The genus Aeromonas consists of gram-negative rods widely distributed in freshwater, estuarine, and marine environments [1,2]. Aeromonas species grow at a range of temperatures, although they are isolated with increasing frequency during warmer months (May through October in the Northern hemisphere). Aeromonas species cause a wide spectrum of disease syndromes among warm- and cold-blooded animals, including fish, reptiles, amphibians, mammals, and humans [3,4].
The genus Aeromonas was re-categorized from the family Vibrionaceae to the family Aeromonadaceae in the mid-1980s, when phylogenetic evidence from molecular studies became available to support this distinction [2,5,6].
The genus Aeromonas has been divided into two major groups :
- Motile, mesophilic species, including eight that can cause disease in humans (table 1).
- Non-motile, psychrophilic species that generally cause disease only in fish.
Aeromonas species are oxidase positive and ferment glucose. The organisms grow at a range of temperatures from 0 to 42ºC.