Aeromonas hydrophila and Aeromonas veronii Predominate among Potentially Pathogenic Ciprofloxacin- and Tetracycline-Resistant Aeromonas Isolates from Lake Erie

Abstract

ABSTRACTMembers of the genusAeromonasare ubiquitous in nature and have increasingly been implicated in numerous diseases of humans and other animal taxa. Although some species of aeromonads are human pathogens, their presence, density, and relative abundance are rarely considered in assessing water quality. The objectives of this study were to identifyAeromonasspecies within Lake Erie, determine their antibiotic resistance patterns, and assess their potential pathogenicity.Aeromonasstrains were isolated from Lake Erie water by use ofAeromonasselective agar with and without tetracycline and ciprofloxacin. All isolates were analyzed for hemolytic ability and cytotoxicity against human epithelial cells and were identified to the species level by using 16S rRNA gene restriction fragment length polymorphisms and phylogenetic analysis based ongyrBgene sequences. A molecular virulence profile was identified for each isolate, using multiplex PCR analysis of six virulence genes. We demonstrated thatAeromonascomprised 16% of all culturable bacteria from Lake Erie. Among 119Aeromonasisolates, six species were identified, though only two species (Aeromonas hydrophilaandA. veronii) predominated among tetracycline- and ciprofloxacin-resistant isolates. Additionally, both of these species demonstrated pathogenic phenotypesin vitro. Virulence gene profiles demonstrated a high prevalence of aerolysin and serine protease genes amongA. hydrophilaandA. veroniiisolates, a genetic profile which corresponded with pathogenic phenotypes. Together, our findings demonstrate increased antibiotic resistance among potentially pathogenic strains of aeromonads, illustrating an emerging potential health concern.