Evaluation of EUCAST rapid antimicrobial susceptibility testing (RAST) for positive blood cultures in clinical practice using a total lab automation

AbstractOur objective was to evaluate EUCAST ’s ‘rapid antimicrobial susceptibility testing’ (RAST) directly from positive blood culture that delivers antimicrobial results within 6 h forStaphylococcus aureus,Enterococcus spp.,Escherichia coli,Klebsiella pneumoniae andPseudomonas aeruginosa, using total lab automation. Zone diameters from RAST were compared with MIC results. Furthermore, its influence on time to report was investigated. RAST was performed to all positive aerobic and anaerobic blood culture bottles by subculturing them, i.e. onto Mueller-Hinton agar and adding six antibiotic discs covering Gram-negative and Gram-positive therapy (cefoxitin, ampicillin, vancomycin, piperacillin/tazobactam, meropenem and ciprofloxacin). RAST was automatically imaged after 6  h. Zone sizes were measured using a TLA software tool and interpreted according to EUCAST clinical breakpoints. Bacteria were identified using MALDI-TOF MS and MIC results were determined using Vitek2 panels. Categorial agreement between agar diffusion and MIC results was investigated. Additionall y, time to RAST and time to Vitek were compared for 100 isolates (20 per species). Between November 2018 and April 2019, 3313 positive mono-bacterial blood culture bottles were collected of which 894 bottles with RAST-validated species were investigated. Among these bottles, 2029 individual antibiot ic measurements were compared with MIC results from Vitek2 and 14 very major, 28 major and 12 minor errors we...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research