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. 1995 Nov;39(11):2459–2465. doi: 10.1128/aac.39.11.2459

In vitro determination of optimal antifungal combinations against Cryptococcus neoformans and Candida albicans.

M A Ghannoum 1, Y Fu 1, A S Ibrahim 1, L A Mortara 1, M C Shafiq 1, J E Edwards Jr 1, R S Criddle 1
PMCID: PMC162965  PMID: 8585726

Abstract

There is currently no rapid, reliable, and reproducible in vitro technique to describe the growth-inhibitory interactions of antifungal drug combinations over a wide range of drug concentrations. We have developed a microdilution plate assay that was used to determine optimal drug combinations and concentrations of one-, two-, and three-drug regimens of amphotericin B (AmphB), fluconazole (FLU), and 5-fluorocytosine (5FC) for growth inhibition of three isolates each of Cryptococcus neoformans and Candida albicans. These growth inhibition data were then used in a multifactorial design technique to (i) generate contour and surface response plots to aid visual interpretation and (ii) develop mathematical equations describing the growth responses of the fungi to a wide range of antifungal concentrations and ratios. Our data indicated that (i) antifungal drug-drug interactions affecting yeast growth are complex functions of the drugs used in combination, their absolute concentrations, and also their relative (proportional) concentrations; (ii) AmphB-FLU combinations had additive effects against C. albicans over wide concentration ranges for each agent but were indifferent (i.e., were less than additive) in their inhibitory effect on C. neoformans; (iii) other two-drug combinations (FLU-5FC or AmphB-5FC) had indifferent effects on the growth of both fungi; and (iv) three-drug combinations (AmphB-FLU-5FC) showed an additive inhibitory effect on the growth of both C. albicans and C. neoformans. The finding that no antagonism was observed in combinations employing AmphB and FLU in this in vitro model is of critical importance since it argues against the current theoretical concept, based on the individual drug's mode of action, of antagonism between these two drugs. These microdilution techniques provide a method to determine rational regimens of antifungal agents in multidrug combinations for future testing to correlate in vitro activity with in vivo response. The use of this approach has made the evaluation of complex antifungal drug-drug interactions possible and provided important new information to the evolving field of antifungal drug combination.

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Selected References

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  1. Allendoerfer R., Marquis A. J., Rinaldi M. G., Graybill J. R. Combined therapy with fluconazole and flucytosine in murine cryptococcal meningitis. Antimicrob Agents Chemother. 1991 Apr;35(4):726–729. doi: 10.1128/aac.35.4.726. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bennett J. E., Dismukes W. E., Duma R. J., Medoff G., Sande M. A., Gallis H., Leonard J., Fields B. T., Bradshaw M., Haywood H. A comparison of amphotericin B alone and combined with flucytosine in the treatment of cryptoccal meningitis. N Engl J Med. 1979 Jul 19;301(3):126–131. doi: 10.1056/NEJM197907193010303. [DOI] [PubMed] [Google Scholar]
  3. Berenbaum M. C. A method for testing for synergy with any number of agents. J Infect Dis. 1978 Feb;137(2):122–130. doi: 10.1093/infdis/137.2.122. [DOI] [PubMed] [Google Scholar]
  4. 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]
  5. Ghannoum M. A., Motawy M. S., Abu Hatab M. A., Ibrahim A. S., Criddle R. S. Multifactorial analysis of effects of interactions among antifungal and antineoplastic drugs on inhibition of Candida albicans growth. Antimicrob Agents Chemother. 1989 May;33(5):717–725. doi: 10.1128/aac.33.5.717. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Goodman J. L., Winston D. J., Greenfield R. A., Chandrasekar P. H., Fox B., Kaizer H., Shadduck R. K., Shea T. C., Stiff P., Friedman D. J. A controlled trial of fluconazole to prevent fungal infections in patients undergoing bone marrow transplantation. N Engl J Med. 1992 Mar 26;326(13):845–851. doi: 10.1056/NEJM199203263261301. [DOI] [PubMed] [Google Scholar]
  7. Horn R., Wong B., Kiehn T. E., Armstrong D. Fungemia in a cancer hospital: changing frequency, earlier onset, and results of therapy. Rev Infect Dis. 1985 Sep-Oct;7(5):646–655. doi: 10.1093/clinids/7.5.646. [DOI] [PubMed] [Google Scholar]
  8. Kong X. B., Zhu Q. Y., Ruprecht R. M., Watanabe K. A., Zeidler J. M., Gold J. W., Polsky B., Armstrong D., Chou T. C. Synergistic inhibition of human immunodeficiency virus type 1 replication in vitro by two-drug and three-drug combinations of 3'-azido-3'-deoxythymidine, phosphonoformate, and 2',3'-dideoxythymidine. Antimicrob Agents Chemother. 1991 Oct;35(10):2003–2011. doi: 10.1128/aac.35.10.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Larsen R. A., Leal M. A., Chan L. S. Fluconazole compared with amphotericin B plus flucytosine for cryptococcal meningitis in AIDS. A randomized trial. Ann Intern Med. 1990 Aug 1;113(3):183–187. doi: 10.7326/0003-4819-113-3-183. [DOI] [PubMed] [Google Scholar]
  10. McKinlay M. A., Rossmann M. G. Rational design of antiviral agents. Annu Rev Pharmacol Toxicol. 1989;29:111–122. doi: 10.1146/annurev.pa.29.040189.000551. [DOI] [PubMed] [Google Scholar]
  11. Medoff G., Comfort M., Kobayashi G. S. Synergistic action of amphotericin B and 5-fluorocytosine against yeast-like organisms. Proc Soc Exp Biol Med. 1971 Nov;138(2):571–574. doi: 10.3181/00379727-138-35943. [DOI] [PubMed] [Google Scholar]
  12. Powderly W. G., Saag M. S., Cloud G. A., Robinson P., Meyer R. D., Jacobson J. M., Graybill J. R., Sugar A. M., McAuliffe V. J., Follansbee S. E. A controlled trial of fluconazole or amphotericin B to prevent relapse of cryptococcal meningitis in patients with the acquired immunodeficiency syndrome. The NIAID AIDS Clinical Trials Group and Mycoses Study Group. N Engl J Med. 1992 Mar 19;326(12):793–798. doi: 10.1056/NEJM199203193261203. [DOI] [PubMed] [Google Scholar]
  13. Prichard M. N., Prichard L. E., Shipman C., Jr Strategic design and three-dimensional analysis of antiviral drug combinations. Antimicrob Agents Chemother. 1993 Mar;37(3):540–545. doi: 10.1128/aac.37.3.540. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Prichard M. N., Shipman C., Jr A three-dimensional model to analyze drug-drug interactions. Antiviral Res. 1990 Oct-Nov;14(4-5):181–205. doi: 10.1016/0166-3542(90)90001-n. [DOI] [PubMed] [Google Scholar]
  15. Sabra R., Branch R. A. Amphotericin B nephrotoxicity. Drug Saf. 1990 Mar-Apr;5(2):94–108. doi: 10.2165/00002018-199005020-00003. [DOI] [PubMed] [Google Scholar]
  16. Titsworth E., Grunberg E. Chemotherapeutic activity of 5-fluorocytosine and amphotericin B against Candida albicans in mice. Antimicrob Agents Chemother. 1973 Sep;4(3):306–308. doi: 10.1128/aac.4.3.306. [DOI] [PMC free article] [PubMed] [Google Scholar]

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