Molecular Investigation of the Fatal Bloodstream Candida orthopsilosis Infection Case following Gastrectomy

Abstract

Candida orthopsilosis represents a closely related cryptic genospecies of Candida parapsilosis complex-misidentified in routine diagnostic assays. This is emerging in settings where central venous catheters, invasive medical interventions, and echinocandin treatments are most likely to be used. A 59-year-old, non-neutropenic male patient, was admitted to an intensive care unit (ICU) due to respiratory distress syndrome, following a partial gastrectomy. As a result of duodenal stump leakage, re-laparotomy was required, abdominal drains were provided and central line catheters were exchanged. Multiple isolates of Candida orthopsilosis drawn from consecutive blood cultures were identified, despite ongoing echinocandin therapy and confirmed in vitro echinocandins susceptibility of the isolated strain. Species identification was verified via ITS region sequencing. Herein, we report the well-documented-per clinical data and relevant laboratory diagnosis-first case of a bloodstream infection caused by Candida orthopsilosis in Poland.

Keywords: CBSI; Candida orthopsilosis; antifungals; candidemia.

Figure 1

Representative MSPs for clinical C. parapsilosis and C. orthopsilosis strains isolated from different body locations of 59-year-old male patient with CBSI. Mass spectra intensity displayed in arbitrary units (a.u. = 0, 1, 2, 3, 4 × 10⁴) on the y-axis, whereas mass-to-charge ratio expressed in m/z units on the x-axis; color was assigned to number of strain.

Figure 2

Biotyper PCA (principal component analysis) dendrogram clustering representative MSPs for isolates of C. orthopsilosis and C. parapsilosis with distances displayed in relative units on the y-axis; MSPs for isolates of C. orthopsilosis are clustered with MSPs for reference C. orthopsilosis ATCC 96139 and ATCC 96141. Protein similarity presented on dendrogram by means of a relative distance level between isolates included into dendrogram, normalized to a maximum value of 1000 (cut-off). All tested isolates are presented by their abbreviated species name (C. ortho and C. para) and the isolation number.

Figure 3

Phylogenetic neighbour-joining tree reflecting a genetic similarity of ITS sequences. Numbers at each branch indicate similarity percentage, expressed in bootstrap values of replicate trees in which the associated taxa clustered together in the bootstrap test (1000 replicates). The scale bar indicates 0.01 changes/site (number of differences).