New discovery of how antibiotic resistance arises

– Heteroresistance is common among the antibiotics we use frequently, and we have demonstrated it in at least ten different classes of antibiotics. In a patient carrying heterologous bacteria who is treated with antibiotics, mortality and the risk of having to be transferred to the ICU are higher compared to susceptible bacteria. So, if heterologous resistance is a starting point, we should have much better control, says Dan Anderson, professor of medical bacteriology at Uppsala University and the main person responsible for the study.

Heterologous resistance is common in many pathogenic bacteria and can lead to a lack of effect of antibiotic treatment. This specific type of antibiotic resistance means that the majority of bacteria in a community are sensitive to antibiotics, but there is also a very small resistant subset that can grow instead under antibiotic treatment. These resistant bacteria have more gene copies than others, but this also causes them to grow more slowly.

Creates new mutations

In an extensive study published in the journal Nature Communications, researchers at Uppsala University used laboratory studies to show how bacteria can create new mutations that partially compensate for slow growth. In this way, they can act as a kind of starting point and facilitate the evolution towards stable antibiotic resistance.

– We could be wrong, but we saw the process in the laboratory. There is no reason to believe that it would be any different for the patient or animal. This is an important discovery for understanding how bacteria become resistant to antibiotics, says Dan I. Anderson.

Used at the right time

It is believed that this discovery will lead to further clinical studies and increased diagnostics in microbiology laboratories. In health care, it is important to continue to restrict the use of antibiotics to combat resistance.

– It should be used at the right time, not too much, not unnecessarily, and not for viral infections. It's important to use antibiotics in an intelligent, controlled way, so that we have time to develop new ones, says Dan I. Anderson.

The research was funded by the Wallenberg Foundation, the Swedish Research Council, and the National Institutes of Health (NIH).

Marta Grosshulth