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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Virulence of Aeromonas hydrophila to channel catfish Ictalurus punctatus fingerlings in the presence and absence of bacterial extracellular products

Authors
item Wei Pridgeon, Yuping
item Klesius, Phillip

Submitted to: Diseases of Aquatic Organisms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 14, 2011
Publication Date: July 12, 2011
Repository URL: http://handle.nal.usda.gov/10113/55877
Citation: Wei Pridgeon, Y., Klesius, P.H. 2011. Virulence of Aeromonas hydrophila to channel catfish Ictalurus punctatus fingerlings in the presence and absence of bacterial extracellular products. Diseases of Aquatic Organisms. 95:209-215.

Interpretive Summary: Virulence of three 2009 West Alabama isolates of Aeromonas hydrophila in the presence or absence of extracellular products (ECP) from overnight bacterial culture to channel catfish fingerlings was investigated by both bath immersion and intraperitoneal injection routes. The absence of extracellular products in bath immersion significantly increased the virulence of all isolates. Filter sterilized extracellular products failed to kill any catfish by bath immersion or injection. At 2h post bath immersion, all four isolates of bacterium Aeromonas hydrophila were found in all tissues studied (skin, intestine, liver, spleen, kidney, gill, and brain), with the highest bacteria count in the gill and kidney.

Technical Abstract: Virulence of three 2009 West Alabama isolates (AL09-71, AL09-72, and AL09-73) of Aeromonas hydrophila in the presence or absence of extracellular products (ECP) from overnight bacterial culture to channel catfish fingerlings (4.6 +/- 1.3g) was investigated by both bath immersion and intraperitoneal injection routes. At concentration of 1.65 ×100,000,000 CFU/ml, AL09-73 without its ECP killed 100% catfish fingerlings within 2h by bath immersion. However, at similar concentration, AL09-73 in the presence of its ECP only killed 23 +/- 6% catfish fingerlings. The absence of ECP in bath immersion also significantly (P<0.05) increased the virulence of AL09-71, AL09-72, and AL98-C1B, a 1998 Alabama strain of A. hydrophila, suggesting the virulence of the four isolates of A. hydrophila was mainly due to bacterial cells, not their overnight ECPs. Filter sterilized ECPs failed to kill any catfish by bath immersion or injection. The virulence order of the four A. hydrophila isolates by both bath immersion and intraperitoneal injection was: AL09-73>=AL09-71>=AL09-72>=AL98-C1B. At 2h post bath immersion, all four isolates of A. hydrophila were found in all tissues studied (skin, intestine, liver, spleen, kidney, gill, and brain), with the highest bacteria count in the gill and kidney.

Last Modified: 12/20/2014
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