Submitted to: Journal of Aquatic Animal Health
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/13/2004
Publication Date: 8/1/2004
Citation: Klesius, P.H., Lovy, J., Evans, J.J., Washuta, E., Arias, C. 2004. Isolation of Edwardsiella Ictaluri from tadpole madtom, Noturus gyrinus in a southwestern New Jersey River. Journal of Aquatic Animal Health. 15(14):295-301. Interpretive Summary: In this study we reported for the first time the isolation of the fish pathogen Edwardsiella ictaluri from tadpole madtom collected from the Cohansey River in Cumberland County, New Jersey. Fish with disease symptoms were sampled and bacterial colonies were isolated from different lesions. The bacterial isolates were characterized using four different bacterial identification methods including biochemical, physiological, and genetic techniques. All the methods agreed to identify the isolates as Edwardsiella ictaluri. Further characterization of the isolates revealed they were genetically similar but distinct from other E. ictaluri isolates; therefore they constitute a new strain among the species. We proved this new strain was able to cause enteric septicemia (ESC) in catfish achieving a mortality rate of 60% after intraperitoneal injection with the bacterium
Technical Abstract: In 2002, New Jersey Division of Fish and Wildlife biologists conducted an aquatic assessment in a section of the Cohansey River in Cumberland County, New Jersey. Three of seven tadpole madtom, Noturus gyrinus, collected were observed to have an ulcerative lesion on the head between the eyes. Gram negative, oxidase-negative rods were isolated from the head kidneys of two of the madtoms and the cranial ulcer of the third madtom. Four different identification methods, API-20E, whole cell fatty acid methyl esters (FAME), BIOLOG, and enterobacterial repetitive intergenic consensus (ERIC) sequences ascribed the isolates to the species E. ictaluri. A phenotypic comparison, using FAME and BIOLOG data, revealed that E. ictaluri isolates from wild madtom shared a high degree of similarity to E. ictaluri isolates from cultured channel catfish having enteric septicemia of catfish (ESC) from Alabama and Mississippi. However, when fingerprinted by amplified fragment length polymorphisms (AFLP) the three madtom isolates proved to be genetically different from the other E. ictaluri isolates. Koch¿s postulates were fulfilled using the tadpole madtom E. ictaluri isolate in juvenille channel catfish. Sixty percent mortality was achieved in catfish intraperitoneally injected with 1 ¿ 104 CFU/fish. The results indicate that the ictalurid, tadpole madtom, is susceptible to ESC by natural infection.