Comparative analysis of Etest and broth microdilution method (AFST-EUCAST) for trends in antifungal drug susceptibility testing of Brazilian Cryptococcus neoformans isolates

• Published in: Journal of medical microbiology Vol. 55; no. 12; pp. 1693 - 1699
• Main Authors: Dias, Amanda L. T, Matsumoto, Flavia E, Melhem, Marcia S. C, da Silva, Eriques G, Auler, Marcos E, de Siqueira, Antonio M, Paula, Claudete R
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01-12-2006; Society for General Microbiology
• Subjects: Antifungal Agents - pharmacology; Biological and medical sciences; Brazil; Cryptococcosis - microbiology; Cryptococcus neoformans; Cryptococcus neoformans - drug effects; Fundamental and applied biological sciences. Psychology; Humans; Infectious diseases; Medical sciences; Microbial Sensitivity Tests - methods; Microbiology; Miscellaneous; Mycology; Reagent Kits, Diagnostic; Sensitivity and Specificity; Brazil; Fungi; Antifungal agent; Yeast; Cryptococcus neoformans; Microbiology; Drug susceptibility test; Isolate; Fungi Imperfecti; Method; Thallophyta
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/jmm.0.46789-0

1 Departamento de Microbiologia, Laboratório de Micologia, Instituto de Ciências Biomédicas II, Universidade de São Paulo (USP), São Paulo-SP, Brazil
2 Departamento de Ciências Biológicas, Laboratório de Microbiologia, Universidade Federal de Alfenas-MG, Alfenas-MG, Brazil
3 Instituto Adolfo Lutz, São Paulo-SP, Brazil
Correspondence Claudete R. Paula crpmicol{at}uol.com.br
Received 18 June 2006
Accepted 15 August 2006
A prospective study was performed to evaluate the correlation between the proposed standard of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing (AFST-EUCAST) (document 7.1) and the commercial system Etest for determining the MICs of flucytosine, amphotericin B, fluconazole, itraconazole and voriconazole for a collection of 100 clinical and environmental isolates of Cryptococcus neoformans . The agreements among Etest MICs within ±2 log 2 dilutions of AFST-EUCAST standard MICs were greater for flucytosine, fluconazole and voriconazole (76, 78 and 88 %, respectively) than for amphotericin B (5 %), the lowest agreement, and itraconazole (67 %). Overall, the correlation coefficients were statistically significant ( P <0.05), and it is suggested that the Etest and AFST-EUCAST method are reliable alternatives and present good correlation for all drugs evaluated except amphotericin B. However, the observed differences related to MICs for susceptible, susceptible dose dependent and resistant strains between the methods suggest that it will be necessary to carry out further studies, including assessment of interlaboratory agreement and correlation of MICs by different methods with in vivo response.
Abbreviations: AFST-EUCAST, Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing; CLSI, Clinical and Laboratory Standards Institute; R, resistant; S, susceptible; S-DD, susceptible dose-dependent.