Use of mitochondrial and ribosomal DNA polymorphisms to classify clinical and soil isolates of Histoplasma capsulatum.

We have developed an improved scheme for the classification of environmental and clinical isolates of Histoplasma capsulatum that is based on analysis of mitochondrial DNA (mtDNA) and ribosomal DNA (rDNA). Strains were initially divided into mtDNA groups according to restriction digests of whole-cell DNA and Southern hybridization with cloned mtDNA probes. Strains within a mtDNA class could be further grouped by polymorphisms in rDNA. The majority of soil and clinical isolates from the United States had identical mtDNA patterns; however, rDNA polymorphisms were common in both types of isolates. The combination of mtDNA and rDNA typing described in this report will be useful in resolving questions concerning the epidemiology of H. capsulatum infections.