ARS | Publication request: Detection and Distribution of Flavobacterium Columnare in Experimentally Infected Channel Catfish (Ictalurus Punctatus) Using Culture and Polymerase Chain Reaction

Submitted to: Journal Of Applied Aquaculture
Publication Acceptance Date: June 9, 2003
Publication Date: September 1, 2004
Citation: Shoemaker, C.A., Bader, J.A., Nusbaum, K.E., Klesius, P.H. 2004. Detection And Distribution Of Flavobacterium Columnare In Experimentally Infected Channel Catfish (Ictalurus Punctatus) Using Culture And Polymerase Chain Reaction. Journal Of Applied Aquaculture.

Interpretive Summary: Flavobacterium columnare is an Gram negative bacterium that causes disease in many fish. This bacteria causes columnaris disease and is the second most important disease seen in the cultured catfish industry in the southeast. Researchers have shown the bacteria to be somewhat difficult to culture by standard methods (i.e., on media in the lab). We wanted to determine if a probe based on DNA using a polymerase chain reaction could be used to detect the bacteria in samples from fish infected in the laboratory. Flavobacterium columnare was detected by both culture and PCR in samples taken from mucus (fish slime), gill and muscle/skin. PCR was better at detecting the bacteria in the skin/muslce than was culture. The results suggest that PCR may be useful for rapid detection (about 8 h) of F. columnare as long as other methods (i.e., culture or microscopy) are used to confirm the results.

Technical Abstract: We examined the use of culture and polymerase chain reaction (PCR) to detect Flabobacterium columnare in experimentally infected fish. Five treatments were utilized which included immersion exposure to 106, 107, 108 colony forming units (CFU)/mL for 30 minutes, intramuscular injection of 108 CFU/fish and a negative control (i.e., immersion in Cytophaga broth). Flavobacterium columnare was isolated and detected in mucus 30 minutes following exposure by microbiological culture and PCR in all treatments except the negative controls. Gills were positive by culture and by PCR in all treatments at 30 minutes post treatment except the 106 CFU/mL immersion treatment which did not yield positive culture and PCR results until 1 h. Culture positive samples were observed in the internal organs (anterior and posterior kidney) and blood of the 107-8 CFU/mL treatments although at low numbers (< 10 CFU). Results of PCR paralleled that of culture for the mucus and gill samples when analyzing all treatments together over time suggesting either method is useful in determination of the presence of F. columnare. Polymerase chain reaction was significantly (P<0.001) better at detection of F. columnare from skin/muscle than was the use of microbiological culture. These results suggest that PCR may be useful for rapid detection of F. columnare in the mucus.