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

Abstract

Members of the genus Aeromonas are 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 identify Aeromonas species within Lake Erie, determine their antibiotic resistance patterns, and assess their potential pathogenicity. Aeromonas strains were isolated from Lake Erie water by use of Aeromonas selective 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 on gyrB gene sequences. A molecular virulence profile was identified for each isolate, using multiplex PCR analysis of six virulence genes. We demonstrated that Aeromonas comprised 16% of all culturable bacteria from Lake Erie. Among 119 Aeromonas isolates, six species were identified, though only two species (Aeromonas hydrophila and A. veronii) predominated among tetracycline-and ciprofloxacin-resistant isolates. Additionally, both of these species demonstrated pathogenic phenotypes in vitro. Virulence gene profiles demonstrated a high prevalence of aerolysin and serine protease genes among A. hydrophila and A. veronii isolates, 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.

Functional Genomic Characterization of Virulence Factors from Necrotizing Fasciitis-Causing Strains of Aeromonas hydrophila

“…We believe that since these water samples were collected at a later time subsequent to the infection of the patient, water microbiota changed because of fluctuations in the environmental conditions (85,86). Nevertheless, our studies reinforce the idea that both benign and highly virulent strains can be present at all times in fresh and brackish waters, where aeromonads flourish.…”

“…Importantly, the prevalence of aerolysin and serine protease-encoding genes and their corresponding hemolytic and proteolytic/cytotoxic activities was also high in antibiotic-resistant strains of some Aeromonas species (e.g., A. hydrophila and A. veronii), suggesting that they contribute to bacterial virulence (85). Since the antibiotics of choice for the treatment of aeromonads are sulfamethoxazole-trimethoprim and ciprofloxacin (87), the presence of antibiotic-resistant Aeromonas strains in natural water becomes even more significant in the management of serious infections such as NF.…”

Detection and diversity of aeromonads from treated wastewater and fish inhabiting effluent and downstream waters

“…Aeromonas species have received increased attention due to their association to human diseases and conditions (Skwor et al, 2014). As contact-borne, A. hydrophyila, A. sobria, and A. caviae may cause fish handler disease through skin wound infections and systemic infections, while as food-borne, A. hydrophyila may lead to gastroenteritis, diarrhea and systemic infections (Austin and Austin, 1999;Goni-Urriza et al, 2000;Lehane and Rawlin, 2000;Huddleston et al, 2006;Cabello et al, 2013).…”

“…Members of the genus Aeromonas are symbionts of zebrafish, leeches, and dreissenid mussels (Skwor et al, 2014). Aeromonads have been associated with bacterial zoonoses and fish diseases (Austin and Austin, 1999), and recovered from urban sewage and rivers with sewage pollution (Vandewalle et al, 2012).…”

Identification of New Natural CphA Metallo-β-Lactamases CphA4 and CphA5 in Aeromonas veronii and Aeromonas hydrophila Isolates from Municipal Sewage in Central Italy

“…Members of the genus Aeromonas have developed a high level of resistance to antibiotics, in particular to ␤-lactams and fluoroquinolones (2,3). Several classes of ␤-lactamases are identified in Aeromonas spp., even though metallo-␤-lactamases (MBLs), which belong to class B, are the usually identified most often (4,5).…”