To improve understanding of the epidemiology of cryptococcal disease, we analyzed the multilocus genotype distribution of 358Cryptococcus neoformansisolates obtained from 251 patients through active surveillance in four U.S. geographic areas from 1992 through 1994. Isolates of the predominant enzyme electrophoretic type (ET), ET-1, were recovered in significantly greater proportion from Atlanta, Ga., Houston, Tex., and all major metropolitan areas of Alabama than from San Francisco, Calif. ET-2 and ET-7 complex (serotype AD) isolates were recovered predominantly from San Francisco. ET-3 was recovered less frequently from San Francisco than from the three other locations. Thesefindings may reflect geographic differences in exposure to environ- mental strains or the identification of previously unrecognized C. neoformans clusters. Analysis by random amplified polymorphic DNA-PCR subtyping further divided 67 ET-1 isolates into 19 additional subtypes, none of which could be associated with a particular geographic region. Multiple isolates from the same patient always revealed the same multilocus enzyme electrophoresis and random amplified polymorphic DNA sub- types. No differences in subtype distribution were found when isolates from AIDS patients were compared with those from persons without or with another underlying disease, although oneC. neoformansvar.gattiiisolate was obtained from an AIDS patient. When body site distribution was analyzed, ET-4 was disproportionately recovered from skin or surface body sites. Evidence for linkage disequilibrium in this fungal population suggests that virulentC. neoformanspossesses a clonal population structure. Continued application of molec- ular subtyping methods will be useful in tracking the source, transmission, and relative virulence of differentC. neoformansstrains.

To improve understanding of the epidemiology of cryptococcal disease, we analyzed the multilocus genotype distribution of 358 Cryptococcus neoformans isolates obtained from 251 patients through active surveillance in four U.S. geographic areas from 1992 through 1994, Isolates of the predominant enzyme electrophoretic type (ET), ET-1, were recovered in significantly greater proportion from Atlanta, Ga., Houston, Tex., and all major metropolitan areas of Alabama than from San Francisco, Calif, ET-2 and ET-7 complex (serotype AD) isolates were recovered predominantly from San Francisco, ET-3 was recovered less frequently from San Francisco than from the three other locations, These findings may reflect geographic differences in exposure to environmental strains or the identification of previously unrecognized C. neoformans clusters, Analysis by random amplified polymorphic DNA-PCR subtyping further divided 67 ET-1 isolates into 19 additional subtypes, none of which could be associated with a particular geographic region, Multiple isolates from the same patient always revealed the same multilocus enzyme electrophoresis and random amplified polymorphic DNA subtypes, No differences in subtype distribution were found when isolates from AIDS patients were compared with those from persons without or with another underlying disease, although one C, neoformans var, gattii isolate was obtained from an AIDS patient, When body site distribution was analyzed, ET-4 was disproportionately recovered from skin or surface body sites, Evidence for linkage disequilibrium in this fungal population suggests that virulent C, neoformans possesses a clonal population structure, Continued application of molecular subtyping methods will be useful in tracking the source, transmission, and relative virulence of different C. neoformans strains.

To improve understanding of the epidemiology of cryptococcal disease, we analyzed the multilocus genotype distribution of 358 Cryptococcus neoformans isolates obtained from 251 patients through active surveillance in four U.S. geographic areas from 1992 through 1994. Isolates of the predominant enzyme electrophoretic type (ET), ET-1, were recovered in significantly greater proportion from Atlanta, Ga., Houston, Tex., and all major metropolitan areas of Alabama than from San Francisco, Calif. ET-2 and ET-7 complex (serotype AD) isolates were recovered predominantly from San Francisco. ET-3 was recovered less frequently from San Francisco than from the three other locations. These findings may reflect geographic differences in exposure to environmental strains or the identification of previously unrecognized C. neoformans clusters. Analysis by random amplified polymorphic DNA-PCR subtyping further divided 67 ET-1 isolates into 19 additional subtypes, none of which could be associated with a particular geographic region. Multiple isolates from the same patient always revealed the same multilocus enzyme electrophoresis and random amplified polymorphic DNA subtypes. No differences in subtype distribution were found when isolates from AIDS patients were compared with those from persons without or with another underlying disease, although one C. noeformans var. gattii isolate was obtained from an AIDS patient. When body site distribution was analyzed, ET-4 was disproportionately recovered from skin or surface body sites. Evidence for linkage disequilibrium in this fungal population suggests that virulent C. neoformans possesses a clonal population structure. Continued application of molecular subtyping methods will be useful in tracking the source, transmission, and relative virulence of different C. neoformans strains.

We evaluated multilocus enzyme electrophoresis (MEE) and random amplified polymorphic DNA (RAPD) for their usefulness in subtyping 344 Cryptococcus neoformans clinical isolates obtained from four U.S. metropolitan areas in 1992 to 1994. MEE and RAPD with five primers both discriminated between the two varieties of C. neoformans. MEE divided C. neoformans var. neoformans isolates into 15 enzyme electrophoretic subtypes (ETs) arranged in three complexes, The predominant ET 1 complex contained 10 ETs, with isolates from 70% of patients in 1 ET. RAPD with five primers further sorted this predominant ET into 19 subtypes, with 60% of isolates sorting into three RAPD types. The ET 8 MEE complex, containing three ETs, could not be divided further by RAPD. The ET 7 complex (two ETs) included isolates from all serotype AD patients. Although both MEE and RAPD identified isolates of C. neoformans var. gattii, neither distinguished between serotypes B and C. These results showed that the two C. neoformans varieties could be identified by MEE or RAPD profile as well as by biochemical methods. RAPD improved the discriminatory power of MEE for isolates within the ET 1 complex but with other ETs offered little additional sensitivity over MEE and was less sensitive than MEE with isolates of C. neoformans var. gattii. This information will be useful in identifying particular environmental sources of disease-causing exposures, in seeking clusters of cases, and in determining whether an infecting strain changes over time.