Epidemiology studies of clinical isolates of Cryptococcus neoformans of Japan by restriction fragment length polymorphism.

Previous epidemiological studies of Cryptococcus neoformans infection in Japan showed that only C. neoformans var. neoformans is present and serotype A is the most common with frequencies in excess of 95%. A DNA fingerprinting method, using a genomic DNA probe (UT-4p), has become available recently which discriminates between individual isolates in a population that are morphologically and serologically indistinguishable. Fifty-two serotype A isolates of C. neoformans were obtained from three different institutions (in Nagasaki, Chiba, and Tokyo) in Japan. Only two of these strains were isolated from AIDS patients and one from pigeon excreta. Of the nine reported finger-printing patterns in serotype A, only three types (IV, V and VII) were observed in Japanese isolates. Pattern IV was almost exclusively observed in Nagasaki isolates (21/22) with only one of pattern VII. In Chiba, however, patterns VII and IV appeared to be equally distributed. In Tokyo, patterns IV and V (which included two isolates from AIDS patients) were observed at similar frequencies. Restriction fragment length polymorphism analysis of four isolates of serotype AD showed a typical serotype A pattern which also contained a serotype D-specific band. This finding suggests the independence of serotype AD. These data could enhance the survey of the epidemiology of cryptococcosis.