Microsatellite typing as a new tool for identification of Saccharomyces cerevisiae strains

Since Saccharomyces cerevisiae appears to be an emerging pathogen, there is a need for a valuable molecular marker able to distinguish among strains. In this work, we investigated the potential value of microsatellite length polymorphism,vith a panel of 91 isolates, including 41 clinical isolates, 1 4 laboratory strains, and 28 strains with industrial relevance. Testing sev en polymorphic regions (five trinucleotide repeats and two dinucleotide rep eats) in a subgroup of 58 unrelated strains identified a total of 69 allele s (6 to 13 per locus) giving 52 different patterns with a discriminatory po wer of 99.03%. We found a cluster of clinical isolates sharing their genoty pe with a bakery strain, suggesting a digestive colonization following inge stion of this strain with diet. With the exception of this duster of isolat es and isolates collected from the same patient or from patients treated wi th Saccharomyces boulardii, all clinical isolates gave different and unique patterns. The genotypes are stable, and the method is reproducible. The po ssibility to make the method portable is of great interest for further stud ies using this technique. This work shows the possibility to readily identi fy S. boulardii (a strain increasingly isolated from invasive infections) u sing a unique and specific microsatellite allele.