Bacteriological and Histopathological Studies on Vibrio Species Isolated from Naturally Infected Freshwater Fish in Delta Region, Egypt

The study was aimed to elucidate the most predominant vibrio serovars isolated from naturally infected freshwater fish in the delta region, Egypt. The contamination of water with Cupper and Iron was evaluated. Fishes (n=200) were examined clinically and upon post-mortem. Bacteriological identification was confirmed based on the cultural characteristics and biochemical activities of isolates. A total of 5 isolates of Vibrio harveyi and Vibrio alginolyticus were further examined for the presence of hemolysins (vhh) and collagenase encoding genes using PCR, respectively. The data revealed that Vibrio species were recovered from 39% (78/200) of the examined fishes, and the highest prevalence rate was observed for Angillaangilla (55%) while the lowest was observed for Chrysichthys auratus and Oreochromsniloticus (35%). The V. harveyi was the predominant isolate (29.48%, 23/78), followed by V. anguillarum (28.20%, 22/78), V.vulnificus (16.67%, 13/78), V. alginolyticus (15.38%, 12/78), and V. fluvialis (10.25%, 8/78). Among five examined Vibrio harveyi and Vibrio alginolyticusisolate, a total of 4 (80%) were found to harbor hemolysins (vhh) and collagenase, respectively. Areas where vibrio was recovered in a high percentage, water contamination with Cupper and Iron was higher than the permissible limit. Taken together, the obtained information established the emergence of V. harveyi as a widespread Vibrio serovar warrants further studies to elucidate its public health impact.