DETECTION OF RENIBACTERIUM-SALMONINARUM IN SALMONID KIDNEY SAMPLES - A COMPARISON OF RESULTS USING DOUBLE-SANDWICH ELISA AND ISOLATION ON SELECTIVE MEDIUM

A total of 1239 kidney samples from four species of salmonid fish, Atl antic salmon, Salmo salar L., brown trout, Salmo trutta L., Arctic cha rr, Salvelinus alpinus (L.), and rainbow trout, Oncorhynchus mykiss (W albaum), were screened for Renibacterium salmoninarum using double-san dwich ELISA and bacterial isolation. For bacterial isolation. samples were homogenized, washed, plated onto S-KDM and incubated for 12 weeks . Samples for ELISA were kept frozen until tested. After thawing, 25% homogenates in PBS were heated at 100-degrees-C for 15 min in the pres ence (2.5% v/v) of HemoDe solvent (terpene and butylated hydroxyanisol e) and then centrifuged. The supernatant was tested with polyclonal an tibodies against whole bacterium in a double-sandwich ELISA. In seven out of 12 groups tested, all samples were negative in both tests. Posi tive ELISA results occurred in five groups. Renibacterium salmoninarum was isolated on SKDM from samples in four out of these five groups. T he ELISA test gave significantly higher numbers of positive samples in three out of the four groups showing positive results in both tests.