Performance evaluation of the Becton Dickinson Kiestra™ IdentifA/SusceptA.

Abstract Objectives New automated modules are required to provide fully automated solutions in diagnostic microbiology laboratories. We evaluated the performance of a Becton Dickinson Kiestra™ IdentifA/SusceptA prototype for MALDI-TOF identification (ID) and PhoenixTM antibiotic susceptibility testing (AST). Methods The performance of the IdentifA/SusceptA coupled prototype was compared to manual processing for MALDI-TOF ID on 1302 clinical microbial isolates or ATCC strains and for PhoenixTM M50 AST on 484 strains, representing 61 species. Results Overall, the IdentifA exhibited similar ID performances than manual spotting. Higher performances were observed for Gram-negative bacteria with an ID at the species level (score>2) of 96.5% (369/382) and 86.9% (334/384), respectively. A significant better performance was observed with the IdentifA (95.2%, 81/85) compared to manual spotting (75.2%, 64/85) from colonies on MacConkey agar. Contrariwise, the IdentifA exhibited lower ID performances at the species level than manual processing for streptococci (76.1%, 96/126 compared to 92%, 115/125), coagulase-negative staphylococci (73.3%, 44/60 compared to 90%, 54/60) and yeasts (41.3%, 19/46 compared to 78.2%, 36/46). Staphylococcus aureus and enterococci were similarly identified by the two approaches, with ID rates of 92% (65/70) for the IdentifA and 92.7%, (64/69) for manual processing and 94.8%, (55/58) for the IdentifA and 98.2%, (57/58) for manual processing, respectively. The SusceptA exhibited an AST overall essential agreement of 98.82% (6863/6945), a category agreement of 98.86% (6866/6945), 1.05% (6/570) very major errors, 0.16% (10/6290) major errors, and 0.91% (63/6945) minor errors compared to the reference AST. Conclusions Overall, the automated IdentifA/SusceptA exhibited high ID and AST performances.