Detection and Distribution of Flavobacterium columnare inExperimentally Linked Channel Catfish, Ictalurus punctatus, UsingCulture and Polymerase Chain Reaction

摘要

We examined the use of culture and polymerase chain reaction (PCR) to detect Flabobacterium columnare in experimentally-infected channel catfish, Ictalurus punctatus. Five treatments were utilized which included immersion exposure to 10 super(6), 10 super(7), 10 super(8) colony forming units (CFU)/mL for 30 minutes, intramuscular injection of 10 super(8) 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 10 super(6) CFU/mL immersion treatment which did not yield positive culture and PCR results until 1 hour. Culture positive samples were observed in the internal organs (anterior and posterior kidney) and blood of the 10 super(7-8) CFU/ mL treatments although at low numbers ( less than or equal to 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.