Identification and Antifungal Susceptibility Profiles of Candida haemulonii Species Complex Clinical Isolates from a Multicenter Study in China

Abstract

Candida haemulonii complex (Candida haemulonii, Candida haemulonii var. vulnera, and Candida duobushaemulonii) consists of emerging pathogens. Thirty-one isolates from 14 hospitals in China were studied for their species classification and antifungal susceptibilities. Performances of molecular (i.e., ribosomal DNA [rDNA] internal transcribed spacer [ITS] sequencing, D1/D2 sequencing, and ITS sequencer-based capillary gel electrophoresis [SCGE]) and phenotypic identification methods in species identification were compared. Twenty-six (83.9%) of 31 isolates were identified as C. haemulonii and 5 isolates were identified as C. duobushaemulonii by ITS sequencing as the reference method; results obtained by D1/D2 sequencing and ITS SCGE were concordant with those obtained by ITS sequencing for all (100%) of the isolates. All 31 isolates were identified as C. haemulonii by the Vitek matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system (bioMérieux, France), whereas the Bruker MS system (Bruker Daltoniks, Germany) correctly provided species identification for 77.4% and 100% of isolates using cutoff scores for species of ≥2.0 and ≥1.70, respectively. The Vitek 2 compact (bioMérieux) only identified 9 (29%) of 31 isolates. All isolates showed high MICs for amphotericin B (range, 2 to >8 μg/ml) and fluconazole (≥128 μg/ml) but low MICs (≤0.5 μg/ml) for the echinocandins. Our results reinforce the need for MALDI-TOF MS and/or molecular differentiation of species within the C. haemulonii complex. The multiresistant antifungal susceptibility profile of these isolates represents a challenge to therapy.