The current role of the reference procedures by CLSI and EUCAST in the detection of resistance to antifungal agents in vitro

Abstract

The role of antifungal susceptibility testing (AFST) reference procedures seems to be restricted to a number of uses and to being performed in reference laboratories, since several automated or semi-automated commercial systems and methods based on the disk diffusion technique were developed. These methods have been shown to have a high correlation with reference procedures and provide simple, flexible and affordable alternative susceptibility testing procedures for use in the clinical laboratory. One of the most important current tasks of the reference procedures is establishing antifungal breakpoints to interpret the AFST results. The procedure by the Clinical Laboratory Standards Institute to develop MIC interpretative breakpoints is based on the analysis of the MIC distribution and the clinical relationship between MIC values and efficacy. The emergence of resistance to licensed antifungal agents and the description of therapeutic failures related to high MIC values underscore the need for continued surveillance. The surveillance should be carried out using the reference procedures and taking into account the breakpoints established by the expert committees of the Clinical Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing. In addition, reference procedures of AFST provide a standard basis from which new AFST methods and techniques can be developed and compared. The evaluation of new antifungal agents and the susceptibility profile of rare and emerging species should also be performed by the reference techniques. Modifications of the reference procedures can even be used to test fastidious microorganisms for which routine techniques are not useful.

Keywords::

• antifungal breakpoint
• antifungal epidemiological cut-off
• CLSI
• EUCAST

Financial & competing interests disclosure

In the past 5 years, Manuel Cuenca-Estrella has received grant support from Astellas Pharma, bioMerieux, Gilead Sciences, Merck Sharp and Dohme, Pfizer, Schering Plough, Soria Melguizo SA, the EU, the ALBAN program, the Spanish Agency for International Cooperation, the Spanish Ministry of Culture and Education, The Spanish Health Research Fund, The Instituto de Salud Carlos III, The Ramon Areces Foundation and The Mutua Madrileña Foundation. He has been an advisor/consultant to the PAHO, Gilead Sciences, Merck Sharp and Dohme, Pfizer and Schering Plough. He has been paid for talks on behalf of Gilead Sciences, Merck Sharp and Dohme, Pfizer, Astellas Pharma and Schering Plough. In the past 5 years, Juan Luis Rodriguez-Tudela has received grant support from Astellas Pharma, Gilead Sciences, Merck Sharp and Dohme, Pfizer, Schering Plough, Soria Melguizo SA, the EU, the Spanish Agency for International Cooperation, the Spanish Ministry of Culture and Education and The Spanish Health Research Fund, The Instituto de Salud Carlos III, The Ramon Areces Foundation and The Mutua Madrileña Foundation. He has been an advisor/consultant to the PAHO, Gilead Sciences, Merck Sharp and Dohme, Mycognostica, Pfizer and Schering Plough. He has been paid for talks on behalf of Gilead Sciences, Merck Sharp and Dohme, Pfizer and Schering Plough. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.