PCR-based identification and strain typing of Pichia anomala using the ribosomal intergenic spacer region IGS1

Abstract

Frequent outbreaks of Pichia anomala fungaemia in paediatric patients have warranted the development of a rapid identification system for this organism. This study describes a specific PCR-based method targeting the rRNA gene intergenic spacer region 1 (IGS1) for rapid identification of Pichia anomala isolates and characterization at the strain level. These methods of species identification and strain typing were used on 106 isolates of Pichia anomala (77 from a previously described outbreak and 29 isolated post-outbreak from the same hospital). Using conventional morphological and biochemical methods, 11 strains isolated during the outbreak were misidentified as P. anomala. BLAST analysis of sequences of internal transcribed spacer (ITS) regions of rRNA genes confirmed that they were Pichia guilliermondii (eight isolates) and Debaryomyces hansenii (three isolates). Strain typing of Pichia anomala isolates confirmed the previous finding of a point-source outbreak. The results suggest that IGS sequences and their polymorphisms could be exploited for similar typing methods in other organisms.