Pathology and virulence of Edwardsiella tarda, Edwardsiella piscicida, and Edwardsiella anguillarum in channel (Ictalurus punctatus), blue (Ictalurus furcatus), and channel × blue hybrid catfish

Abstract

In the mid‐2010s, Edwardsiella tarda was reaffiliated into three discrete taxa (E. anguillarum, E. piscicida, and E. tarda), obscuring previous descriptions of E. tarda‐induced pathology in fish. To clarify ambiguity regarding the pathology of E. tarda, E. piscicida, and E. anguillarum infections in US farm‐raised catfish, channel catfish (Ictalurus punctatus), blue catfish (I. furcatus), and channel × blue catfish hybrids were challenged with comparable doses of each bacterium. The most severe pathology and mortality occurred in fish challenged with E. piscicida, supporting previous reports of increased pathogenicity in commercially important ictalurids, while E. anguillarum and E. tarda warrant only minimal concern. Acute pathologic lesions among bacterial species were predominantly necrotizing and characteristic of gram‐negative sepsis but became progressively granulomatous over time. After 100 days, survivors were exposed to the approximate median lethal doses of E. piscicida and E. ictaluri, revealing some cross‐protective effects among E. piscicida, E. anguillarum, and E. ictaluri. In contrast, no fish that survived E. tarda challenge demonstrated any protection against E. piscicida or E. ictaluri. This work supports reports of increased susceptibility of channel, blue, and hybrid catfish to E. piscicida, while highlighting potential cross‐protective affects among fish associated Edwardsiella spp.

Case Report: Ambergris coprolite and septicemia in a male sperm whale stranded in La Palma (Canary Islands)

“…These results indicate the stranded sperm whale was undergoing a systemic bacterial infection of gastrointestinal origin, derived from a “toxic megacolon.” This “toxic megacolon” originated from a chronic active progressive obstructed colon caused by the coprolite. The septicemic bacteria involved, as identified by MALDI-TOF MS analysis were H. limosa, E. tarda and C. perfringens ; all of which are common bacteria of the gastrointestinal tract that have been associated to cause enteric septicemia ( 17 ) - in some cases specifically in marine mammals ( 18–20 ); as well as multiorgan hemorrhages and necrosis ( 21 , 22 ).…”

Investigation of mass mortality caused by multi-drug resistant Edwardsiella tarda in Oscar fish, Astronotus ocellatus from an ornamental fish farm, Kerala

“…The clinical signs such as petechial hemorrhage, necrosis of tissues in liver, spleen and kidney are typical of E. tarda infections which substantiated the present nding (Leung et al 2019). Armwood et al (2022) recently detected signi cant pathologic lesions, necrosis and sepsis in blue and channel cat sh induced by different species of virulent Edwardsiella like E. tarda through experimental challenge study. Generalized septicemia like severe hemorrhagic necrotizing hepatitis and splenitis typical of edwardsiellosis was observed in spotted sea bass infected with E. piscicida by Hu et al (2022).…”

Aspartate metabolic flux promotes nitric oxide to eliminate both antibiotic-sensitive and -resistant Edwardsiella tarda in zebrafish

“…Thus, orthogonal partial least square discriminant analysis (OPLS-DA) was employed to recognize the sample patterns of differential metabolomes. Here, t [1] was separated control and LTB4-R TET animals from the LTB4-S group, while t [2] differentiated control animals from the LTB4-R TET group and deviation of LTB4-S (Figure 5A). An S-plot was used to identify discriminating variables with cutoff values of ≤0.05 and ≥0.5 for the absolute value of covariance p and correlation p (corr), respectively, as biomarkers.…”

“…Edwardsiella tarda is a Gram-negative bacterium that causes infection in aquatic animals and humans, posing a threat to aquaculture industry and public health ( 1 , 2 ). Antibiotics are effective against bacteria, but the extensive use of these drugs leads to the development of antibiotic resistance due to the consequent selective pressure.…”