Virulence markers in Aeromonas hydrophila and Aeromonas veronii biovar sobria isolates from freshwater fish and from a diarrhoea case

Abstract

Aims: To evaluate the public health significance of representative strains of two Aeromonas spp., mainly from freshwater fish, on the basis of production of virulence-associated factors and presence of the haemolytic genes aerA and hlyA. Methods and Results: Eleven strains of Aer. hydrophila, three strains of Aer. veronii biovar sobria (all from freshwater fish) and one strain of Aer. hydrophila from human diarrhoea were tested for potential virulence traits and for the presence of the haemolytic genes aerA and hlyA. Ten Aer. hydrophila isolates were aerA + hlyA + and two aerA + hlyA -. Aeromonas veronii biovar sobria isolates were aerA -hlyA -. Strains from the three genotypes showed enterotoxic activity in the suckling mouse assay. At 28°C, four Aer. hydrophila fish strains could be considered as potentially virulent (possessing at least two of these characteristics: haemolytic, cytotoxic and enterotoxic). One Aer. veronii biovar sobria strain and the clinical isolate were cytotoxic on Vero cells. When grown at 4°C, these six isolates fulfilled virulence criterion, but at 37°C, only one fish strain, an Aer. hydrophila, did. Conclusions: The potential health risk derived from the presence of Aer. hydrophila and Aer. veronii biovar sobria in ice-stored freshwater fish should not be underestimated. Significance and Impact of the Study: Expression of virulence factors is affected by temperature incubation and not always related to the presence of haemolytic genes.

Detection of putative virulence genes in Aeromonas isolates from humans and animals

“…It has been reported that the aerA + /hlyA + genotype provided the best estimation of virulence for A. hydrophila in an animal model [31]. However, a study found that, when the distribution of hemolytic genes was compared to extracellular products, three genotypes (aerA + /hlyA + , aerA + /hlyA -, aerA -/hlyA -) were enterotoxic in the suckling-mouse test and had a capacity to express other virulence properties at different temperatures [32]. Pablos et al [13] In the current study, the virulence gene was not detected in 43.75% of human isolates and in 33.3% of animal isolates (in all cattle and sheep isolates).…”

Draft Genome Sequence of an Aeromonas sp. Strain 159 Clinical Isolate That Shows Quorum-Sensing Activity

“…Aeromonas spp. pose a threat to public health due to the emergence of antibiotic-resistant strains (4). In this study, the clinical Aeromonas sp.…”

Molecular Characterization of Fluoroquinolone-Resistant Aeromonas spp. Isolated from Imported Shrimp

“…Copious amounts of antibiotics are used in the shrimp ponds to stimulate growth and to retard the incidence of diseases caused by overcrowded, factory farm conditions (4, 5, 9). The indiscriminate use of these antibiotics may select bacteria resistant to multiple antibiotics, and such bacteria may transfer their antibiotic resistance determinants to pathogenic bacteria (14,16).Aeromonads are ubiquitous, psychrophilic, Gram-negative microbes commonly found in fresh water, estuaries, and other coastal waters (6,7,8). They are known to cause hemorrhagic septicemia in aquatic organisms.…”

“…Aeromonads are ubiquitous, psychrophilic, Gram-negative microbes commonly found in fresh water, estuaries, and other coastal waters (6,7,8). They are known to cause hemorrhagic septicemia in aquatic organisms.…”

“…Chacon et al (6) indicated that 65.0% of the aeromonads isolated from clinical and environmental samples harbored the aer and act genes. All freshwater fish isolates of A. hydrophila harbor the aer gene, but strains of A. veronii do not contain the gene (8). However, Nawaz et al (17) reported that template DNA from 96.0% of the A. veronii strains isolated from catfish harbored the putative aerolysin gene.…”