Distribution of Aeromonas species in environmental water used in daily life in Okinawa Prefecture, Japan

Abstract

Objectives The genus Aeromonas is known to causes diseases such as food poisoning, sepsis, and wound infection. However, the mode of Aeromonas transmission from environment to humans is not clearly understood. To evaluate the health risks of Aeromonas spp. in environmental freshwater, the number, proportion and putative virulence factors of Aeromonas species were investigated in Okinawa Prefecture, Japan. Methods Environmental freshwater samples were collected from three dams, two springs and three private wells. Aeromonas strains were identified by the biochemical method and the viable count was calculated. The production of extracellular enzymes and the virulence genes were investigated for possessing putative virulence factors using representative isolates. Results At least seven species of already-known Aeromonas isolates as well as unidentified Aeromonas spp. with/without arginin dehydrolase (ADH) exist in water at these sites. Aeromonas spp. was found to exist at over 1000 CFU/100 ml in one spring and two wells. A. veronii biovar sobria and A. jandaei were the predominant species in dams, and A. hydrophila and/or A. eucrenophila were predominant in wells. Almost all the sampled Aeromonas species produced protease, gelatinase, lipase, esterase and DNase, but A. caviae, A. caviae-like bacteria, and A. eucrenophila had low hemolytic activity. Most sampled A. hydrophila strains possessed both aerolysin gene (aer) and hemolysin gene (hlyA), but A. caviae and A. eucrenophila strains did not possess either gene. Conclusions Since these results indicated that several Aeromonas species having potential pathogenicity exist in environmental water in Okinawa, surveys are recommended as a public health measure.

Inactivation of the T6SS inner membrane protein DotU results in severe attenuation and decreased pathogenicity of Aeromonas veronii TH0426

“…Bacterial pathogenesis can be initially revealed from the study of genes encoding these virulence factors, which can also be explored by studying the release mechanism of effector proteins. Studies have shown that A. veronii carries a large number of virulence factors [22], but since its discovery, the lack of recognition has resulted in the study of only known virulence factors as well as the isolation and identification of pathogenic strains [23]. The unknown virulence factors specifically involved in metabolic pathways, including those regulating gene networks, and controlling the pathogenicity of strains are rarely studied, which is increasingly becoming one of the obstacles to revealing the specific pathogenesis of A. veronii.…”

Antibiotic and heavy metal resistance genes inAeromonasspp. isolated from marketed Manila Clam (Ruditapes philippinarum) in Korea

“…The mesophilic aeromonads are emerging as important pathogens in humans, among those mainly Aeromonas hydrophila , Aeromonas caviae and Aeromonas veronii bv. sobria have been predominantly found in clinical isolates (Miyagi et al ).…”

Investigation of Aeromonas: A Medical and Biotechnological Perspective

“…Aeromonas hydrophila is the predominant species in freshwater and municipal drinking water supplies and in Nigeria lakes, the isolated species were A. hydrophila and A. sobria [12]. Several Aeromonas species having potential pathogenicity were also investigated in environmental water of Okinawa and A. veronii biovar sobria and A. jandaei were reported as the predominant species in dams, and A. hydrophila and/or A. eucrenophila were predominant in wells [13]. However, our limited number of isolates did not allow us to characterize the predominant species A. hydrophila and extended studies are certainly required.…”