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. 1997 Mar;41(3):535–539. doi: 10.1128/aac.41.3.535

Reversible fluconazole resistance in Candida albicans: a potential in vitro model.

H M Calvet 1, M R Yeaman 1, S G Filler 1
PMCID: PMC163746  PMID: 9055988

Abstract

To study the development and potential mechanisms of antifungal resistance in relation to antifungal exposure, reversible fluconazole resistance was examined in vitro. Candida albicans ATCC 36082 blastospores were passed in liquid yeast nitrogen base medium containing either 4, 8, 16, or 128 micrograms of fluconazole per ml, and susceptibility testing was performed after each passage. High-level fluconazole resistance (50% inhibitory concentration, > 256 micrograms/ml) developed in the isolates after serial passage in medium containing 8, 16, or 128 micrograms of fluconazole per ml, but not in isolates passed in 4 micrograms of fluconazole per ml. Reduced susceptibility was noted within four to seven passages, which was equivalent to 14 to 19 days of exposure to the drug. However, all isolates returned to the susceptible phenotype after 8 to 15 passages in medium lacking the drug; thus, fluconazole resistance was reversible in vitro. In vivo, organisms retained the resistant phenotype after a single passage in the rabbit model of infective endocarditis. Restriction digest profiles and karyotypic analysis of the parent strain and selected fluconazole-resistant and -susceptible isolates from each group were identical. Investigations into the molecular mechanisms of this reversible resistance failed to reveal increased accumulation of mRNA for 14 alpha-demethylase, the target enzyme for fluconazole, or for the candidal multidrug transporters CDR1 and BENr. This process of continuous in vitro exposure to antifungal drug may be useful as a model for studying the effects of different antifungal agents and dosing regimens on the development of resistance and for defining the mechanism(s) of reversible resistance.

