High burden of multidrug-resistant Candidozyma (formerly Candida) auris in a tertiary care haematology unit: Diagnostic pitfalls and identification of high-risk clinical areas.

Candidozyma (formerly Candida) auris is a multidrug-resistant critical priority pathogen, posing significant challenges in high-risk settings. This study was aimed to determine the proportion of C. auris among candidemia, evaluate automated antifungal susceptibility testing (AFST) against Broth Microdilution (BMD), and identify high-risk areas in a haematology unit. A prospective cross-sectional study (September 2024-September 2025) screened 3894 blood cultures in a Kolkata hospital. Isolates were identified via Vitek-2 and MALDI-TOF MS. Vitek 2 AFST results were compared with the gold-standard BMD. Spatial mapping was utilized to identify ward clustering. Excluding paediatric and non-haematology cases, the adult C. auris cohort (n = 38) was analysed (mean age 25.8 ± 11.2 years). All had haematological malignancy and neutropenia, with central venous catheters in 81.6% (n = 31). The 30-day crude mortality was 15.8% (n = 6). Diagnostically Vitek 2 demonstrated a critical 47.4% Major Error rate for Amphotericin B compared to BMD (P < 0.001), significantly overestimating resistance. Spatial mapping identified persistent environmental reservoirs around specific high-traffic beds. Vitek 2 significantly overestimates Amphotericin B resistance, necessitating BMD verification to prevent inappropriate exclusion of polyene therapy. The infection burden in young, neutropenic adult highlights a vulnerable demographic. Persistence case clustering suggests environmental fomite colonization, requiring enhanced diagnostic stewardship and targeted sporicidal decontamination in haematology units.