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

Abstract

Aeromonas media 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 A. media strain SD/21–15 isolated from marine sediments in Denmark. To gain a better understanding of virulence and AMR genes found in several A. media 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 A. hydrophila, A. veronii, and A. salmonicida reference strains. We detected Msh pili, tap IV pili, and lateral flagella genes responsible for expression of motility and adherence proteins in all isolates. We also found hylA, hylIII, and TSH hemolysin genes in all isolates responsible for virulence in all isolates while the aerA gene was not detected in all A. media isolates but was present in A. hydrophila, A. veronii, and A. salmonicida reference strains. In addition, we detected LuxS and mshA-Q responsible for quorum sensing and biofilm formation as well as the ferric uptake regulator (Fur), heme and siderophore genes responsible for iron acquisition in all A. media isolates. As for the secretory systems, we found all genes that form the T2SS in all isolates while only the vgrG1, vrgG3, hcp, and ats genes that form parts of the T6SS were detected in some isolates. Presence of blaMOX-9 and blaOXA-427 β-lactamases as well as crp and mcr genes in all isolates is suggestive that these genes were intrinsically encoded in the genomes of all A. media isolates. Finally, the presence of various transposases, integrases, recombinases, virulence, and AMR genes in the plasmids examined in this study is suggestive that A. media 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 A. media in the spread of AMR genes.

The mobile gene cassette carrying tetracycline resistance genes in Aeromonas veronii strain Ah5S-24 isolated from catfish pond sediments shows similarity with a cassette found in other environmental and foodborne bacteria

“…Other AMR genes detected included the cphA4 gene known to be intrinsically encoded in various Aeromonas spp. ( Dubey et al, 2022a , b ) as well as the colistin-resistance mcr-7.1 gene also reported from different Aeromonas spp. ( Dubey et al, 2022a , b ).…”

“…( Dubey et al, 2022a , b ) as well as the colistin-resistance mcr-7.1 gene also reported from different Aeromonas spp. ( Dubey et al, 2022a , b ). Despite so, the bla OXA-12 , bla FOX-7 , and mcr-7.1 genes detected in strain Ah5S-24 were not associated with integrases, recombinases or transposases suggesting that these genes could not be easily transferred or acquired from other bacteria species.…”

“…Several studies have shown that Aeromonas spp. intrinsically carry various bla OXA genes in their genomes that include the bla OXA-12 gene ( Dubey et al, 2022a , b ) previously detected in A. media , A. jandaei , A. sobria , A. dhakensis, and A. hydrophila ( Dubey et al, 2022a ; Rasmussen et al, 1994 ; Alksne and Rasmussen, 1997 ; Hilt et al, 2020 ; Huang et al, 2020 ) being in line with its presence in strain Ah5S-24 while bla FOX-7 previously reported in A. media and A. allosaccharophila was also found in strain Ah5S-24 ( Ebmeyer et al, 2019 ). Other AMR genes detected included the cphA4 gene known to be intrinsically encoded in various Aeromonas spp.…”

“…The high mortalities experienced in aquaculture have led to use of antibiotics, thereby contributing to increase of antimicrobial resistance (AMR) ( Roberts et al, 2006 ). As mentioned in our previous studies ( Dubey et al, 2022a , b ), the major limitation with most studies aimed at identifying AMR genes in bacteria is that they are mostly done by PCR that only detects AMR genes based on the primers used in the assay. This poses the risk of omitting important AMR genes whose primers are not included in PCR assays.…”

Cytotoxicity and Antimicrobial Resistance of Aeromonas Strains Isolated from Fresh Produce and Irrigation Water

“…This should alert us to remain vigilant regarding the epidemiology of resistance markers in these species. If antibiotic resistance and a high degree of virulence are combined, the combination can be very dangerous [ 53 , 54 ].…”