Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Veterinary Hygiene and Management

The current study aimed to investigate the most common pathogenic bacteria that naturally infected wild marine fishes collected at different localities along the coastaline zone of Hurghada City, Egypt. A total of 550 samples of marbled spinefoot Siganus rivulatus and the Haffara Seabream Rhabdosargus haffara were subjected to clinical and bacteriological examinations.The examined fishes showed the characteristic clinical signs and postmortem lesions of vibriosis, photobacteriosis streptococcosis and tenacibaculosis. Based on the morpho-chemical characterization, bacterial isolates retrieved from the naturally infected fishes were identified as Vibrio spp., Photobacterium spp,Through sequencing 16S rRNA genes, the identities of bacterial isolates were confirmed as V. alginolyticus, V. vulnificus, P. damselae subsp damselae, P. damselae subsp piscicida, Enterococcus fecalis, Streptococcus iniae, Enterobacter cloacae and Tenacibaculum maritimum.Vibrio alginolyticus was the most frequent isolated bacterial pathogen of the total isolates recovered from S. rivulatus and R. haffara. Thus, the current study confirms that Vibrio spp., Photobacterium spp.,Streptococcus spp., and Tenacibaculum spp. remain the most prevalent bacterial pathogens infecting Egyptian Red Sea fishes. From food safety perspective, these types of infections could pose potential public health hazards

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