Development of amphotericin B-resistant Candida tropicalis in a patient with defective leukocyte function

Am J Med Sci. Jul-Aug 1978;276(1):77-92.


Emergence, during therapy, of fungi resistant to amphotericin B is purportedly rare, as fungi with altered cell membrane ergosterol content are considered too fragile to survive normal host defenses. Progressive amphotericin B resistance arose in a strain of Candida tropicalis isolated repeatedly from the urine of a patient with pyelonephritis. The most resistant isolate (R-2) lacked cell membrane ergosterol, the usual attachment site for amphotericin B, and was not inhibited by greater than 500 micrograms/ml of the drug. R-2 infected and killed embryonated eggs, but was unable to produce progressive renal infection in steroid-treated mice because of a reduced capacity to produce pseudomycelia. Persistent infection of the patient by this altered fungus was attributed to defective leukocyte candidacidal activity, especially marked in autologous serum, and to defective Candida-related cell-mediated immunity. A literature review suggests that amphotericin B resistance may not be as rare as many authorities have indicated. It is apparent that few laboratories routinely monitor fungi for amphotericin B susceptibility. In patients with defective antimicrobial defenses, amphotericin B-resistant fungi may survive, produce progressive infection, and require alternative chemotherapy for eradication.

Publication types

  • Case Reports
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amphotericin B / pharmacology
  • Amphotericin B / therapeutic use*
  • Animals
  • Blood Bactericidal Activity / drug effects
  • Candida / drug effects
  • Candidiasis / drug therapy*
  • Chick Embryo
  • Drug Resistance, Microbial
  • Female
  • Humans
  • Immunity, Cellular
  • Leukocytes / immunology
  • Leukocytes / physiology*
  • Male
  • Mice
  • Middle Aged
  • Pyelonephritis / microbiology
  • Pyelonephritis / urine


  • Amphotericin B