Immunofluorescence screening of Renibacterium salmoninarum in the tissues and eggs of farmed chinook salmon spawners

Concentrations of erythromycin and azithromycin in mature Chinook salmon Oncorhynchus tshawytscha after intraperitoneal injection, and in their progeny

“…Nevertheless, azithromycin exhibited a clear pharmacokinetic advantage over erythromycin, demonstrated by the high, stable concentrations maintained in blood plasma, kidney, coelomic fluid and egg vitellin of maturing female salmon throughout the 32 d spawning period. These findings are of particular clinical relevance, because eggs may acquire infections during oogenesis (Lee & Gordon 1987) or from contaminated coelomic fluid following ovulation (Lee & Evelyn 1989).…”

“…In captive broodstock programs rearing endangered Pacific salmon, subadult fish are treated prophylactically using erythromycin as a feed additive, administered at daily dosages of 100 mg kg -1 for 21 to 28 d of continuous therapy (Wolf & Dunbar 1959, Peters & Moffitt 1996. Then, because eggs may acquire infections during oogenesis (Lee & Gordon 1987) and following ovulation when they are surrounded by contaminated coelomic fluid (Lee & Evelyn 1989), maturing adult salmon are given a single ABSTRACT: A single dose (40 mg kg -1 ) of erythromycin or azithromycin dihydrate was injected intraperitoneally into maturing female fall Chinook salmon 12 to 32 d before spawning to observe the distribution, retention and clearance of the drugs in plasma, kidney, coelomic fluid and egg vitellin, and their persistence in alevins derived from these fish. Salmon administered prophylactic dosages of erythromycin as subadults were also included to investigate potential interactive effects of oral and injected treatments on reproductive performance and antibiotic clearance.…”

Brood stock segregation of spring Chinook salmon Oncorhynchus tshawytscha by use of the enzyme-linked immunosorbent assay (ELISA) and the fluorescent antibody technique (FAT) affects the prevalence and levels of Renibacterium salmoninarum infection in progeny

“…Bruno & Munro (1986) showed that developing oogonia of rainbow trout could become infected when the fish were injected intraperitoneally with 2.7 X 107 R. salmoninarum cells each. Lee & Gordon (1987a) and Lee & Evelyn (1989) suggested that some infections detected in the progeny of females with few or no bacteria in the ovarian fluid may represent intra-ovum infections acquired from ovarian tissue before ovulation. We cannot rule out the possibility that some of the eggs in our study groups became infected before ovulation.…”

“…One could also substitute a more conventional FAT in which bactena are concentrated from ovarian fluid by centrifugation and the pellet is smeared on a microscope slide (smear FAT; Lee & Gordon 1987a, Armstrong et al 1989b), but research results suggest that this method may lack the necessary sensitivity. In a screening test of ovarian fluid from chinook salmon, Armstrong et al (1989b) found that 60 O/ O of the samples were falsely negative by the smear FAT in comparison with culture, and that the FAT results obtained by 2 independent laboratories for samples from the same fish were inconsistent.…”

Control of vertical transmission of Renibacterium salmoninarum by injection of antibiotics into maturing female coho salmon Oncorhynchus kisutch

“…Eggs have been shown to acquire infections following ovulation when surrounded by heavily contaminated coelomic fluid (Evelyn et al 198613) and there is also evidence that they can become infected during oogenesis (Lee & Gordon 1987, Lee & Evelyn 1989.…”