Studies on Vibrio Alginolyticus Infection Among Some Red Sea Fishes at Hurghada

Abstract

Bacteria are one of the most prevalent causes of morbidity and mortality among wild fishes. Vibrio alginolyticus (V. alginolyticus) is a serious fish pathogen. This study was performed to investigate prevalence of V. alginolyticus infection among six species of Red Sea fishes at Hurghada city, Egypt through clinical and bacteriological examinations and to determine pathogenicity of the isolates and their antimicrobial susceptibilities. Therefore, a total number of 180 fish from these six fish species (30 fish of each species) were randomly collected from the Red Sea at Hurghada city during the period from October 2019 to March 2020 and subject to clinical and bacteriological examinations. Based on the morphological and biochemical characteristics of the isolates, 64 homogenous V. alginolyticus isolates were isolated and phenotypically identified from the examined fishes with prevalence of (26.7%), (20%), (63.3%), (36.7%), (23.3%) and (43.3%) among Lutjanus ehrenbergii (L. ehrenbergii), Lethrinus borbonicus (L. borbonicus), Siganus rivulatus (S. rivulatus), Rhabdosargus haffara (R. haffara), Scarus ghobban (S. ghobban) and Cheilinus lunulatus (C. lunulatus) fishes respectively. Afterthat, representative isolates were cofirmed as V. alginolyticus by 16S rRNA gene sequence and deposited in GenBank as V. alginolyticus MR-C17 (GenBank accession no. MW790239). The V. alginolyticus infected fishes exhibited skin dark coloration, scales loss, hemorrhages on several parts of the body surface, mouth, base of fins, abdomen, opercula and around the anal opening, eroded fins, ascites, swollen intestine and congestion or paleness of the internal organs espeially liver. Antimicrobial susceptibility testing of V. alginolyticus isolates revealed that they were sensitive to chloramphenicol, tetracycline, ciprofloxacin and ofloxacin and resistant to ampicillin, cephalothin, amikacin, streptomycin, cefotaxime, erythromycin, oxolonic acid, amoxicillin/clavulanic acid, tobramycin and clindamycin. Pathogenicity test revealed that V. alginolyticus MR-C17 was pathogenic to R. haffara with 80 % mortalities in the experimentally infected fish which showed similar clinical signs and post-mortem (PM) lesions to thoes observed in the naturally infected fishes.

Prevalence, genetic diversity, and antimicrobial susceptibility of Vibrio spp. infected gilthead sea breams from coastal farms at Damietta, Egypt

“…The antibiotic sensitivity and MDR pattern conform with those reported by El-Sayed et al [ 71 ]. Antibiotic resistance indicates the presence of antibiotic residues in aquaculture ecosystems.…”