons. But the dynamics of these exchanges,
which governs the multi -resistance development in bacteria, remained
The work of researchers from the Institut Pasteur associated with
the CNRS (Bacterial Genome Plasticity unit, CNRS URA 2171) and from
Inserm, within the Limoges Faculty of Medicine (EA3175, Inserm, Avenir
Team), in cooperation with Spanish teams, reveals for the first time
today how bacteria acquire these multi -resistance properties. It is
actually the antibiotics themselves that trigger the synthesis of the
bacterial enzyme that captures the resistance genes and enables their
expression in the integron.
This enzyme also promotes the random rearrangement of the resistance
genes within the integron. The order of these genes in the integron
determines the degree of priority for their expression: the first are
expressed most highly and give the bacteria the corresponding
resistance. The last remain silent, although they are kept in reserve.
When a new rearrangement occurs, triggered by taking an antibiotic, for
example, they are likely to be moved to the first positions, and give
the bacteria the required resistance to this drug. The bacteria with
the right "combination" of genes will therefore be able to survive and
ensure that the resistance potential is maintained from generation to
This work shows the extent to which strategies of bacterial
adaptation to antibiotics are effective, in both the short and the long
term. It therefore clearly demonstrates the difficulties associated
with bacterial genetics that future public health measures will have to
take into account if they are to tackle the problem of multi-resistance.
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