Effects of Treated versus Untreated Polystyrene on Caspofungin in Vitro Activity against Candida Species

Annette W. Fothergill, Dora I. McCarthy, Mohammad T. Albataineh, Carmita Sanders, Maria McElmeel, Nathan Wiederhold

Research output: Contribution to journalArticle

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Abstract

Significant interlaboratory variability is observed in testing the caspofungin susceptibility of Candida species by both the CLSI and EUCAST broth microdilution methodologies. We evaluated the influence of treated versus untreated polystyrene microtiter trays on caspofungin MICs using 209 isolates of four Candida species, including 16 C. albicans and 11 C. glabrata isolates with defined FKS mutations. Caspofungin MICs were also determined using the commercially available YeastOne and Etest assays and 102 isolates. All C. glabrata isolates had caspofungin MICs of>0.5 g/ml, the clinical breakpoint for caspofungin resistance in this species, measured using trays made of treated polystyrene, regardless of the FKS status. In contrast, susceptible isolates could readily be distinguished from resistant/non-wild-type isolates when caspofungin MICs were measured using untreated polystyrene trays and both the YeastOne and Etest assays. Similar results were also observed for C. krusei isolates, as all isolates had caspofungin MICs above the threshold for resistance measured using treated polystyrene trays. In contrast, C. albicans isolates could be correctly identified as susceptible or resistant when caspofungin MICs were measured with treated or untreated trays and with the YeastOne and Etest assays. MICs falsely elevated above the resistance breakpoint were also not observed for C. tropicalis isolates. These results demonstrated that the use of treated polystyrene may be one factor that leads to falsely elevated caspofungin in vitro susceptibility results and that this may also be a greater issue for some Candida species than for others.

Original languageEnglish (US)
Pages (from-to)734-738
Number of pages5
JournalJournal of Clinical Microbiology
Volume54
Issue number3
DOIs
StatePublished - Mar 1 2016

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caspofungin
Polystyrenes
Candida
Disk Diffusion Antimicrobial Tests
In Vitro Techniques

ASJC Scopus subject areas

  • Microbiology (medical)

Cite this

Effects of Treated versus Untreated Polystyrene on Caspofungin in Vitro Activity against Candida Species. / Fothergill, Annette W.; McCarthy, Dora I.; Albataineh, Mohammad T.; Sanders, Carmita; McElmeel, Maria; Wiederhold, Nathan.

In: Journal of Clinical Microbiology, Vol. 54, No. 3, 01.03.2016, p. 734-738.

Research output: Contribution to journalArticle

Fothergill, Annette W. ; McCarthy, Dora I. ; Albataineh, Mohammad T. ; Sanders, Carmita ; McElmeel, Maria ; Wiederhold, Nathan. / Effects of Treated versus Untreated Polystyrene on Caspofungin in Vitro Activity against Candida Species. In: Journal of Clinical Microbiology. 2016 ; Vol. 54, No. 3. pp. 734-738.
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