Laboratory Appearance & Growth Characteristics

• On CHROMagar, colonies may appear white or pink, sometimes red or purple
• Forms a budding yeast, rarely producing short pseudohyphae
• Does not form germ tubes
• Some strains form cell aggregates, others do not
• Grows well at 40–42°C, unlike most Candida species

When to Suspect C. auris

• Increase in unidentified Candida infections in healthcare units
• Rising isolation of Candida from urine specimens
• Suspected nosocomial transmission patterns
• C. auris can be misidentified as a number of different organisms when using traditional phenotypic methods for yeast identification.:
  • VITEK 2 YST
  • API 20C
  • BD Phoenix
  • MicroScan

⚠️ requiring confirmatory testing.

Culture-Based Identification Clues

• Colony color alone is not diagnostic
• Must combine morphology with advanced identification methods
• New chromogenic media may improve detection but are not definitive

MALDI-TOF Identification

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) systems can identify C. auris if updated databases are used.

Molecular Identification Methods

• Sequencing targets.
• FDA-approved blood culture molecular tests.

PCR-Based Testing

• No FDA-approved high-throughput colonization PCR tests currently exist
• Available PCR methods vary in:
  • Sensitivity and specificity
  • Turnaround time
  • Laboratory capacity requirements
• Validation should consider clinical sample type performance