Researchers discover a previously unknown mechanism in bacteria.
Antibiotic resistance is one of the major problems of medicine, which is constantly increasing. If bacteria no longer respond to these substances, the infections they cause can no longer be effectively controlled. Until now, the hypothesis was that resistant pathogens spread especially when many antibiotics were used. Scientists from the Swiss Federal Institute of Technology Zurich (ETH), the University of Basel and the Swedish University of Uppsala challenge this shared vision as the only explanation. During laboratory experiments on Salmonella, they discovered a mechanism until then unknown for the propagation of resistance. This has to do with "dormant" bacteria and exists regardless of the use of antibiotics.
The researchers conclude that limiting the use of these drugs will not be enough to stop the resistance. Their conclusions were published in the journal "Nature".
It is known that bacteria can "inherit" their insensitivity to antibiotics via certain genes of resistance to other populations. According to Darwin's theory of evolution, it was assumed that resistant pathogens would have an advantage over other germs only if antibiotics were present in the environment. This is why experts advocate a more economical prescription of these drugs. The Swiss-Swedish research team does not deny that this approach makes sense, but it is not enough. For this, one must start with the resistant microorganisms themselves, says Mederic Diard of the Biozentrum of the University of Basel, who led the study with Wolf-Dietrich Hardt of the ETH's Zurich. It must be ensured that these germs can not spread "for example by hygiene measures or more effective vaccinations".
Persistent bacteria, called Persistent, play a central role in the recently discovered distribution mechanism. These are bacteria that fall into a temporary state of twilight and can reduce their metabolism to a minimum. As a result, they can no longer be killed by antibiotics.
The researchers found that these "dormant forms" are formed in Salmonella when bacteria enter the body's tissues from the intestine. In the tissue, persistent patients can then spend several months in a discrete existence to wake up in favorable conditions and cause a new outbreak of infection.
The researchers also found that salmonella often combined the two resistance mechanisms. Thus, Persisters often carry a small genetic material containing resistance genes.
In experiments on mice, scientists have discovered that sleepers are able to transmit resistance to other clean organisms or even alien species – such as E. coli bacteria of the normal intestinal flora. This happens whether antibiotics are involved or not.
According to the researchers, the results obtained from the murine model should be examined at the next stage in livestock, for example in pigs frequently suffering from Salmonella infections. In addition, it should be investigated whether the spread of Salmonella resistance can be reduced by the administration of probiotics or a vaccine.