Fluconazole Resistant Candida — MFDS Part 1 MCQ

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HardMicrobiologyFluconazole Resistant CandidaMFDS Part 1

An oral Candida isolate has been identified to species level, but isolate-specific antifungal susceptibility results are not yet available. Which species identification, by itself, predicts intrinsic resistance to fluconazole rather than reduced susceptibility or possible acquired resistance?

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Correct answer: B — Candida krusei

Candida krusei is intrinsically resistant to fluconazole, so species identification alone predicts that fluconazole is an unsuitable treatment. Candida glabrata is the principal distractor: it characteristically has reduced susceptibility and may require increased exposure or alternative therapy, but it should not be described categorically as intrinsically resistant. Candida albicans, Candida tropicalis and Candida parapsilosis are generally susceptible to fluconazole, although individual isolates can develop acquired resistance. The decisive distinction is therefore intrinsic species-level resistance versus reduced or acquired susceptibility. Failure of oral candidosis to respond to fluconazole should prompt reassessment, species identification and, where appropriate, susceptibility testing.

Reference: Ranbaxy (UK) Limited, Fluconazole 150 mg Capsules: Summary of Product Characteristics, sections 4.4 and 5.1, updated 13 March 2024. https://www.medicines.org.uk/emc/product/4438/smpc