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The origin of FOX beta-lactamases is a fish pathogen

CARe scientists have identified the chromosomal origin of a group of genes providing resistance to several important antibiotics. The bacterium in which these genes originated is an aquatic bacterium known to cause infections in fish.

To manage and assess risks associated with the emergence of novel antibiotic resistance genes, it is important to understand how the mobile resistance genes that cause treatment failure today ended up in clinically relevant bacteria. This was the rational for the CARe researchers to explore the origin of blaFOX genes that provide resistance to many penicillins and cephalosporins. The chromosomal origin of blaFOX genes was identified by comparing publicly available DNA sequences from bacteria. The scientist compared how well sequences from different species matched the blaFOX gene circulating in pathogens, the order of surrounding genes and also the presence or absence of genetic elements responsible for moving DNA. Their analyses revealed that the chromosome of Aeromonas allosaccharophila is the origin of the blaFOX genes. This species is commonly associated with aquatic environments and is known to cause infections in fish. The findings agree with the hypothesis that antibiotic use in aquaculture could have contributed to the emergence of blaFOX genes in several human pathogens.
Links to the study:

Ebmeyer S, Kristiansson E, Larsson DGJ. (2019). The mobile FOX AmpC beta-lactamases originated in Aeromonas allosaccharophila. International Journal of Antimicrobial Agents. In press. https://doi.org/10.1016/j.ijantimicag.2019.09.017