Whole-Genome Sequence of Aeromonas spp. Isolated from a Dairy Farm in Central Texas

This study investigated the presence of Aeromonas spp. on a dairy farm in central Texas that employed a free-stall management system. A total of 140 samples were collected from areas of two different barns. Twenty-two presumptive Aeromonas isolates were cultured. Phenotypic analysis identified five Aeromonas spp. Twenty isolates exhibited β-lactam and one displayed tetracycline resistance. Phylogenetic analysis of the WGS data suggested only four Aeromonas spp. All isolates possessed at least one β-lactam resistance gene and one isolate possessed tet(E). No plasmids were identified from sequence alignments. Virulence genes were identified in all four Aeromonas spp. Mobility elements were identified in three of these, with the exception being A. dhakensis. Four of the transposons identified in this study have been associated with multidrug resistance in Italy, Sweden, and Singapore. There was no significant difference in the proportion of isolates from either barn. The absence of plasmids suggests mobility elements and virulence genes were localized to the chromosome. On a dairy farm of healthy cattle, these 22 Aeromonas isolates were considered normal environmental flora while illustrating the ubiquitous nature of Aeromonas spp. globally.