Background: A bacteremia diagnosis with speeded-up identification and antimicrobial susceptibility testing (AST) is\nmandatory to adjust empirical broad-spectrum antibiotherapy and avoid the emergence of multi-resistant bacteria.\nAlfred 60AST (Alifax, Polverara, PD, Italy) is an innovative automated system based on light scattering measurements\nallowing direct AST from positive blood cultures with rapid results. In this study we aimed to evaluate the systemâ??s\nperformances and turnaround time (TAT) compared to routine AST.\nMethods: The study was conducted during 2 non-consecutive 3-month periods at the microbiology laboratory of\nthe Cliniques universitaires Saint-Luc. All blood cultures detected positive in the 0 AM-10 AM time frame with a\npure Gram-positive cocci or Gram-negative bacilli stain were included for Alfred 60AST testing. Two customized\nEUCAST antibiotic panels were set up composed of 1) a â??Gram-negativeâ? panel including cefuroxime, ceftazidime\nEnterobacteriaceae, piperacillin-tazobactam Enterobacteriaceae, ciprofloxacine, and ceftazidime Pseudomonas 2) a\nâ??Gram-positiveâ? panel including cefoxitin Staphylococcus aureus, cefoxitin coagulase-negative (CNS) Staphylococci\nand ampicillin Enterococci. Categorical agreement (CA), very major errors (VME), major errors (ME), minor errors (mE)\nand TAT to Alfred 60AST results were calculated in comparison with AST results obtained from direct testing on\npositive blood cultures with the Phoenix system (Becton Dickinson, Franklin Lakes, NJ, USA).\nResults: Five hundred seventy and one hundred nine antibiotics were evaluated on respectively 166 Gram-negative\nbacilli and 109 Gram-positive cocci included in the studied population. During the first study period regarding\nGram-negative strains a CA of 89.5% was obtained with a high rate of VME (19 and 15.4% respectively) for\ncefuroxime and piperacillin-tazobactam Enterobacteriaceae. Considering this, Alifax reviewed these antibioticsâ??\nformulations improving Gram-negative bacilli total CA to 92.2% with no VME during the second study period. For\nGram-positive cocci, total CA was 88.1% with 2.3% VME, 13.8% ME (mainly cefoxitin CNS) and 12% mE rates both\nstudy periods combined. Median TAT to AST results was 5 h with Alfred versus 12 h34 with Phoenix.
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