How bacteria become resistant to antibiotics

Antibiotic resistance means that bacteria can survive antibiotic treatment. Linus Sandegren, Associate Professor and Senior Lecturer in Medical Bacteriology, studies bacterial evolution with a strong focus on how bacteria become resistant to antibiotics and how resistance genes can spread between different bacteria with so-called horizontal gene transfer.

“Most of the resistance genes that we find in bacteria in hospitals today do not have their actual origin in those bacteria, but usually in completely harmless bacteria from soil or water enviroments,” says Sandegren. "These bacteria lived together with the microorganisms that originally produced various natural antibiotics and from which we have developed our clinical antibiotics.”

The problem is that bacteria can share genes with each other and the genes that were originally protective for bacteria in their natural environment have now moved to infectious bacteria and given them an advantage in hospital settings.

"These mechanisms are the reason why we now have problems with resistance to all the antibiotics available today," explains Sandegren. “The bacteria have been able to combine them so that we get so-called multi-resistant bacteria that in some cases are resistant to all different antibiotics at once. The bacteria have managed this evolution in just the 80 years that we have been using antibiotics.”

New approaches to genetic changes

Today, research shows that the same evolutionary mechanisms create resistance to current antibiotics over and over again. For the future, there is hope for research studies that can show how we can make it more difficult for bacteria to become resistant to future antibiotics.

“As new methods have been developed in recent years, our ability to do large-scale genome sequencing is increasing, revealing the evolutionary changes in bacteria.  Better methods for making genetic changes in the bacterial genome in the lab allow us to experimentally test hypotheses in ways that were not possible before.”

Resistance dynamics past, present and future

At this year's Göran Gustafsson symposium, Linus Sandegren will talk about the dynamics of resistance in the past, present and the future, and explain the historical view of the emergence of resistance to, for example, penicillin.

“Today we know bacteria develop and spread resistance in ways that we did not think possible before,” says Linus Sandegren. "I will then make a prediction about what we need to think about regarding the ability of bacteria to develop and spread resistance mechanisms for future new antibiotics.”

At the symposium, the audience will learn about a wide range of antibiotic resistance research. Research that is needed to improve the situation in society around antibiotic resistance.

“Usually, antibiotic resistance is mostly thought of as a medical problem. But the causes are multifactorial and very closely linked to human behaviour, industrial use of antibacterial substances outside medicine, and also the economic systems that govern drug research”

“In addition, socio-economic factors such as access to clean water, adequate food and healthcare are important for infectious diseases. We need more research in many different scientific disciplines to address the problems of antibiotic resistance," concludes Sandegren.