Resistance to fluconazole and cross-resistance to amphotericin B in Candida albicans from AIDS patients caused by defective sterol delta5,6-desaturation

FEBS Lett. 1997 Jan 2;400(1):80-2. doi: 10.1016/s0014-5793(96)01360-9.


Fluconazole resistance occurs in > 10% of cases of candidosis during the late stages of AIDS. We show here in two clinical isolates that resistance was caused by defective sterol delta5,6-desaturation. This altered the type of sterol accumulating under fluconazole treatment from 14alpha-methylergosta-8,24(28)-dien-3beta,6alpha -diol to 14alpha-methylfecosterol which is capable of supporting growth. A consequence of this mechanism of azole resistance is that an absence of ergosterol causes cross-resistance to the other major antifungal agent available, amphotericin B. The results also show that growth arrest after fluconazole treatment of C. albicans in clinical conditions is caused by 14alpha-methylergosta-8,24(28)-dien-3beta,6alpha -diol accumulation.

MeSH terms

  • Acquired Immunodeficiency Syndrome / microbiology*
  • Adult
  • Amphotericin B / pharmacology*
  • Antifungal Agents / pharmacology*
  • Candida albicans / drug effects*
  • Candida albicans / metabolism
  • Drug Resistance, Microbial
  • Female
  • Fluconazole / pharmacology*
  • Humans
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Oxidoreductases / metabolism*
  • Sterols / metabolism*


  • Antifungal Agents
  • Sterols
  • Amphotericin B
  • Fluconazole
  • Oxidoreductases
  • sterol delta-5 desaturase