[Pathogenicity of Acanthamoeba isolated from water]

Abstract

Two Acanthamoeba strains were isolated from rivers in Berlin by intranasal inoculation into mice. No clinical or pathological symptoms could be observed in the animals. The intention of this study was to initiate and to increase the pathogenicity of these amoebae. The two strains were passaged in mice as well as in liquid medium followed by inoculation into mice. The pathogenicity was measured by the rate of lethality. The first cases of death were found after the 10th passage in those mice which had been infected with the amoebae only passaged in animals. Acanthamoebae could be isolated from brains and lungs, but pathological changes were found only in lungs. After the 11th and 12th animal passage, respectively, the amoebae were only cultivated in vitro for 15 weeks followed by another series of animal passages. Here, first cases of death were recorded after the 5th and 3rd inoculation into mice, respectively. No animals died having been infected with amoebae only maintained in vitro. A third experiment with animal passaged strains showed that mice died even up to the 6th week p.i. and that amoebae could be re-isolated until the 7th week i.p. The results are discussed in view of a possible selection of pathogenic Acanthamoeba strains by fast passages from man to man.