Evaluating a Flexible Workflow for Candida auris Surveillance on the AltoStar Automation System AM16 with Commercial...

Multidrug-resistant yeast Candida (Candidozyma) auris, responsible for healthcare-associated outbreaks and high mortality, is a major global health threat. Rapid and scalable molecular diagnostics is essential; however, few automated platforms can accommodate both commercial assays and laboratory-developed tests (LDTs). We evaluated the analytical and clinical performance of two real-time PCR assays for C. auris detection using the AltoStar Automation System AM16.

One assay was an in-house LDT (targeting the internal transcribed spacer region), while the other was AltoStar C. auris PCR Kit 1.5 (Altona Diagnostics) assay. An integrated workflow, which included automated nucleic acid extraction and PCR setup, was employed. Analytical performance was evaluated in terms of precision, specificity, and limit of detection (LoD) using C. auris Clades I, II, and VI. Clinical accuracy was assessed using a 36-sample panel (surveillance swabs and contrived positives) tested in parallel with the DiaSorin Simplexa C. auris Direct assay (DiaSorin Molecular LLC), with culture as the reference standard.

Both assays demonstrated excellent reproducibility, with CVs below 5%, and 100% analytical specificity. The in-house LDT showed greater sensitivity, with LoDs of 25-191 colony-forming units (CFU)/mL (1.56-12 CFU/reaction) versus 52-235 CFU/mL (3.25-15 CFU/reaction) for the Altona assay. Regarding clinical accuracy, the LDT, Altona assay, and DiaSorin assay showed 100% positive and negative agreement with the culture results (Cohen's kappa=1.00).

This is the first documented comparison of a commercial assay and an LDT on the AltoStar AM16, demonstrating the platform's flexibility, which can enhance laboratory adaptability and capacity to combat the spread of C. auris, a critical fungal pathogen.