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Science: Antibiotic can also protect bacteria instead of fighting them


Antibiotic protects bacteria from acid attacks
Antibiotics are intended as drugs against bacteria and usually have a very convincing effect on bacterial infections. However, the increasing resistance of the pathogens cause problems during use. Now a team of researchers from the Institute of Science and Technology Austria (IST Austria) has found that antibiotics can also increase the chances of bacteria surviving under certain conditions.

According to the Austrian researchers, the stress reaction in the bacteria when using antibiotics can result in improved acid resistance. For example, the stress caused by the antibiotic trimethoprim (TMP) may result in improved protection of the bacteria against acid attacks, the scientists report of their study results. These were published in the specialist magazine "Cell Systems".

Stress reactions offer protection
According to the researchers, the antibiotic TMP inhibits the growth of the bacterium Escherichia coli, which triggers a stress reaction in the bacteria. First author Karin Mitosch, together with Georg Rieckh and Tobias Bollenbach from the Institute of Science and Technology Austria, investigated to what extent the stress reaction also protects the bacteria against other influences. A specific stress reaction can help bacteria to survive other attacks from the outside - such as gastric acid - better.

Cross protection an underestimated problem?
The bacteria are often exposed to inhospitable conditions, to which they respond with corresponding stress reactions, the scientists explain. Such reactions to a certain stress factor can also protect the bacterium against another stressor; the researchers continued. In this case, one speaks of a so-called cross protection. Here the question arose whether the reaction to antibiotics could offer such cross protection. The experts explain that antibiotics activate genes that are responsible for the stress reaction.

Antibiotic TMP particularly critical
So far it was unclear whether the stress reaction can also protect the bacteria against other environmental influences. To investigate this, the researchers observed the reaction of Escherichia coli to four different antibiotics. She also analyzed how the transcription changes in response to the antibiotics in the entire genome of the bacterium.

The transcription is the translation of DNA into mRNA, which in turn provides the instructions for the construction of proteins, the scientists explain. With the antibiotic TMP, a quick acid-stress reaction was shown, which was very different from bacterial cell to bacterial cell.

Bacteria protected from acid attacks
“Those bacterial cells with a strong stress reaction are then better protected against an acid attack,” the researchers explain the result of their investigation. If the bacterial populations were exposed to an extremely acidic hydrochloric acid solution, they died rapidly, whereby the period of survival - like the decay of radioactive substances - was measured as a “half-life”. This is usually just under 30 minutes. However, the Austrian researchers report that if the bacterial population was first placed in a solution with TMP and some time later in the hydrogen chloride solution, the half-life tripled to over 100 minutes.

Biochemical mechanism of cross protection decoded
The scientists were able to determine exactly which biochemical mechanism this cross protection is based on. “TMP leads to a reduction in adenine nucleotides, an important building block of DNA and the cell's energy source. This reduction in turn triggers the stress response against acids, ”write Mitosch and colleagues.

According to their own information, they provided with their study instructions on how to find the cross protection between antibiotics and other stressors. "This is important because our study provides an example of how antibiotics affect the chances of survival of bacteria in different environmental conditions," Mitosch continued. If an existing cross protection is known, according to the expert, "targeted strategies could be developed that increase the effectiveness of antibiotics in the treatment of diseases." (Fp)

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Video: Exploding bacteria with penicillin (December 2021).