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Candida krusei (Pichia kudriavzevii)

C. krusei

Morphology: Elongated yeast cells. Now classified as Pichia kudriavzevii.

Yeast

Typical drugs

  1. #1Micafungin— First-line — intrinsic fluconazole resistance.
  2. #2Caspofungin
  3. #3Voriconazole— Active against krusei; useful step-down.
  4. #4Amphotericin B (liposomal)— Reduced susceptibility — higher MICs than other species.

Empiric therapy when resistant

ALWAYS use echinocandin (or voriconazole) — never fluconazole. Liposomal amphotericin if echinocandin-resistant.

Resistance mechanisms

  • Target alteration

    Intrinsic Erg11 structural variation prevents fluconazole binding

    Example: Inherent fluconazole resistance — never use for krusei.

Resistance notes

Intrinsic fluconazole resistance. Reduced amphotericin B susceptibility (MICs higher than albicans). Also reduced flucytosine susceptibility.

Pearls

Risk factors: hematologic malignancy with prolonged fluconazole prophylaxis. Don't reach for fluconazole even if labeled "Candida" — wait for species ID.

References

  • IDSA Candidiasis Guidelines (2016)