Aeromonads in Environmental Waters

Abstract

The normal habitat of Aeromonas species is the aquatic environment, and they represent a high percentage of the heterotrophic microorganisms in a variety of aquatic systems; for this reason, the potential public health significance cannot be ignored (1). Their presence has been reported in sewage and sewage effluents, surface waters (fresh, estuarine, and marine), fish ponds, soils, natural mineral springs, stagnant water, chlorinated and unchlorinated drinking water, and especially fresh waters (see Notes 1 and 2). The motile species are often ubiquitous members of the aquatic ecosystem (2). But all can be components of the microbial flora of aquatic animals, and may be pathogens of poikilotherms, homoiotherms, and even man (3). They act as primary pathogens and make a significant contribution to the disease process in fish that they invade (4). They may cause clinical dropsy, ulceration, and widespread tissue necrosis (5). Losses may be substantial, and control is dependent on eliminating the underlying factors predisposing to infection. A. salmonicida and A. hydrophila occupy two well-differentiated ecological niches. A. salmonicida is a natural parasite of fish and other poikilotherms, and is normally found free in the water. A. hydrophila belongs to the fish microflora and is ubiquitous in all types of aqueous environments (6).