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. 1973 Oct;4(4):392–395. doi: 10.1128/aac.4.4.392

Variables Influencing Susceptibility Testing of Cryptococcus neoformans to 5-Fluorocytosine

Edward R Block 1, Anne E Jennings 1, John E Bennett 1
PMCID: PMC444565  PMID: 4598611

Abstract

The minimum inhibitory concentration (MIC) of 5-fluorocytosine (5-FC) was determined for 65 isolates of Cryptococcus neoformans by using a twofold serial tube dilution method. The MIC was profoundly influenced by incubation temperature, inoculum size, and duration of incubation. By using a standard set of test conditions, 100% of 49 pretreatment isolates of C. neoformans were susceptible to 10 μg of 5-FC per ml or less, and 9 (56%) of 16 isolates recovered during or after 5-FC therapy were massively drug resistant (MIC > 320 μg/ml). With the standard test conditions recommended here, the tube dilution method was found to be both accurate and reproducible, and the results correlated with the treatment status of patients.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Block E. R., Jennings A. E., Bennett J. E. 5-fluorocytosine resistance in Cryptococcus neoformans. Antimicrob Agents Chemother. 1973 Jun;3(6):649–656. doi: 10.1128/aac.3.6.649. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Marks M. I., Eickhoff T. C. Application of four methods to the study of the susceptibility of yeast to 5-fluorocytosine. Antimicrob Agents Chemother (Bethesda) 1970;10:491–493. doi: 10.1128/AAC.10.3.491. [DOI] [PubMed] [Google Scholar]
  3. Normark S., Schönebeck J. In vitro studies of 5-fluorocytosine resistance in Candida albicans and Torulopsis glabrata. Antimicrob Agents Chemother. 1972 Sep;2(3):114–121. doi: 10.1128/aac.2.3.114. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Shadomy S. Further in vitro studies with 5-fluorocytosine. Infect Immun. 1970 Oct;2(4):484–488. doi: 10.1128/iai.2.4.484-488.1970. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Shadomy S. In vitro studies with 5-fluorocytosine. Appl Microbiol. 1969 Jun;17(6):871–877. doi: 10.1128/am.17.6.871-877.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Shadomy S., Kirchoff C. B., Ingroff A. E. In vitro activity of 5-fluorocytosine against Candida and Torulopsis species. Antimicrob Agents Chemother. 1973 Jan;3(1):9–14. doi: 10.1128/aac.3.1.9. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Shadomy S., Shadomy H. J., McCay J. A., Utz J. P. In vitro susceptibility of Cryptococcus neoformans to amphotericin B, hamycin, and 5-fluorocytosine. Antimicrob Agents Chemother (Bethesda) 1968;8:452–460. [PubMed] [Google Scholar]
  8. Steer P. L., Marks M. I., Klite P. D., Eickhoff T. C. 5-fluorocytosine: an oral antifungal compound. A report on clinical and laboratory experience. Ann Intern Med. 1972 Jan;76(1):15–22. doi: 10.7326/0003-4819-76-1-15. [DOI] [PubMed] [Google Scholar]
  9. Toala P., Schroeder S. A., Daly A. K., Finland M. Candida at Boston City Hospital. Clinical and epidemiological characteristics and susceptibility to eight antimicrobial agents. Arch Intern Med. 1970 Dec;126(6):983–989. doi: 10.1001/archinte.126.6.983. [DOI] [PubMed] [Google Scholar]
  10. Vandevelde A. G., Mauceri A. A., Johnson J. E., 3rd 5-fluorocytosine in the treatment of mycotic infections. Ann Intern Med. 1972 Jul;77(1):43–51. doi: 10.7326/0003-4819-77-1-43. [DOI] [PubMed] [Google Scholar]

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