Abstract
The action of acriflavine solutions on Bacterium salmonicida has been the object of several studies 1 , 2 , 3 because of its efficacy in the prophylactic disinfection of the exterior of trout eggs to prevent the spread of Bacterium salmonicida infection (trout furunculosis).
None of these reports has recorded the action of organisms tested in the various phases of the growth curve. Furthermore, a search of the literature has revealed no data on the relative sensitivity to lethal agents of the growth phases of an organism grown near its optimum temperature as compared to organisms grown near the minimum.
Using a modification 3 of the method of Ruehle and Brewer 4 for testing disinfectants, Bact. salmonicida cultures incubated for various periods of time and at 2 different temperatures (15°C and 10°) were exposed to the action of 500 parts per million (p.p.m.) of alkaline acriflavine.∗ The tests of the 15° cultures were run at pH 7.7, those grown at 10° at pH 8.0. The disinfection studies were run at 10°.
Table I summarizes the tests and Fig. 1 presents the death curve of the cultures.
The cultures grown at 15° showed little variation. There was a slight but definite increase in resistance to the dye as the culture aged. A peculiarity (autoagglutination) of the test organism prevented the procurement of bacterial counts. Therefore, it was not possible to compensate for the variations in load of organisms at each time interval. Had this been possible the death time of the youngest and oldest cultures would probably have been prolonged. The curve of death would have been U-shaped.
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