Practice 26 - Isolation and counting of Aeromonas hydrophila

Abstract

Aeromonas species have straight rods and are motile by a polar flagellum. Psychrotrophic Aeromonas species grow in foods at chilled temperatures. Their principal reservoir is the aquatic environment, for example, freshwater lakes, streams, and wastewater system; but most commonly they are associated more with saltwater than freshwater. Aeromonas infections in people is predominantly during warm weather. People are mainly contaminated from water, soil, seafood, or other infected people. Aeromonas hydrophila, Aeromonas sobria, and Aeromonas caviae can cause gastroenteritis. Virulent strains of A. hydrophila produce heat-labile, β-hemolytic, and cytotoxic enterotoxin. A. hydrophila infection is associated with water, poultry, seafoods, raw milk, ice cream, and salad vegetables. A. hydrophila grows on a wide variety of enteric media. Bile salts and ampicillin are selective agents for the selective isolation of A. hydrophila. Modified XLD agar can be used as a selective/differential medium in the isolation and counting of Aeromonas.