Multicenter comparative evaluation of six commercial systems and the National Committee for Clinical Laboratory Standards M27-A broth microdilution method for fluconazole susceptibility testing of Candida species

Giulia Morace, G. Amato, F. Bistoni, G. Fadda, P. Marone, M. T. Montagna, S. Oliveri, L. Polonelli, R. Rigoli, I. Mancuso, S. La Face, L. Masucci, L. Romano, C. Napoli, D. Tatò, M. G. Buscema, C. M C Belli, M. M. Piccirillo, S. Conti, S. CovanF. Fanti, C. Cavanna, F. D'Alò, L. Pitzurra

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Abstract

Fluconazole susceptibility among 800 clinical Candida isolates (60% C. albicans) and two control strains (C. krusei ATCC 6258 and C. parapsilosis ATCC 22019) was tested with the NCCLS M27-A method (gold standard) and six commercial products (Candifast, disk, Etest, Fungitest, Integral System Yeasts, and Sensititre Yeast-One). Results were classified as susceptible, susceptible-dose dependent, or resistant using M27-A breakpoints or, for Fungitest, Integral System Yeasts, and Candifast, as susceptible, intermediate, or resistant, according to the manufacturers' instructions. Concordance with NCCLS M27-A results was analyzed with the X2 test. Intra- and interlaboratory reproducibility was also evaluated. NCCLS M27-A (90.1%), Etest (93.1%), Sensititre YeastOne (93.1%), disk (96.7%), Fungitest (92.6%), Integral System Yeasts (40.6%), and Candifast (6.0%) classified the indicated percentages of C. albicans isolates as susceptible. Among non-C. albicans strains, the percentages of susceptible isolates were as follows: NCCLS M27-A, 74.0%; Etest, 83.8%; Sensititre YeastOne, 64.1%; disk, 60.6%; Fungitest, 76.6%; Integral System Yeasts, 28.3%; and Candifast, 27.4%. All methods except Candifast and Integral System Yeasts showed good agreement with NCCLS M27-A results for both C albicans and non-C. albicans isolates. Intralaboratory reproducibility was excellent for NCCLS M27-A, Etest, Sensititre YeastOne, disk, and Fungitest (88 to 91%). Similar results emerged from the interlaboratory reproducibility evaluation. Our findings indicate that some commercial methods can be useful for fluconazole susceptibility testing of clinical Candida isolates. Those characterized by a lack of medium standardization and/or objective interpretative criteria should be avoided. Particular caution is necessary when testing is being done for clinical and epidemiological purposes.

Original languageEnglish
Pages (from-to)2953-2958
Number of pages6
JournalJournal of Clinical Microbiology
Volume40
Issue number8
DOIs
Publication statusPublished - Aug 1 2002

ASJC Scopus subject areas

  • Microbiology (medical)
  • Microbiology

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    Morace, G., Amato, G., Bistoni, F., Fadda, G., Marone, P., Montagna, M. T., Oliveri, S., Polonelli, L., Rigoli, R., Mancuso, I., La Face, S., Masucci, L., Romano, L., Napoli, C., Tatò, D., Buscema, M. G., Belli, C. M. C., Piccirillo, M. M., Conti, S., ... Pitzurra, L. (2002). Multicenter comparative evaluation of six commercial systems and the National Committee for Clinical Laboratory Standards M27-A broth microdilution method for fluconazole susceptibility testing of Candida species. Journal of Clinical Microbiology, 40(8), 2953-2958. https://doi.org/10.1128/JCM.40.8.2953-2958.2002