Location: Aquatic Animal Health Research
Title: Rapid detection of Flavobacterium columnare, the bacterium causing Columnaris Disease in fish Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2007
Publication Date: May 3, 2007
Citation: Panangala, V.S., Shoemaker, C.A., Klesius, P.H. 2007. Rapid detection of Flavobacterium columnare, the bacterium causing Columnaris Disease in fish. Flavbacterium 2007. May 2007. page 44. Technical Abstract: Flavobacterium columnare is a ubiquitous bacterium that causes columnaris disease in a wide variety of fish resulting in devastating losses particularly in the commercial aquaculture industry worldwide. Timely diagnosis of disease is imperative for prevention of spread and to reduce the economic loss to fish farmers. Two diagnostic tests for rapid detection of F. columnare in infected fish were developed. An indirect immunofluorescence (IFA) test with dual spectral properties was compared with bacteriological culture (accepted standard) for simultaneous detection of Edwardsiella ictaluri (the cause of enteric septicemia of channel catfish) and F. columnare. A total of 303 samples (derived from kidney, brain and nares) from 101 experimentally infected fish examined concurrently by IFA and culture, revealed that the IFA test compared favorably in sensitivity (EI = 80.7%; FC = 87.2%) and specificity (EI = 83.9%; FC = 88.9%) with the standard culture. In a separate experiment, the sensitivity and specificity of a TaqMan real-time polymerase chain reaction (RT-PCR) targeting a 113 bp nucleotide region of the chondroitin AC lyase gene of F. columnare was evaluated. Specificity of the assay evaluated with 20 isolates of F. columnare and 15 other taxonomically or ecologically related bacteria revealed that the primers and probe were 100% specific for detection of F. columnare. In tissues (blood, gills and kidney) of F. columnare experimentally infected fish, the bacterial numbers assessed by RT-PCR ranged from 3.4 x 10 to zero power to 9.5 x 10 to the fifth power CFU/ml. The diagnostic assays developed are sensitive and specific for detection of F. columnare in infected fish.