APPLICATION OF DNA TYPING METHODS AND GENETIC-ANALYSIS TO EPIDEMIOLOGY AND TAXONOMY OF SACCHAROMYCES ISOLATES

We have previously described differences in phenotype and virulence am ong clinical and nonclinical isolates of Saccharomyces. To further cha racterize these isolates, a comparison of restriction fragment length polymorphism (RFLP) patterns and genetic analysis were done, The cellu lar DNA of each of 49 clinical and 11 nonclinical isolates of Saccharo myces a-as digested with the endonuclease EcoRI, and the resultant fra gments were separated by electrophoresis. Sixty isolates were grouped on the basis of the presence (group B) or absence (group A) of a 3-kb band, Group A contained 43 isolates (35 clinical and 8 nonclinical iso lates) in 31 discernible subgroups, and group B had 17 isolates (14 cl inical and 3 nonclinical isolates) in 10 subgroups, Interestingly, six of eight known vaginal isolates were group B, with four of those six being identical, Virulence of isolates was associated with membership in group A (P = 0.03), Comparison of known members of sibling species within the genus Saccharomyces, which cannot be distinguished by stand ard biochemical tests, showed that S. paradoxus, S. bayanus, and S. ce revisiae could be differentiated by RFLP analysis. Genetic analysis of the isolates forming viable spores showed that most group A isolates were diploid and members of the species S. cerevisiae. Those group A a nd B isolates unable to form viable spores may be diploid hybrids betw een Saccharomyces species, The group B isolates that formed viable spo res were tetraploid and mag also be interspecific hybrids. Overall, cl inical isolates of Saccharomyces were very heterogeneous and exhibited little clonality, RFLP pattern analysis could be a useful method of d emonstrating transmission in patients with infection or between enviro nmental sources and patients.