Laboratory Diagnosis of Yeast Infections

Abstract

The diagnosis of yeast infections has been dominated by culture-based methods and this continues in the modern medical microbiology laboratory. The germ tube test to distinguish Candida albicans and Candida dubliniensis from other yeasts remains one of the few useful morphological identification tests; otherwise, identification of yeasts depends largely on panels of sugar assimilation assays. In recent years, chromogenic agars have become popular for mixture or full identifications. Automated biochemical systems for yeast identification are gaining popularity in larger laboratories. Molecular identification has become an important approach, with sequences in rRNA genes and spacers being used in DNA sequence analysis, microarrays or peptide nucleic acid probe based fluorescent hybridisation assays. Non-culture based approaches to the diagnosis of yeast infections have been suggested as ways to improve the sensitivity and speed of a diagnosis, though currently few have been proved as sufficient and reliable alternatives to culture.