Impact of the introduction of EUCAST ’s concept of “area of technical uncertainty”

AbstractOn the first of January 2019, the European Committee on Antimicrobial Susceptibility Testing, EUCAST, introduced the concept of “area of technical uncertainty” (ATU). The aim was to report on the incidence of ATU test results in a selection of common bacterial species and the subsequent impact on antimicrobial resistance categorization and workload. A retrospective analysis of clinical samples collected from February 201 9 until November 2019 was performed. Susceptibility to amoxicillin-clavulanic acid and piperacillin-tazobactam inEnterobacterales (Escherichia spp.,Klebsiella spp.,Proteus spp.), piperacillin-tazobactam inPseudomonas aeruginosa, and amoxicillin-clavulanic acid and cefuroxime inHaemophilus influenzae was studied. Disk diffusion antibiotic susceptibility testing was read and interpreted by ADAGIO 93400 automated system (Bio-Rad, France). In case of an inhibition zone in the ATU, strains were retested using gradient minimal inhibitory concentration method (Etest, BioM érieux, France). Overall, 14,164 isolate-antibiotic combinations were tested in 7922 isolates, resulting in 1204 (8.5%) disk zone diameters in the ATU region. Retesting of ATUs with Etest resulted in a category change from S to R for amoxicillin-clavulanic acid in 63/498 (12.7%) ofEscherichia spp., 2/58 (3.4%) ofKlebsiella spp., 2/37 (5.4%) ofProteus spp., and 6/125 (4.8%) ofHaemophilus influenzae. For piperacillin-tazobactam, a category change from S to R was found in 33/92 (35.9%) of...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research