Molecular ambiguities in hospital surveillance: Hyphopichia burtonii mislabelled as Candida auris by polymerase chain reaction and selective media.

BACKGROUND

Accurate environmental surveillance of Candida auris is critical for infection control but remains hampered by diagnostic limitations regarding environmental yeasts.

METHODS

This study evaluated screening methods in a hospital in Southern Brazil by analyzing 52 high-touch surface samples, specifically investigating a yeast strain isolated from a patient bed rail through selective growth (40 °C, 10% NaCl), susceptibility testing, biochemical assays (API 20C), VITEK® MS, Bruker MALDI-TOF MS, endpoint PCR, and ITS sequencing, supplemented by in-silico genomic analysis.

RESULTS

The isolate mimicked C. auris by growing under selective conditions, exhibiting high fluconazole resistance (MIC: 128 μg/mL), and producing a specific PCR amplification band (~163 bp); furthermore, while API 20C and VITEK® MS misidentified it as C. guilliermondii or C. lusitaniae/haemulonii, Bruker MALDI-TOF and ITS sequencing correctly identified it as Hyphopichia burtonii, with in-silico analysis revealing over 900 conserved primer binding sites in its rDNA array.

CONCLUSIONS

These findings demonstrate that reliance on phenotypic traits and endpoint PCR can lead to serious diagnostic errors due to conserved domains in environmental species, highlighting the need for genetic sequencing in surveillance protocols to ensure accurate epidemiological data.