Prevalence and Genetic Analysis of mcr-3 -Positive Aeromonas Species from Humans, Retail Meat, and Environmental Water Samples

Abstract

The mobile colistin resistance gene is globally disseminated in both and species, with the latter potentially serving as a reservoir for this gene. Here, we investigated the prevalence of in rectal swabs from humans, in food-producing animals and their products, and in the aquatic environment, and we investigated the genetic relationships between the -positive isolates. An enriched broth screening method was used to detect in samples, and species identification of isolates from positive samples was carried out by matrix-assisted laser desorption ionization-time of flight mass spectrometry and shotgun sequencing. All -positive isolates were subjected to antimicrobial susceptibility testing, conjugation, and whole-genome sequencing. Ten isolates, including 2 from human rectal swabs, 1 from pork, 3 from chicken meat, and 4 from the aquatic environment, were positive for , but only 2 showed resistance to colistin. In addition to the variants identified previously (the novel variants were termed to), all isolates harbored -like genes downstream of the variants. The MCR-3.13 to MCR-3.18 proteins exhibited only 89.2% to 96.1% amino acid identity to the original MCR-3 protein. Whole-genome sequence analysis indicated diversity within the genetic environments of -positive isolates and possible transmission between different sources in China and even worldwide. Close relationships between -positive and-negative isolates suggested that might be common in species, which are not inherent hosts of but may act as an important reservoir of this mobile colistin resistance gene.

Potential KPC‐2 carbapenemase reservoir of environmental Aeromonas hydrophila and Aeromonas caviae isolates from the effluent of an urban wastewater treatment plant in Japan

“…have been reported and widely isolated from humans, retail meat and environmental water (Shen et al ., ). Most of these mcr‐3‐ positive strains showed moderate susceptibility to colistin and failed in transconjugation of mcr‐3 gene variants to E. coli recipients (Shen et al ., ), consistent with our findings that mcr‐3 variants are located on a prophage. Thus, Aeromonas spp.…”

<p>A Novel Transposon, Tn<em>6518</em>, Mediated Transfer of <em>mcr-3</em> Variant in ESBL-Producing<em> Aeromonas veronii</em></p>

“…15,24 Until now, there are several mcr-3 variants, including mcr-3.3 and mcr-3.13 to mcr-3.18, identified among 10 Aeromonas isolates from different sources. 12 Shen et al reported samples from the aquatic environment had the highest prevalence (10.0%) of mcr-3-positive Aeromonas isolates, 12 which indicated that mcr-3 have been disseminated throughout various environments, the aquatic environment might be the major reservoir. For this study, it is the first case about a novel transposon, Tn6518, mediated transfer of mcr-3.6 in ESBL-producing Aeromonas veronii isolated from chicken faeces.…”

“…[7][8][9][10] Subsequently, multiple mcr-3 variants and one mcr-5 gene were identified in Aeromonas species, implying Aeromonas species plays an important role in the dissemination of mobile colistin resistance genes. [11][12][13] Among them mcr-3 was first found in Escherichia coli isolated from pig, 14 then some papers illustrated that this gene emerged in Aeromonas spp. 12 Subsequently, Ling et al study showed that mcr-3.3 and mcr-3-like have emerged in Aeromonas veronii isolated from retail chicken meat, 8 and Eichhorn et al found four Aeromonas isolates were positive for mcr-3, each of the four mcr-3 genes showed amino acid identities of 95.0-98.0% to the original mcr-3 protein.…”

“…[11][12][13] Among them mcr-3 was first found in Escherichia coli isolated from pig, 14 then some papers illustrated that this gene emerged in Aeromonas spp. 12 Subsequently, Ling et al study showed that mcr-3.3 and mcr-3-like have emerged in Aeromonas veronii isolated from retail chicken meat, 8 and Eichhorn et al found four Aeromonas isolates were positive for mcr-3, each of the four mcr-3 genes showed amino acid identities of 95.0-98.0% to the original mcr-3 protein. These variants were designated mcr-3.6 (Aeromonas allosaccharophila from golden orfe), mcr-3.7 (Aeromonas media from), mcr-3.8 (Aeromonas jandaei from koi carp) and mcr-3.9 (Aeromonas hydrophila from koi carp).…”

An Update on the Genus Aeromonas: Taxonomy, Epidemiology, and Pathogenicity

“…It was demonstrated that Aeromonas can survive at pH = 5 [14,130]. Many studies have investigated the incidence of Aeromonas in meat products [128,131,132]. Based on the sequencing of HKG like rpoD and gyrB, the most prevalent species were A. veronii, A. salmonicida, A. jandaei, A. simiae, A. hydrophila, and A. caviae [81,125].…”