Tous Actualités
Suivre
Abonner Schweizerischer Nationalfonds / Fonds national suisse

Schweizerischer Nationalfonds / Fonds national suisse

How bacteria sleep through antibiotic attacks

Bern (ots)

Bacteria can survive antibiotic treatment even without antibiotic resistance by slowing down their metabolism and going into a type of deep sleep. A research team funded by the Swiss National Science Foundation reveals the changes bacteria undergo to reach this "persister" state.

Resistant bacteria evade the effects of antibiotics by becoming less susceptible, for example by breaking the drugs down. But some bacteria have another survival strategy: they withstand treatment by going into a sleep-like state that enables them to tolerate antibiotics. Once therapy is complete, the bacteria wake up and re-establish the infection. This "persister" state can result in recurrent and difficult-to-treat infections. Researchers supported by the Swiss National Science Foundation (SNSF) have gained new insights into this bacterial population, thus paving the way for effective treatments. The results appear in the journal PNAS (*).

The research team worked with the bacterium Staphylococcus aureus, which is found on the skin of many people and often causes invasive and difficult-to-treat infections. The researchers took bacteria from an infected patient and cultivated them in Petri dishes. Certain bacterial colonies turned out to be smaller than others. "This tells us that the sample contains persistent bacteria," says Annelies Zinkernagel, professor of infectious diseases at the University of Zurich and University Hospital Zurich and one of the authors of the article. "Unlike other bacteria, persistent bacteria must first 'awaken', leading to delayed growth in the nutrient medium." Detection and analysis of persistent bacteria in a patient sample are particularly interesting because most of the previous studies on persistent bacteria used bacteria that were cultivated over a prolonged period of time in the laboratory and not taken directly from a patient.

Protein atlas of persistent bacteria

To determine the conditions under which bacteria become persistent, the researchers carried out various stress tests. Stress factors include the presence of human immune cells, antibiotics or an acidic environment, as occurs with abscesses. The researchers discovered that the more extreme the stress conditions, the higher the percentage of persistent bacteria.

Using bacteria recently isolated from patients, the researchers also analysed how persistence mechanisms work. To do this, they looked at the entire set of bacterial proteins, known as the proteome. Their analysis showed that comprehensive molecular reprogramming had taken place and slowed metabolism down in persisters. However, it did not come to a complete standstill, but the bacteria rather entered a kind of deep sleep. In this way, the bacteria increased their chances of survival in a hostile environment. The researchers also observed that as soon as the environment becomes more hospitable, the persistent bacteria reverse these changes and again become infectious.

"The idea that bacteria do not halt their metabolism but slow it down and change it is not entirely new. However, it is still controversial," says Zinkernagel. "Our study confirms this idea with great precision." The current study looked primarily at persistent bacteria. "Previous experiments were based on mixed populations, and the results may thus have been biased by the other bacteria, which are usually in the majority."

New treatments on the horizon

A better understanding of these mechanisms will contribute to developing new treatments against persistent bacteria. The researchers also showed that vitamin A derivatives that target the cell membrane exhibit promising potential for combating less metabolically active bacteria. Alternatively, says Zinkernagel, "if we succeed in reactivating the growth of these bacteria, they would probably no longer be able to evade the antibiotics.

"The fight against persistent bacteria is also important in the fight against resistance, because recurrent infections must be treated with antibiotics over an extended period. This constant exposure increases the risk of developing antibiotic resistance.

(*) M. Huemer, S.Mairpady Shambat et al.: Molecular reprogramming and phenotype switching in Staphylococcus aureus lead to high antibiotic persistence and affect therapy success. PNAS (2021).

--------------------------------

Research funding in all disciplines

This research work was supported by the SNSF through the project funding scheme. Following a selection process, researchers can use these grants to carry out projects with topics and goals of their own choice.

--------------------------------

The text of this press release, a download image and further information are available on the website of the Swiss National Science Foundation.

Contact:

Prof. Dr. Annelies Zinkernagel
University Hospital Zurich
Rämistrasse 100
8091 Zurich
Phone: +41 44 255 25 41
E-mail: annelies.zinkernagel@usz.ch

Plus de actualités: Schweizerischer Nationalfonds / Fonds national suisse
Plus de actualités: Schweizerischer Nationalfonds / Fonds national suisse
  • 05.02.2021 – 08:00

    Quotas to promote gender equality in research

    Bern (ots) - Gender equality is a prime concern of the Swiss National Science Foundation. To offer additional visibilty to women in academia, it is introducing gender quotas in its evaluation bodies with immediate effect. Political equality between men and women was achieved 50 years ago when women won the right to vote. But the underrepresentation of women in academic leadership roles continues: only 23 per cent of ...

  • 20.01.2021 – 17:00

    How recruiters discriminate on employment websites

    Bern (ots) - Researchers funded by the Swiss National Science Foundation conducted a large-scale study of discrimination on an online recruitment platform. The findings showed that, depending on the occupation, both men and women suffer from discrimination, and that discrimination against foreigners depends, among other things, on the time of day. Discrimination in hiring is a major societal problem. A new analysis of ...

  • 08.01.2021 – 08:00

    Goats enjoy mental gymnastics

    Bern (ots) - A study funded by the Swiss National Science Foundation shows that goats like to earn a reward by 'working' for it, even if they can get the same reward without making any effort. This finding could benefit humane husbandry. Goats respond positively to challenges rather than just turning away. In a project funded jointly by the Swiss National Science Foundation (SNSF) and the German Research Foundation (DFG), two breeding lines - dairy goats and dwarf goats - ...