A new, rapid multiplex PCR method identifies frequent probiotic origin among clinical Saccharomyces isolates.

An increasing number of infections originating from probiotic use are reported worldwide, with the majority of such cases caused by the yeast Saccharomyces 'boulardii', a subtype of S. cerevisiae. Reliably linking infectious cases to probiotic products requires unequivocal genotyping data, however, these techniques are often time-consuming and difficult to implement in routine diagnostics. This leads to a widespread lack of genetic data regarding the origin of Saccharomyces infections. We propose a quick and reliable PCR-based protocol for the identification of S. 'boulardii' based on a combined analysis of interdelta fingerprinting and microsatellite typing. By applying various typing methods and our proposed method to the clinical yeast collection of a Hungarian hospital we show that probiotic origin is common among clinical Saccharomyces, and that the new multiplex method enables rapid and unequivocal identification of probiotic yeast infections. This method can be applied for the identification of yeast infection sources, helping decisions on probiotic use.