Validation of Rapid Antimicrobial Susceptibility Testing directly from blood cultures using WASPLab ®, including Colibrí™ and Radian® in-Line Carousel

AbstractWith the increase in antimicrobial resistance, fast reporting of antimicrobial susceptibility testing (AST) results is becoming increasingly important. EUCAST developed a method for rapid AST (RAST) directly from the broth of positive blood cultures (BC). Inhibition zones are read after 4, 6, and 8  h, with specific breakpoints per time point. We evaluated the RAST method based on EUCAST disk diffusion methodology with inoculation of BC broth using WASPLab® (inclusive Colibr í™ and Radian®). Forty-nine non-duplicate strains were tested:Escherichia coli n = 17,Klebsiella pneumoniae n = 7,Pseudomonas aeruginosa n = 4,Acinetobacter baumannii n = 2,Staphylococcus aureus n = 10,Enterococcus faecalis n = 6, andEnterococcus faecium n = 3. Results were compared to direct AST and standardized AST. Good categorical agreement was obtained at all time points for all groups, exceptP. aeruginosa. RAST cut-offs for extended-spectrum β-lactamase (ESBL)-producingEnterobacterales enabled the detection of all included ESBL isolates (n = 5) at all time points, except for 1E. coli ESBL after 4  h. RAST cut-offs for carbapenemase-producingEnterobacterales enabled the detection of only one carbapenemase after 6  h. However, all carbapenemases (n = 3) were correctly detected after 8 h. Two methicillin-resistantS. aureus were included; both were correctly categorized as cefoxitin-resistant at 6 and 8  h. At 4 h, there was insufficient growth for...
Source: European Journal of Clinical Microbiology and Infectious Diseases - Category: Microbiology Source Type: research