Quality Control Guidelines for NCCLS Broth Microdilution Susceptibility Method (M38-A document) for Four Antifungal Agents

A. V. ESPINEL-INGROFF 1, M. PFALLER 2, S. BROWN 3, M. GHANNOUM 4, E. MANAVATHU 5, L. OSTROSKY-ZEICHNER 6, M. RINALDI 7, W. SCHELL 8, T. WALSH 9

Author address: 

1 VCU Medical Center, Richmond, VA, 2 Univ. of Iowa Coll. Med., Iowa City, IA, 3 CMI, Wilsonville, OR, 4 Case Western Univ., Cleveland, OH, 5 Wayne State Univ., Detroit, MI, 6 Univ. of Texas, Houston, TX, 7 Univ. of Texas, San Antonio, TX, 8 Duke Uni

Abstract: 

Background: The NCCLS has approved a reference method (M38-A document) for antifungal susceptibility testing of filamentous fungi (moulds), but this document does not describe QC MIC limits for any antifungal agent/mould species combination. The purpose of this multicenter (8 labs.) study was to select QC isolates among 12 moulds (Aspergillus spp. [7 isolates, 4 species], Scedosporium apiospermum [2 isolates], Fusarium moniliforme, F. solani, & Paecilomyces variotii [1 isolate each) and establish MIC limits for broth microdilution tests of amphotericin B (A), itraconazole (I), posaconazole (P) & voriconazole (V). Methods: Each lab followed a standard protocol based on M38-A and M23-A2 testing guidelines. The inter- & intralaboratory reproducibility of 10 replicate tests performed for each drug/strain combination in each lab. on 10 different days were determined (48 h readings at 100% growth inhibition). Results: One lab failed QC (Candida krusei ATCC 6258 MIC limits) & their results were excluded. The following strains met the criteria for QC isolates (on-scale & > 95% interlaboratory agreement. Conclusions: These control limits will provide clinical and research laboratories the necessary assurance for their appropriate testing of mould isolates with the antifungal agents evaluated. These limits will be submitted to the NCCLS Subcommittee for review and possible approval.
2004

abstract No: 

M-1789-200

Full conference title: 

44th Interscience Conference on Antimicrobial Agents and Chemotherapy
    • ICAAC 44th