Journal article
Influence of Test Conditions on Antifungal Time-Kill Curve Results: Proposal for Standardized Methods
Antimicrobial agents and chemotherapy, Vol.42(5), pp.1207-1212
05/01/1998
DOI: 10.1128/AAC.42.5.1207
PMCID: PMC105779
PMID: 9593151
Abstract
This study was designed to examine the effects of antifungal carryover, agitation, and starting inoculum on the results of time-kill tests conducted with various Candida species. Two isolates each of Candida albicans, Candida tropicalis, and Candida glabrata were utilized. Test antifungal agents included fluconazole, amphotericin B, and LY303366. Time-kill tests were conducted in RPMI 1640 medium buffered with morpholinepropanesulfonic acid (MOPS) to a pH of 7.0 and incubated at 35°C. Prior to testing, the existence of antifungal carryover was evaluated at antifungal concentrations ranging from 1× to 16× MIC by four plating methods: direct plating of 10, 30, and 100 μl of test suspension and filtration of 30 μl of test suspension through a 0.45-μm-pore-size filter. Time-kill curves were performed with each isolate at drug concentrations equal to 2× MIC, using a starting inoculum of approximately 105 CFU/ml, and incubated with or without agitation. Last, inoculum experiments were conducted over three ranges of starting inocula: 5 × 102 to 1 × 104, >1 × 104 to 1 × 106, and >1 × 106 to 1 × 108 CFU/ml. Significant antifungal carryover (>25% reduction in CFU/milliliter from the control value) was observed with amphotericin B and fluconazole; however, carryover was eliminated with filtration. Agitation did not appreciably affect results. The starting inoculum did not significantly affect the activity of fluconazole or amphotericin B; however, the activity of LY303366 may be influenced by the starting inoculum. Before antifungal time-kill curve methods are routinely employed by investigators, methodology should be scrutinized and standardized procedures should be developed.
Details
- Title: Subtitle
- Influence of Test Conditions on Antifungal Time-Kill Curve Results: Proposal for Standardized Methods
- Creators
- Michael E Klepser - University of IowaErika J Ernst - University of IowaRussell E Lewis - University of IowaMichael E Ernst - University of IowaMichael A Pfaller - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Antimicrobial agents and chemotherapy, Vol.42(5), pp.1207-1212
- DOI
- 10.1128/AAC.42.5.1207
- PMID
- 9593151
- PMCID
- PMC105779
- NLM abbreviation
- Antimicrob Agents Chemother
- ISSN
- 0066-4804
- eISSN
- 1098-6596
- Publisher
- American Society for Microbiology
- Language
- English
- Date published
- 05/01/1998
- Academic Unit
- Epidemiology; Pathology; Family and Community Medicine; Pharmacy Practice and Science
- Record Identifier
- 9984297351102771
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