Tip of the iceberg
76 new antibiotic resistance genes found in bacteria
After analyzing the genomes of bacteria from around the world, microbiologists from the University of Gothenburg in Sweden have discovered a number of previously unknown genes responsible for resistance to strong antibiotics carbapenems.
Carbapenems are a class of broad–spectrum antibiotics often used against polyresistant strains of bacteria that are not affected by a number of other drugs. Nevertheless, some particularly aggressive bacteria have learned to cope with carbapenes with the help of the enzyme B1-metallo-β-lactamase, which is able to degrade the antibiotic. The genes responsible for this type of resistance can be difficult to detect, because they are often located on mobile genetic elements – DNA sequences that can move inside the genome. In a new study, scientists have proposed an approach to bacterial DNA analysis that effectively predicts new genes encoding B1-metallo-β-lactamase.
The algorithm developed by scientists is based on the use of so-called hidden Markov models. With their help, the algorithm determined DNA sequence patterns by examining already known carbapenem resistance genes. Then, examining any DNA sequence, the algorithm assigned it a certain score – the probability that the B1 metallo-β-lactamase gene was also encoded in it. Genes with a value above the threshold were considered potential targets for further research by scientists.
After analyzing more than 10,000 bacterial genomes from around the world, scientists have identified 76 previously unknown candidate genes. To test the effectiveness of prediction, the authors synthesized some of them and introduced Escherichia coli into Escherichia coli. The experiment showed that 18 of the 21 genes turned out to be functional, which indicates the high accuracy of the prediction algorithm. Thus, the researchers increased the number of known B1 metallo-β-lactamase genes by more than two times.
The authors of the article call the result of their work "the tip of the iceberg", which shows how many types of antibiotic resistance that have not yet been studied exist. In the future, scientists also plan to develop algorithms to detect genes for resistance to other types of antibiotics. By knowing more about how bacteria resist treatment, we will be able to deal more effectively with polyresistant bacteria, the researchers say.
An article describing the results of the work was published in the journal Microbiome.
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