Saccharomyces cerevisiae: An Emerging and Model Pathogenic Fungus
This chapter first reviews the evidence (i. e., clinical reports and incidence) that Saccharomyces cerevisiae is an emerging opportunistic pathogen, how and why S. cerevisiae is found clinically (e.g., acquisition and host factors), and species identification and typing. The chapter describes the analysis (e.g., genetic, phenotypic, and experimental infections) of clinical S. cerevisiae isolates and clinically derived S. cerevisiae strains. In addition to making some specific comparisons of S. cerevisiae with other pathogenic fungi, the chapter describes classical genetic analysis of the ability of S. cerevisiae to survive in and kill mice. There is evidence that S. cerevisiae infections (and/or carriage) can be acquired nosocomially, through use in baking, sexually (and/or from person to person), and orally by direct ingestion. The tests used in clinical microbiology laboratories to distinguish different species of fungi, which include assimilation tests and microscopic examination, are not sufficient to distinguish the Saccharomyces sensu stricto species, that is, the taxonomically accepted biological sibling species of S. cerevisiae which include S. paradoxus, S. bayanus, S. cariocanus, S. kudriavzevii, and S. mikatae. The analysis of clinical (and nonclinical) isolates of S. cerevisiae benefits immensely from the use of sensitive, high-throughput genotyping technologies, such as the Affymetrix yeast genome arrays, that readily detect deletions, changes in gene copy numbers, and single-nucleotide polymorphisms across the entire genome.
