Characterization of virulence and antimicrobial resistance genes of Aeromonas media strain SD/21–15 from marine sediments in comparison with other Aeromonas spp.

Abstract

<i>Aeromonas media</i> is a Gram-negative bacterium ubiquitously found in aquatic environments. It is a foodborne pathogen associated with diarrhea in humans and skin ulceration in fish. In this study, we used whole genome sequencing to profile all antimicrobial resistance (AMR) and virulence genes found in <i>A</i>. <i>media</i> strain SD/21-15 isolated from marine sediments in Denmark. To gain a better understanding of virulence and AMR genes found in several <i>A</i>. <i>media</i> strains, we included 24 whole genomes retrieved from the public databanks whose isolates originate from different host species and environmental samples from Asia, Europe, and North America. We also compared the virulence genes of strain SD/21-15 with <i>A</i>. <i>hydrophila</i>, <i>A</i>. <i>veronii</i>, and <i>A</i>. <i>salmonicida</i> reference strains. We detected <i>Msh</i> pili, tap IV pili, and lateral flagella genes responsible for expression of motility and adherence proteins in all isolates. We also found <i>hylA</i>, <i>hylIII</i>, and <i>TSH</i> hemolysin genes in all isolates responsible for virulence in all isolates while the <i>aerA</i> gene was not detected in all <i>A</i>. <i>media</i> isolates but was present in <i>A</i>. <i>hydrophila, A</i>. <i>veronii</i>, and <i>A</i>. <i>salmonicida</i> reference strains. In addition, we detected <i>LuxS</i> and <i>mshA-Q</i> responsible for quorum sensing and biofilm formation as well as the ferric uptake regulator (<i>Fur</i>), heme and siderophore genes responsible for iron acquisition in all <i>A</i>. <i>media</i> isolates. As for the secretory systems, we found all genes that form the T2SS in all isolates while only the <i>vgrG1</i>, <i>vrgG3</i>, <i>hcp</i>, and <i>ats</i> genes that form parts of the T6SS were detected in some isolates. Presence of <i>bla</i> _MOX-9 and <i>bla</i> _OXA-427 β-lactamases as well as <i>crp</i> and <i>mcr</i> genes in all isolates is suggestive that these genes were intrinsically encoded in the genomes of all <i>A</i>. <i>media</i> isolates. Finally, the presence of various transposases, integrases, recombinases, virulence, and AMR genes in the plasmids examined in this study is suggestive that <i>A</i>. <i>media</i> has the potential to transfer virulence and AMR genes to other bacteria. Overall, we anticipate these data will pave way for further studies on virulence mechanisms and the role of <i>A</i>. <i>media</i> in the spread of AMR genes.