Evaluation of the Etest for rapid susceptibility testing of Mycobacteriumavium to clarithromycin

MICs of clarithromycin were determined by the Etest method for thirty clinical strains of Mycobacterium avium complex (MAC) and compared with MICs results as determined by the reference agar dilution method. Agreement (within ±1 log 2 dilution) between the Etest and the reference method was 70% for susceptible strains and 100% for resistant strains. No major errors resulting in misclassification in susceptibility or resistance categories were detected for the Etest MIC method. It is suggested that the Etest is easy to perform and is an accurate method for determining susceptibility of MAC strains to clarithromycin.