飽和食塩水浮遊法の改良による室内塵中のダニ検出について

Abstract

An improved floatation method with saturated sodium chloride solution for isolation of house dust mites was described. Dust samples were collected from the houses of asthma patients by a vaccuum cleaner. A portion of the fine dust that passed through a 36-mesh sieve and retained on a 200-mesh sieve was suspended in saturated sodium chloride solution in a 100-ml flask (0.1g fine dust/flask) for 30min. Although mites have been isolated only from the upper fraction of the floatation solution in the conventional method, the recovery rates were low (31.7% in average) and varied by samples. Hence, in our method the mites were isolated from the whole floatation solution, except the residue fraction, as well as washed from the flask wall (whole isolation method). The recovery rates rose to 92.3% in average. Isolating mites from the residue fraction was not practical as it is a time-consuming procedure. The isolation efficiency of the method was compared with that of floatation and centrifugation methods by using two mite-culture media prepared in the laboratory. One medium was a mixture of powdered rat food pellets and yeast extract (1 : 1,Medium A); the other, a mixture of Medium A and fine dust (1 : 10,Medium B). D. farinae had been reared on these media for 2 months. The recovery rate from Medium A was 89.4% in average by the whole isolation method. The rate did not increase by soaking the medium in 80% ethanol solution for 4hr. The accumulative recovery rates of 3-time centrifugations were almost same as those of the whole isolation method. The whole isolation method was considered to be more efficient, simpler and cheeper than any other method so far described for isolation of house dust mites.