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Selected References

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  1. Athar M. A., Winner H. I. The development of resistance by candida species to polyene antibiotics in vitro. J Med Microbiol. 1971 Nov;4(4):505–517. doi: 10.1099/00222615-4-4-505. [DOI] [PubMed] [Google Scholar]
  2. Baily G. G., Perry F. M., Denning D. W., Mandal B. K. Fluconazole-resistant candidosis in an HIV cohort. AIDS. 1994 Jun;8(6):787–792. doi: 10.1097/00002030-199406000-00010. [DOI] [PubMed] [Google Scholar]
  3. Branchini M. L., Pfaller M. A., Rhine-Chalberg J., Frempong T., Isenberg H. D. Genotypic variation and slime production among blood and catheter isolates of Candida parapsilosis. J Clin Microbiol. 1994 Feb;32(2):452–456. doi: 10.1128/jcm.32.2.452-456.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Cameron M. L., Schell W. A., Bruch S., Bartlett J. A., Waskin H. A., Perfect J. R. Correlation of in vitro fluconazole resistance of Candida isolates in relation to therapy and symptoms of individuals seropositive for human immunodeficiency virus type 1. Antimicrob Agents Chemother. 1993 Nov;37(11):2449–2453. doi: 10.1128/aac.37.11.2449. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Chavanet P., Lopez J., Grappin M., Bonnin A., Duong M., Waldner A., Buisson M., Camerlynck P., Portier H. Cross-sectional study of the susceptibility of Candida isolates to antifungal drugs and in vitro-in vivo correlation in HIV-infected patients. AIDS. 1994 Jul;8(7):945–950. doi: 10.1097/00002030-199407000-00011. [DOI] [PubMed] [Google Scholar]
  6. Ghannoum M. A., Ibrahim A. S., Fu Y., Shafiq M. C., Edwards J. E., Jr, Criddle R. S. Susceptibility testing of Cryptococcus neoformans: a microdilution technique. J Clin Microbiol. 1992 Nov;30(11):2881–2886. doi: 10.1128/jcm.30.11.2881-2886.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. He X., Tiballi R. N., Zarins L. T., Bradley S. F., Sangeorzan J. A., Kauffman C. A. Azole resistance in oropharyngeal Candida albicans strains isolated from patients infected with human immunodeficiency virus. Antimicrob Agents Chemother. 1994 Oct;38(10):2495–2497. doi: 10.1128/aac.38.10.2495. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Hitchcock C. A., Barrett-Bee K. J., Russell N. J. The lipid composition and permeability to azole of an azole- and polyene-resistant mutant of Candida albicans. J Med Vet Mycol. 1987 Feb;25(1):29–37. doi: 10.1080/02681218780000041. [DOI] [PubMed] [Google Scholar]
  9. Holt R. J., Newman R. L. Laboratory assessment of the antimycotic drug clotrimazole. J Clin Pathol. 1972 Dec;25(12):1089–1097. doi: 10.1136/jcp.25.12.1089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Iwata K. Drug resistance in human pathogenic fungi. Eur J Epidemiol. 1992 May;8(3):407–421. doi: 10.1007/BF00158576. [DOI] [PubMed] [Google Scholar]
  11. Johnson E. M., Warnock D. W., Luker J., Porter S. R., Scully C. Emergence of azole drug resistance in Candida species from HIV-infected patients receiving prolonged fluconazole therapy for oral candidosis. J Antimicrob Chemother. 1995 Jan;35(1):103–114. doi: 10.1093/jac/35.1.103. [DOI] [PubMed] [Google Scholar]
  12. Kelly S. L., Lamb D. C., Corran A. J., Baldwin B. C., Kelly D. E. Mode of action and resistance to azole antifungals associated with the formation of 14 alpha-methylergosta-8,24(28)-dien-3 beta,6 alpha-diol. Biochem Biophys Res Commun. 1995 Feb 27;207(3):910–915. doi: 10.1006/bbrc.1995.1272. [DOI] [PubMed] [Google Scholar]
  13. Langford C. J., Gallwitz D. Evidence for an intron-contained sequence required for the splicing of yeast RNA polymerase II transcripts. Cell. 1983 Jun;33(2):519–527. doi: 10.1016/0092-8674(83)90433-6. [DOI] [PubMed] [Google Scholar]
  14. Millon L., Manteaux A., Reboux G., Drobacheff C., Monod M., Barale T., Michel-Briand Y. Fluconazole-resistant recurrent oral candidiasis in human immunodeficiency virus-positive patients: persistence of Candida albicans strains with the same genotype. J Clin Microbiol. 1994 Apr;32(4):1115–1118. doi: 10.1128/jcm.32.4.1115-1118.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Odds F. C. Resistance of yeasts to azole-derivative antifungals. J Antimicrob Chemother. 1993 Apr;31(4):463–471. doi: 10.1093/jac/31.4.463. [DOI] [PubMed] [Google Scholar]
  16. Rex J. H., Pfaller M. A., Barry A. L., Nelson P. W., Webb C. D. Antifungal susceptibility testing of isolates from a randomized, multicenter trial of fluconazole versus amphotericin B as treatment of nonneutropenic patients with candidemia. NIAID Mycoses Study Group and the Candidemia Study Group. Antimicrob Agents Chemother. 1995 Jan;39(1):40–44. doi: 10.1128/aac.39.1.40. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Sangeorzan J. A., Bradley S. F., He X., Zarins L. T., Ridenour G. L., Tiballi R. N., Kauffman C. A. Epidemiology of oral candidiasis in HIV-infected patients: colonization, infection, treatment, and emergence of fluconazole resistance. Am J Med. 1994 Oct;97(4):339–346. doi: 10.1016/0002-9343(94)90300-x. [DOI] [PubMed] [Google Scholar]
  18. Sanglard D., Kuchler K., Ischer F., Pagani J. L., Monod M., Bille J. Mechanisms of resistance to azole antifungal agents in Candida albicans isolates from AIDS patients involve specific multidrug transporters. Antimicrob Agents Chemother. 1995 Nov;39(11):2378–2386. doi: 10.1128/aac.39.11.2378. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Vanden Bossche H., Marichal P., Odds F. C. Molecular mechanisms of drug resistance in fungi. Trends Microbiol. 1994 Oct;2(10):393–400. doi: 10.1016/0966-842x(94)90618-1. [DOI] [PubMed] [Google Scholar]
  20. Voss A., Hollis R. J., Pfaller M. A., Wenzel R. P., Doebbeling B. N. Investigation of the sequence of colonization and candidemia in nonneutropenic patients. J Clin Microbiol. 1994 Apr;32(4):975–980. doi: 10.1128/jcm.32.4.975-980.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Witt M. D., Bayer A. S. Comparison of fluconazole and amphotericin B for prevention and treatment of experimental Candida endocarditis. Antimicrob Agents Chemother. 1991 Dec;35(12):2481–2485. doi: 10.1128/aac.35.12.2481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. vanden Bossche H., Marichal P., Odds F. C., Le Jeune L., Coene M. C. Characterization of an azole-resistant Candida glabrata isolate. Antimicrob Agents Chemother. 1992 Dec;36(12):2602–2610. doi: 10.1128/aac.36.12.2602. [DOI] [PMC free article] [PubMed] [Google Scholar]

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