Vérification des performances d'une méthode : l'étude de la sensibilité aux antibiotiques par la technique des E-test®

Antimicrobial susceptibility testing by E-test® is based on strips coated with an exponential gradient of antibiotic. The E-test® method is a qualitative test method with an interpretation in therapeutic categories (sensitive, intermediate, resistant). The E-test® susceptibility testing method is based on the diffusion of the antibiotic from a preformed antibiotic gradient from a strip. The aim of this work is to contribute to meet the requirements of the standard ISO 15189 in terms of performances' check, harmonization of the professional practises and evaluation of the skills/know-how. The study was realized by measuring 90 minimal inhibitory concentrations with 17 types of different E-test® strips (15 bactericidal and 2 bacteriostatic antibiotics), 7 ATCC' strains, 5 samples of external quality controls and 25 clinical isolates. The implementation of the tests is delicate on the one hand because of the supplier's recommandations which must be necessarily respected and on the other hand the difficulties of reading and interpretation of the tests.