Disease cause: antibiotic therapy
Antibiotic resistance occur with increasing frequency in various pathogens. They represent an enormous threat to the population, because the resistant bacteria can hardly be controlled. How can this problem get a grip? This question are scientists from the Christian-Albrechts-Universität zu Kiel (CAU) in collaboration with colleagues from the University of Exeter, England, investigated. As 23. March published in the journal PLoS Biology, are the results obtained one of the most common treatment strategies in question: the combination therapy.
Working groups led by Kiel professors Hinrich Schulenburg and Philip Rosenstiel, together with an English team led by Professor Robert Beardmore, investigated this therapeutic approach, in which two or more antibiotics are used in combination to increase efficiency. The newly published results show that this can lead to an unforeseen acceleration of the emergence of resistance.
For the study, the emergence of resistance was investigated using evolution experiments under controlled laboratory conditions. Here, germs were brought together with different antibiotics and their combination. The results were amazing: "We were completely surprised by the speed at which resistance developed," explains Schulenburg, head of the study at the CAU. The resistances occurred mainly in the forms of treatment that are currently considered to be particularly efficient, namely the combination therapies.
How does this resistance develop and why are combination therapies so vulnerable? The subsequent full genomic analysis of the germs used brought to light an unusual evolutionary mechanism: the rapid development of resistance arose from the duplication of special genome segments containing a large number of resistance genes. "That's the principle 'a lot helps a lot,'" explains Dr. Gunther Jansen, who carried out the genomic analyses. "The more resistance genes are present in the genome, the higher the resistance."
Additional mathematical calculations confirm that resistances can generally occur particularly quickly in combination therapy. "In the long term, therefore, using just one antibiotic is more efficient," concludes Beardmore, who led the study in Exeter. In established medical considerations, therapies are usually classified as efficient or inefficient using short-term experiments. "Evolution, i.e. the ability of germs to adapt, is ignored," continues Schulenburg. "This is obviously a mistake."
The working groups from Kiel and Exeter are currently expanding the experimental approach developed in order to specifically examine the efficiency of different antibiotic therapies. They hope that this will provide further information on how treatment strategies in humans can be optimized in the future.
Original publication:
"When the most potent combinations of antibiotics select for the greatest bacterial load: the smile-frown transition", Peña-Miller R, Laehnemann D, Jansen G, Fuentes-Hernandez A, Rosenstiel P, Schulenburg H, Beardmore R (2013). PLoS Biology.
Source: Kiel [ CAU ]
