Aug 23, 2012 - clinical breakpoints. ⢠Chosen by taking into account the MIC distribution of a species, the modal distribution, and the inherent variability in.
8/23/2012
ANTIFUNGAL SUSCEPTIBILITY TESTING METHODS • Macrobroth dilution • Microbroth dilution • Disk diffusion • Agar diffusion
CLSI UPDATES FOR ANTIFUNGAL SUSCEPTIBILITY TESTING ANNETTE FOTHERGILL*ASSOCIATE PROFESSOR * UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER
2
CLSI (NCCLS) PUBLICATIONS
M27-A3
• 2008 – M27-A3
• Inoculum
• Third edition
• 0.5-2.5 x 104 • 0.5 McFarland at 530 nm wavelength
• 2008 – M38-A2
• Incubation
• Second edition
• 24 hours
• 2004 – M44-A
• AMB, ANID, CAS, MICA, FLU, POSA, VORI
• Approved Standard
• 48 hours
• 2010 – M51-A
• AMB, FLU, 5FC, ITRA, POS, RAV, VORI
• 72 hours
• Approved Standard
• Cryptococcus sp. – all drugs 3
M27-A3 • Drug Preparation • AMB • DMSO
• Candins • DMSO (CAS and MICA previously water)
• Azoles • DMSO (FLU previously water)
• 5FC • DMSO (previously water)
M27-A3 • End Points • AMB • 100 % Inhibition
• Candins • 50% Inhibition (24 hours ONLY)
• Azoles • 50% Inhibition
• 5FC • 50% Inhibition
1
8/23/2012
EPIDEMIOLOGICAL CUTOFF VALUES • A value used to assist with interpretation of MIC data where sufficient clinical data is not available for the purpose of establishing clinical breakpoints • Chosen by taking into account the MIC distribution of a species, the modal distribution, and the inherent variability in MIC testing methods (typically 2 dilutions above the modal MIC)
EPIDEMIOLOGICAL CUTOFF VALUES • Although the exact percent varies per publication, most agree that the wild-type strains should comprise 95-99% of any test set • Ideally, test sets contain in excess of 1000 strains • Strains with MICs above the ECV are considered to have potentially acquired mechanisms of resistance
7
M27-A3 PROPOSED BREAKPOINTS CANDIDA ALBICANS
CURRENTLY PUBLISHED BREAKPOINTS FOR CANDIDA SPP. (µG/ML) 5FC FLU ITRA VORI ANID CAS MICA
S 2
**There are no breakpoints for Cryptococcus spp., Trichosporon spp., Saccharomyces spp., etc.
