Detection of Hemolysins in Aeromonas spp. Isolates From Food Sources: PCR Analysis and Biological Activity

Aeromonas species are water-borne bacteria that are often found as environmental and food contaminants. They have been involved in human diarrhea disease and extraintestinal infections and are considered as emerging pathogens. These infections are probably acquired by food and water consumption, as there is a high prevalence of Aeromonas in the environment and food. From the species isolated, A. hydrophila, A. veronii biovar sobria , and A. caviae are the species most commonly implicated in human intestinal infections. The mechanism of pathogenesis is complex and not well understood. Aeromonas virulence is considered to be multifactorial. Toxins with hemolytic, cytotoxic, and enterotoxic activities have been described in many Aeromonas spp. The hemolytic activity of aeromonads is related to both hemolysin (aer A and hly A) and cytolytic enterotoxin (aer) genes. Several virulence factors have been identified in strains isolated from a number of sources. It is possible that more than one of the genes involved in hemolytic/enterotoxic activity occur in the same strain. One rational approach to determine whether Aeromonas strains have the potential to be virulent is to detect the presence of hemolysin and enterotoxin genes by polymerase chain reaction (PCR) assays. PCR results can be compared with biological assays to assess the expression of the hemolytic and cytotoxic effects.