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Two studies from CARe unravel the origin of antibiotic resistance genes

By a comparative genomics approach, Stefan Ebmeyer, Erik Kristiansson and Joakim Larsson have identifed the bacterial species from which several beta-lactamases were transferred to a range of important pathogens.

Understanding the evolutionary history of antibiotic resistance genes that are clinical problems today may help anticipate and possibly delay the emergence of new resistance genes in the clinic. This was the rational for the CARe researchers to explore the origins of a range of mobile betalactamases. Available genomes and plasmids in public databases were analysed for the presence of resistance genes, and their DNA sequences as well as their surrounding DNA were compared. Based on how well the DNA sequences matched, as well as the order of surrounding genes and the presence or absence of genetic elements responsible for moving DNA, the recent history of these genes could be unravelled. The analysis revealed that the CMY-1/MOX-family AmpC beta-lactamases MOX-1, MOX-2 and MOX-9 were mobilized independently from three Aeromonas species. The researchers also showed that the PER extended-spectrum beta-lactamases originate from the bacterial genus Pararheinheimera. All of these bacteria are typically found in the environment, indicating the important role of the environmental reservoir for the emergence of resistance in pathogens. While Pararheinheimera has not been associated with humans or domestic animals so far, the Aeromonas species are occasionally associated with infections. The latter is in agreement with the hypothesis that they were mobilized and transferred in humans/domestic animals during an infection treated with beta-lactam antibiotics.

Links to the studies:

Ebmeyer S, Kristiansson E, Larsson DGJ. (2019). PER extended-spectrum beta-lactamases originate from Pararheinheimera spp. J Antimicrobial Agents. 53:158 https://doi.org/10.1016/j.ijantimicag.2018.10.019.

Ebmeyer S, Kristiansson E, Larsson DGJ. (2019). CMY-1/MOX-family AmpC beta-lactamases MOX-1, MOX-2 and MOX-9 were mobilized independently from three Aeromonas species. Journal of Antimicrobial Chemotherapy. https://doi.org/10.1093/jac/dkz025