Species of Aeromonas are Gram-negative, non-spore-forming, rod-shaped, facultatively anaerobic bacteria that occur ubiquitously and autochthonously in aquatic environments. Although historically the Aeromonas genus has been placed in the family Vibrionaceae, there have been proposals to place it in its own family, the Aeromonadaceae. The aeromonads share many biochemical characteristics with members of the Enterobacteriaceae, from which they are primarily differentiated by being oxidase-positive. The genus includes at least 13 genospecies, among which are the mesophilic A. hydrophila, A. caviae, A. sobria, A. veronii, and A. schubertii, and the non-motile, psychrophilic A. salmonicida
Aeromonas is a genus of bacteria that is ubiquitous in the environment. It is present in all types of water worldwide as well as food and soil. The genus Aeromonas consists of gram-negative rods. These organisms are oxidase-positive and facultatively anaerobic. The role of Aeromonas spp. in causing disease in humans is perhaps the most controversial one, especially when it comes to the digestive tract illnesses such as diarrhoea. Current evidence for Aeromonas being a human pathogen focuses not just on gastrointestinal illnesses but also other infections that Aeromonas isolates have been associated with including injury or wound infections, nosocomial infections, septicaemia, respiratory tract infections and peritonitis.