, Volume 173, Issue 5–6, pp 427–433 | Cite as

Comparative Analysis of the Vitek 2 Antifungal Susceptibility System and E-test with the CLSI M27-A3 Broth Microdilution Method for Susceptibility Testing of Indian Clinical Isolates of Cryptococcus neoformans

  • Aarti Tewari
  • Bijayani Behera
  • Purva Mathur
  • Immaculata XessEmail author


The emergence of antifungal resistance among Cryptococcus neoformans isolates is a matter of great concern. The Clinical and Laboratory Standards Institute (CLSI) broth microdilution reference method (BMD) for antifungal susceptibility testing of C. neoformans is tedious and time-consuming. Consequently, there is a greater need for a reproducible in vitro susceptibility testing method for use in clinical microbiology laboratories. By random amplified polymorphic DNA analysis, the 62 Indian clinical isolates were characterized as Cryptococcus neoformans var. grubii. We evaluated the susceptibilities of these isolates for amphotericin B (AMB) and fluconazole (FLC) by two commercial techniques, i.e., Vitek 2 and E-test against the CLSI M27-A3 BMD. The essential agreement (EA) between the Vitek 2 and E-test with the reference procedure for FLC was similar (82.2%). For AMB, EA of 92 and 76% was obtained with E-test and Vitek 2. Excellent categorical agreement (CA) (98.3% and 100% by Vitek 2 and E-test, respectively) was obtained for AMB. The CA for FLC was 81 and 77.4% by Vitek 2 and E-test. We conclude that both E-test and Vitek 2 system have acceptable levels of accuracy for susceptibility testing of both the drugs. Both of them could identify fluconazole-resistant strains. Vitek 2 could be used for testing susceptibility of voriconazole and 5-flucytosine also at the same time.


Broth microdilution Categorical agreement Cryptococcus neoformans Essential agreement E-test Vitek 2 


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Aarti Tewari
    • 1
  • Bijayani Behera
    • 1
  • Purva Mathur
    • 2
  • Immaculata Xess
    • 1
    Email author
  1. 1.Department of MicrobiologyAll India Institute of Medical SciencesNew DelhiIndia
  2. 2.Department of Lab MedicineJpna Trauma Centre, All India Institute of Medical SciencesNew DelhiIndia

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