Objectives: To compare the performance of the Accelerate Pheno™ system with that of the conventional phenotypic VITEK® 2 system for rapid antimicrobial susceptibility testing (AST) of bacterial pathogens from positive blood culture (PBC) samples, based on the reference broth microdilution (BMD) method. Methods: Prospectively collected PBCs that represented patient-unique bloodstream infection episodes were included. For PBC samples showing monomicrobial growth (n = 86), AST was performed using both Accelerate Pheno™ and VITEK® 2 systems directly from PBC broth. Colony isolates derived from subculture of PBC broth were then used for BMD testing. AST results were interpreted according to 2017 EUCAST breakpoints. Results: The overall categorical agreement between Accelerate Pheno™ system and BMD was 92.7% (467/504) for Gram-negative organisms and 99.0% (95/96) for Gram-positive organisms, with rates for very major errors of 3.6% (6/166), major errors 2.2% (9/416) and minor errors 3.8% (23/600). The overall categorical agreement between the VITEK® 2 system and BMD was 91.7% (463/505) for Gram-negative organisms and 99.0% (97/98) for Gram-positive organisms, with rates of very major errors of 2.4% (4/169), major errors 1.0% (4/416) and minor errors 5.8% (35/603). Importantly, unlike the VITEK® 2 system, no false-susceptible results occurred with two colistin-resistant organism-growing PBCs tested using the Accelerate Pheno™ system. Conclusions: Based on these findings, the Accelerate Pheno™ system can be a valid alternative for the rapid AST of Gram-negative and Gram-positive bacteria in bloodstream infections.

De Angelis, G., Posteraro, B., Menchinelli, G., Liotti, F. M., Spanu, T., Sanguinetti, M., Antimicrobial susceptibility testing of pathogens isolated from blood culture: a performance comparison of Accelerate Pheno (TM) and VITEK (R) 2 systems with the broth microdilution method, <<JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY>>, 2019; 74 (1): 24-31. [doi:10.1093/jac/dky532] [http://hdl.handle.net/10807/129553]

Antimicrobial susceptibility testing of pathogens isolated from blood culture: a performance comparison of Accelerate Pheno (TM) and VITEK (R) 2 systems with the broth microdilution method

De Angelis, Giulia;Posteraro, Brunella;Menchinelli, Giulia;Liotti, Flora Marzia;Spanu, Teresa;Sanguinetti, Maurizio
2019

Abstract

Objectives: To compare the performance of the Accelerate Pheno™ system with that of the conventional phenotypic VITEK® 2 system for rapid antimicrobial susceptibility testing (AST) of bacterial pathogens from positive blood culture (PBC) samples, based on the reference broth microdilution (BMD) method. Methods: Prospectively collected PBCs that represented patient-unique bloodstream infection episodes were included. For PBC samples showing monomicrobial growth (n = 86), AST was performed using both Accelerate Pheno™ and VITEK® 2 systems directly from PBC broth. Colony isolates derived from subculture of PBC broth were then used for BMD testing. AST results were interpreted according to 2017 EUCAST breakpoints. Results: The overall categorical agreement between Accelerate Pheno™ system and BMD was 92.7% (467/504) for Gram-negative organisms and 99.0% (95/96) for Gram-positive organisms, with rates for very major errors of 3.6% (6/166), major errors 2.2% (9/416) and minor errors 3.8% (23/600). The overall categorical agreement between the VITEK® 2 system and BMD was 91.7% (463/505) for Gram-negative organisms and 99.0% (97/98) for Gram-positive organisms, with rates of very major errors of 2.4% (4/169), major errors 1.0% (4/416) and minor errors 5.8% (35/603). Importantly, unlike the VITEK® 2 system, no false-susceptible results occurred with two colistin-resistant organism-growing PBCs tested using the Accelerate Pheno™ system. Conclusions: Based on these findings, the Accelerate Pheno™ system can be a valid alternative for the rapid AST of Gram-negative and Gram-positive bacteria in bloodstream infections.
2019
Inglese
De Angelis, G., Posteraro, B., Menchinelli, G., Liotti, F. M., Spanu, T., Sanguinetti, M., Antimicrobial susceptibility testing of pathogens isolated from blood culture: a performance comparison of Accelerate Pheno (TM) and VITEK (R) 2 systems with the broth microdilution method, <<JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY>>, 2019; 74 (1): 24-31. [doi:10.1093/jac/dky532] [http://hdl.handle.net/10807/129553]
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