A New Outbreak in Sea Bass Farming in Turkey: Aeromonas veronii

Abstract

Turkey produces most of the European sea bassin Europe and bacterial diseases are the main cause of economic loss during the production cycle. This research presents the first extended study of the Aeromonas veronii infection in sea bass on the Turkish coast of the Aegean Sea. An outbreak was observed in three different sea bass farms and diseased fish with clinical symptoms were sampled. Abdominal distention, hemorrhages on the body and anus, enlarged spleen and liver, and hemorrhages in the internal organs were detected from clinical and pathological examinations. Biochemical and molecular identification confirmed the pathogen to be A.veronii.The histopathological observations demonstrated that the pathogen caused bacterial colonies in the fibrous connective tissue, granuloma, and vacuolar degeneration.The primary causes of the disease were proved through an infection experiment. 80% and 90% mortality were calculated in 0.85 x 108 CFU ml-1 and 1.28 x 108 CFU ml-1 experimentally infected groups with clinical and pathological signs of the disease respectively. Recently, the pathological symptoms of the disease had been confused with pasteurellosis infection in cage farms but the presence of A.veronii has been confirmed in the current study. A detailed study is needed to investigate the overall status of the disease in the Aegean Sea in order to design an appropriate preventive strategy.

The role of Aeromonas genotyping in virulence for Dicentrarchus labrax

“…In the present study, the LD 50 of A. veronii in D. labrax fingerlings was (>1 × 10 8 to 6.2 × 10 7 ) CFU fish −1 ; this value was higher than the value recorded by (Smyrli et al, 2017(Smyrli et al, , 2019Wang et al, 2021) was 10 5 , 4.2-8.5 × 10 5 and 1.4-2.4 × 10 6 , respectively, while it was nearly similar to the LD 50 estimated by Tanrıkul and Dincturk (2021) which was 0.85-1.28 × 10 8 , variation in the LD 50 is attributed mainly to the difference in virulence and pathogenicity of challenging isolates. LD 50 of A. caviae in D. labrax ranged between 2.9 and 8.3 × 10 7 CFU.…”

“…Our results revealed the presence of haemorrhagic skin lesions, exophthalmia, cataracts, congested liver, spleen and posterior kidney. Accordingly (Smyrli et al., 2017, 2019; Tanrıkul & Dincturk, 2021; Wang et al., 2021) have described identical clinical signs and post‐mortem lesions in naturally and experimentally infected D. labrax . Similar findings were also mentioned by Azzam‐Sayuti et al.…”

“…The infection has been previously reported in many cultured freshwater fish species, including Carassius auratus , Cyprinus carpio , Ctenopharyngodon idella and Silurus asotus (Li et al., 2020), Oreochromis niloticus (Reda et al., 2022), carp (Ran et al., 2018), Leiocassis longirostris (Cai et al., 2012), Astronotus ocellatus , Carassius Carassius (Sreedharan et al., 2013) and Lateolabrax maculatus (Wang et al., 2021). Meanwhile, A. veronii infection is less abundant in cultured marine fishes as it was reported only from diseased European seabass (Smyrli et al., 2019; Tanrıkul & Dincturk, 2021). To the best of our knowledge, this is the first record of A. caviae isolation from diseased seabass, even from any diseased marine fish species.…”

The role of Aeromonas genotyping in virulence for Dicentrarchus labrax

“…Meanwhile, A. veronii infection is less abundant in cultured marine fishes as it was reported only from diseased European seabass (Smyrli et al, 2019;Tanrıkul and Dincturk, 2021). To the best of our knowledge, this is the first record of A. caviae isolation from diseased seabass or even from any diseased marine fish species, A. caviae has previously been isolated from diseased freshwater fishes as Rhamdia quelen (Baldissera et al, 2018), Oreochromis niloticus (Roy et al, 2018), Clarias gariepinus (Mulia et al, 2020), red hybrid tilapia (Azzam-Sayuti et al, 2021) and Pelteobagrus fulvidraco (Zhai et al, 2021).…”

Winter Kills in Farmed European Seabass (Dicentrarchus labrax): Co- infected with Shewanella putrefaciens and Aeromonas veronii

“…1 and 2). European seabass infected with S. putrefaciens and A. hydrophila revealed epidermal lesions progressively extended to musculature (muscle ulceration), hemorrhagic caudal fins, fin rot, red inflamed vents and abdominal distension (Korun et al, 2009;Smyrli et al, 2017;Tansel Tanrikul and Dinçtürk, 2021). Similar clinical signs have been previously reported in rabbitfish, Siganus rivulatus (Saeed et al, 1987) The phenotypic characterization of bacterial isolates demonstrated that five isolates had phenotypic characteristics corresponded to Shewanella putrefaciens and three isolates had phenotypic characteristics corresponded to Aeromonas species (Table 1).…”