Molecular and Epidemiological Characterization of Vaginal Saccharomyces cerevisiae Isolates

ABSTRACT

Although vaginitis caused by Saccharomyces cerevisiaeis extremely rare, in recent years we have experienced an increasing frequency of S. cerevisiae isolation from the vaginas of fertile-age women. In order to investigate the epidemiology of these vaginal infections, a total of 40 isolates of S. cerevisiaederived from symptomatic and asymptomatic women were characterized by two DNA typing approaches, named ribosomal DNA (rDNA) hybridization and Ty917 hybridization, based on the Southern blotting technique. After transfer, the polymorphic DNA restriction fragments were hybridized with the entire repeat of S. cerevisiaerDNA for one method and with the entire sequence of the Ty917 retrotransposon for the other. After elaboration with computer-assisted analysis, the results of each method showed that Ty917 hybridization is endowed with a discriminatory power higher than that of rDNA hybridization. With the Ty917 hybridization method, all of the S. cerevisiae isolates tested appeared very heterogeneous, with the exception of those collected from individual patients with recurrent vaginitis. This allowed us to exclude a possible common source of infection while the high relatedness among S. cerevisiaesequential isolates from recurrent-vaginitis patients could suggest a pattern of relapse rather than frequent reinfection.