Testing to Detect Candida auris Colonisation After Intrahospital Transfer From an Endemic Area, a Prospective Observational Study

BACKGROUND: Current international guidelines lack clear recommendations on the management of non-colonised patients undergoing intra-hospital transfer from the ward in which horizontal transmission of Candida auris is known to occur (defined as endemic for Candida auris) to wards with no horizontal transmission detected (defined as non-endemic wards), particularly regarding the timing and number of screening swabs needed to exclude colonisation. METHODS: Single-center prospective observational study at a tertiary-care hospital in Genoa, Italy, including adults transferred from the C. auris endemic-ICU (eICU) to non-endemic wards between January and December 2024. Patients who tested negative for C. auris colonisation both at eICU admission and at transfer, and who had ≥ 1 screening swab performed post-transfer, were included. Swabs (bilateral axilla/groin) were performed on Days 0-1, 2-3 after transfer, and then weekly, and tested for C. auris with real-time PCR. Patients were considered sufficiently screened to exclude colonisation if they underwent ≥ 2 swabs within the first 4 weeks after transfer. RESULTS: Among 462 patients transferred from the eICU, 440 (95.2%) were non-colonised. Among them, 275 (62.5%) met inclusion criteria, and 208 (75.6%) were considered sufficiently screened. C. auris colonisation was detected in 34/208 (16.3%) patients, with 21 (61.8%) positive in the first post-transfer swab. Among 99 patients who had a negative result of a swab performed within 1 day before transfer, 7 (7.1%) resulted later positive. C. auris candidemia occurred in 4/34 (11.8%) patients with colonisation detected post-transfer, compared to 1/35 (2.9%) patients found colonised during eICU stay, and none occurred in non-colonised individuals. CONCLUSIONS: A single negative screening test at eICU discharge is insufficient to exclude colonisation, even if performed within 24 h from transfer. Repeated screening, ideally within the first 2 weeks post-transfer, is essential to detect colonisation and prevent further C. auris transmission.