ABSTRACT
Aeromonads have been recognized as potential food borne pathogens for more than 20 years. Aeromonas species is ubiquitous in aquatic environments / components including fresh water, fish and shellfish. Clinical infections of Aeromonads usually result in heavy losses in both marine and freshwater aquaculture. The main goal of our research was to investigate the occurrence of potentially pathogenic Aeromonas species in the River Nile, Egypt during the year 2009/2010. Six hundred and twenty six random isolates of typical colonies of Aeromonads were isolated from water/ fish and then further confirmed by PCR. Moreover, we have demonstrated the DNA damage in fish organs because of exposure to polluted water. Five hundred and sixty one isolates were confirmed to be Aeromonas species. Only two hundred and seventy six isolates were confirmed to be A. hydrophila when strains were analyzed for the presence of the aerolysin (aerA) and hemolysin (hylaA) genes by PCR amplification using specific primers targeting a 416 bp fragment of the aerA domain and 597 bp fragment of the hylaA domain. In conclusion, this PCR-based method is rapid, sensitive, and specific for the detection of Aeromonas species. Additionally, such methodologyovercomes the lengthy and time-consuming biochemical and other DNA-based methods. Finally, our data suggested that fish has been considered as a reservoir of pathogenic aeromonads.
Keywords: River nile, Fish, Aeromonas hydrophila, PCR technique.