[The importance of aeromonads as a human pathogen]

The genus Aeromonas belongs to the family Aeromonadaceae of the order Aeromonadales and consists of 14 phenospecies and 17 genomospecies. They are gram-negative, oxidase-positive, facultatively anaerobic and glucose-fermenting rods. Members of the mesophilic genus Aeromonas spp. are ubiquitous in the aquatic environment and can be isolated from fresh, brackish and marine water. In nutrient-enriched waters they can attain large populations, particularly in the warm seasons at higher temperatures. Sewage effluents are also a major allochthonous source of the mesophilic aeromonads in the aquatic environment. Organisms of the mesophilic aeromonads also occur in fresh and processed foods, often in very high numbers. They have been isolated from a wide range of both animal and plant food, including raw red meat, fish, seafood or vegetables. This reflects undoubtedly the contact of that food with contaminated water. Species of Aeromonas (A. hydrophila, A. caviae, A. veronii) have been shown to be associated with food borne gastroenteritis, with wound infections acquired via water or with sepsis, peritonitis or meningitis. Unlike gastroenteritis, these infections can have fatal or serious debilitating outcomes. Aeromonas sepsis generally arises secondary to gastroenteritis or wound infection and is associated with high mortality rates. Underlying diseases, particularly liver cirrhosis, or immunsuppressive states also play a major role in the acquisition and outcome of these infections.