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One of the most challenges in health sector is antibiotics resistance, it is important to understand how antibiotics resistance in bacteria starts to prevent further resistance. New research from Uppsala University shows that low concentrations of antibiotics can also cause high antibiotic resistance to develop in bacteria.
Previously, the researchers have investigated how prolonged exposure to low levels of antibiotics contributes to the development of bacterial antibiotic resistance. During a course of antibiotics, a high proportion of the antibiotic dose is excreted in the urine in unchanged, active form, and can spread into watercourses, lakes and soil in the wastewater.
Consequently, these environments may contain low levels of antibiotics. In some parts of the world, large quantities of antibiotics are used in meat production and aquaculture, where small doses of antibiotics are added to the animal feed to make the animals grow faster. This means that the bacteria in their intestines are exposed to low levels of antibiotics over long periods and these bacteria can infect people through food.
Bacteria exposed to low doses of antibiotics developed resistance to antibiotic levels that were more than a thousand times higher than the initial level to which the bacteria were subjected. Mutations in the bacterial DNA that cause resistance are of a different type than if they have been exposed to high doses. During the experiment, the bacteria eventually acquired several mutations. Each of these yielded low resistance, but together they brought about very high resistance. The mutations took place in genes that have not previously been regarded as typical resistance genes, suggesting that the number of genes capable of promoting development of resistance has been greatly underestimated.
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