The Quantitative Clearance of Bacteria from the Bloodstream of Rainbow Trout (Salmo gairdneri)

Abstract

The blood clearance of 51Cr-labelled heat-killed Salmonella pullorum was biphasic and exponential for each phase. This pattern was the same for all three concentrations of bacteria used. The initial more rapid phase lasted for approximately 15 minutes when roughly 90% of the bacteria had been cleared. The second slower phase started 25 to 30 minutes post-inoculation and lasted for approximately 25 to 30 minutes. The tissue distribution of bacteria showed that in both absolute and relative terms, the kidney was the most important organ, accounting for more than 70% uptake of the bacteria. These kinetics demonstrate that rainbow trout at 8°C are able to clear their bloodstream of Salmonella very efficiently, in a fashion very similar to mammals. It is not known, however, which of the various possible clearance mechanisms dominates each phase.