The mobile FOX AmpC beta-lactamases originated in Aeromonas allosaccharophila
Journal article, 2019

Objective: It is important to understand the origins of antibiotic resistance genes so that risks associated with the emergence of novel resistance genes can be assessed and managed. The chromosomal ampC gene (CAV-1) of Aeromonas caviae (A. caviae) has been reported as the origin of mobile FOX cephalosporinases. The recent identification of A. caviae as the origin of MOX-2 cephalosporinases and the comparably great sequence divergence between FOX and MOX genes makes it unlikely that both genes arose from the same species. Therefore, this study investigated the origin of FOX cephalosporinases using large-scale genomics. Methods: Publicly available genomes and plasmids were searched for FOX-like genes. Synteny and nucleotide identities of the identified FOX-like genes and their genetic environments were compared and a phylogenetic tree was generated. Results: FOX-like genes were identified in > 230 Aeromonas genomes and in 46 Enterobacteriaceae isolates. Analysis of the genomic context of CAV-1 revealed a truncated insertion sequence directly upstream of the ampC gene. The chromosomal ampCs of A. caviae (n = 31) were 75–78% identical to CAV-1. In contrast, CAV-1, mobile FOX genes and their context were 95–98% similar to the chromosomal ampC-locus of Aeromonas allosaccharophila (A. allosaccharophila) (n = 6). The A. allosaccharophila ampCs formed a monophyletic branch with mobile FOX genes, whereas the A. caviae ampCs clustered with mobile MOX genes. Conclusions: These findings show that FOX cephalosporinases originate not in A. caviae, as previously reported, but in A. allosaccharophila, which is a fish pathogen. This finding agrees with the hypothesis that antibiotic use in aquaculture could have contributed to the emergence of FOX genes in human pathogens.

FOX

AmpC

Aeromonas

Antibiotic resistance

Author

Stefan Ebmeyer

Center for Antibiotic Resistance Research

University of Gothenburg

Erik Kristiansson

Chalmers, Mathematical Sciences, Applied Mathematics and Statistics

Center for Antibiotic Resistance Research

D. G. Joakim Larsson

Center for Antibiotic Resistance Research

University of Gothenburg

International Journal of Antimicrobial Agents

0924-8579 (ISSN)

Vol. 54 6 798-802

Subject Categories

Evolutionary Biology

Bioinformatics and Systems Biology

Genetics

DOI

10.1016/j.ijantimicag.2019.09.017

PubMed

31600552

More information

Latest update

12/13/2019