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 3 894 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 analyzed (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.