Molecular epidemiology of Candida parapsilosis sepsis from outbreak investigations in neonatal intensive care units

The DNA probe, Cp3-13, was used in a Southern blot assay for genotyping Candida parapsilosis (CP) from 3 fungemia outbreaks in neonatal intensive care units (NICUs) in the southeastern U.S. Genotyping, in 2 outbreaks, supplied evidence of horizontal transmission of CP. In the third outbreak, bloodstream isolates (BSIs) of 2 genotypes circulated in the NICU, one was shared by a BSI and a healthcare worker's hand culture. A fourth cluster of recurrent episodes of fungemia occurred in outpatients of a children's hospital receiving total parenteral nutrition (TPN) at home. Each child was infected with a different CP genotype which persisted during recurrences. These genotypes were included in a dendrogram from a CDC population-based surveillance for candidemia consisting of 73 clone-corrected Cp3-13 genotypes (overall SAB = 0.36). Analysis revealed a cluster of 11 genotypes (mean SAB = 0.66) including 3 pairs with identical hybridization profiles. A second cluster of 8 genotypes contained clones from 3 outbreaks (mean SAB = 0.76) but no clustering of genotypes specific for neonates was identified. No decreased susceptibility to azole and polyene antifungal agents was detected in this collection of CP. The frequent occurrence of transmission of CP in this vulnerable population underlines the relevance of Cp3-13 subtyping to investigate suspected transmission and persistence of CP strains in the NICU.