First detection of Edwardsiella ictaluri (Proteobacteria: Enterobacteriaceae) in wild Australian catfish

Abstract

The bacterium Edwardsiella ictaluri is considered to be one of the most significant pathogens of farmed catfish in the United States of America and has also caused mortalities in farmed and wild fishes in many other parts of the world. E. ictaluri is not believed to be present in wild fish populations in Australia, although it has previously been detected in imported ornamental fishes held in quarantine facilities. In an attempt to confirm freedom from the bacterium in Australian native fishes, we undertook a risk-based survey of wild catfishes from 15 sites across northern Australia. E. ictaluri was detected by selective culturing, followed by DNA testing, in Wet Tropics tandan (Tandanus tropicanus) from the Tully River, at a prevalence of 0.40 (95% CI 0.21-0.61). The bacterium was not found in fishes sampled from any of the other 14 sites. This is the first report of E. ictaluri in wild fishes in Australia.

Genotypic and phenotypic characterization of Edwardsiella isolates from different fish species and geographical areas in Asia: Implications for vaccine development

“…It causes septicaemia, extensive skin lesions and pathology in various internal organs linked to high mortalities and sporadic epidemics in different fish species (Plumb, 1999;Shetty et al, 2014;Ullah & Arai, 1983). In 1980, the second member of the genus Edwardsiella was characterized by Grimont, Grimont, Richard, and Sakazaki (1980) as E. hoshinae, which has been isolated from birds, reptiles, human faeces and water samples (Castro, Toranzo, Nunez, & Magariños, 2008;Grimont et al, 1980), while the third member was classified as E. ictaluri by Hawke, McWhorter, Steigerwalt, and Brenner (1981) in 1981 mainly causing disease in catfish (Kelly et al, 2018;Kim & Lovell, 1995;Reichley, Waldbieser, Soto, Lawrence, & Griffin, 2017). Recent advances in genotyping have led to the classification of fish isolates previously classified as E. tarda to be E. piscicida by Abayneh, Colquhoun, and Sørum (2013) in 2013, while isolates from eel (Anguilla anguilla) were classified as E. anguillarum by Shao et al (Ucko, Colorni, Dubytska, & Thune, 2016) in 2015.…”

Monitoring the Starvation–Survival Response of Edwardsiella piscicida and E. tarda in Freshwater Microcosms, at Various Temperatures

“…Some authors have highlighted the role of the intestine as a gateway for the Edwardsiella since they can cross intestinal mucosa, such as other enteric pathogens ingested through water or food [ 2 , 34 ]. Although the presence of Edwardsiella in the intestines of healthy wild fish has been reported [ 6 , 10 , 11 ], the role of water as a reservoir for these bacteria is still unknown. Specifically, it is unknown whether the Edwardsiella are capable of surviving in such an oligotrophic environment even after their exposure to different temperature conditions.…”

“…The search for Edwardsiella reservoirs in wild aquatic vertebrates and natural surface waters has primarily been a public health issue [ 6 , 7 ] because E. tarda cause water- and foodborne infection in humans [ 2 ]. To date, the Edwardsiella have been effectively isolated from diseased aquatic vertebrates [ 8 , 9 , 10 ] and, to a lesser extent, from “healthy carriers” [ 6 , 10 , 11 ]. In addition, E. tarda have been isolated from natural surface freshwater on a few occasions [ 8 , 10 ].…”

Environmental factors affecting Edwardsiella ictaluri‐induced mortality of riverine ayu, Plecoglossus altivelis (Temminck & Schlegel)

“…Edwardsiella ictaluri is also often associated with mortality in farmed non‐catfish species such as rainbow trout Oncorhynchus mykiss (Keskin et al., 2004), Nile tilapia Oreochromis niloticus (Soto et al., 2012) and some ornamental fishes (Evans et al., 2011; Hawke et al., 2013). However, there have been no reports about mortality of wild fishes caused by E. ictaluri , although the pathogen has been detected in several wild catfish species (Chen et al., 1994; Kelly et al., 2018; Klesius et al., 2003).…”