[Value of the color test in assessing the viability of cysts of Acanthamoeba sp].

The eosin colour test estimating the viability of cysts was compared with the method of in vitro excystation on agar substrate (NNE). Single cysts were studied, isolated from populations stored under sterile conditions in water at 4 degrees C for a period ranging from a few days to 16 years. It has been found that the inoculations of single cysts (805 cysts) on the NNE substrate allow a precise determination of the percentage of living cysts. All the cysts stained with eosin, incubated on such a substrate proved to be dead, while the non-staining cysts ex-cistated with varying percentage. Thus, among the non-staining cysts of Acanthamoeba after 2-4 years of storage at 4 degrees C 89.2% excystated while the remaining ones were dead. After 16 years of storage only 29.8% nostaining cysts excystated. Very similar values (89.6 and 28.5% respectively) were obtained when determining the percentage of living cysts with the colour test. The eosin test has proved to be a good method of the estimation of the viability of cysts of Acanthamoeba.