Performance of Vitek 2 for antimicrobial susceptibility testing of Enterobacteriaceae with Vitek 2 (2009 FDA) and 2014 CLSI breakpoints.

Vitek 2 (bioMérieux Inc., Durham, NC) is a widely used commercial antimicrobial susceptibility test system. We compared the MIC results obtained using the Vitek 2 AST-GN69 and AST-XN06 cards to those obtained by CLSI broth microdilution (BMD) for 255 isolates of Enterobacteriaceae, including 25 isolates of carbapenem-resistant Enterobacteriaceae. In total, 25 antimicrobial agents were examined. For 10 agents, the MIC data were evaluated using two sets of breakpoints: (i) the Vitek 2 breakpoints, which utilized the 2009 FDA breakpoints at the time of the study and are equivalent to the 2009 CLSI M100-S19 breakpoints, and (ii) the 2014 CLSI M100-S24 breakpoints. There was an overall 98.7% essential agreement (EA). The categorical agreement was 95.5% (CA) using the Vitek 2 breakpoints and 95.7% using the CLSI breakpoints. There was 1 very major error (VME) (0.05%) observed using the Vitek 2 breakpoints (cefazolin) and 8 VMEs (0.5%) using the CLSI breakpoints (2 each for aztreonam, cefepime, and ceftriaxone, and 1 for cefazolin and ceftazidime). Fifteen major errors (MEs) (0.4%) were noted using the Vitek 2 breakpoints and 8 (0.5%) using the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD for testing a limited number of Enterobacteriaceae commonly isolated by clinical laboratories. Ongoing studies are warranted to assess performance in isolates with emerging resistance.

Bobenchik AM ，Deak E ，Hindler JA ，Charlton CL ，Humphries RM ... -  《-》

Performance of Vitek 2 for Antimicrobial Susceptibility Testing of Acinetobacter baumannii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia with Vitek 2 (2009 FDA) and CLSI M100S 26th Edition Breakpoints.

The performances of Vitek 2 AST-GN69 and AST-XN06 cards were compared to Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) for 99 isolates of Pseudomonas aeruginosa, 26 Acinetobacter baumannii isolates, and 11 Stenotrophomonas maltophilia isolates. In total, 15 antimicrobials were evaluated, with 11 for P. aeruginosa, 14 for A. baumannii, and 2 for S. maltophilia Categorical agreement (CA) was assessed using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. The essential agreement values for P. aeruginosa, A. baumannii, and S. maltophilia were 99.5%, 99.2%, and 100%, respectively. The CA values for P. aeruginosa, A. baumannii, and S. maltophilia were 94.1%, 92.7%, and 95.5%, respectively, by the Vitek 2 breakpoints, and 93.4%, 92.3%, and 95.5%, respectively, by the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. Improved performance was noted for the reformulated piperacillin-tazobactam and imipenem found on the AST-GN69 card, with no very major or major errors noted when using the CLSI breakpoints.

Bobenchik AM ，Deak E ，Hindler JA ，Charlton CL ，Humphries RM ... -  《-》

Comparison of disk diffusion, VITEK 2, and broth microdilution antimicrobial susceptibility test results for unusual species of Enterobacteriaceae.

Stone ND ，O'Hara CM ，Williams PP ，McGowan JE Jr ，Tenover FC ... -  《-》

Cephalothin is not a reliable surrogate marker for oral cephalosporins in susceptibility testing of Enterobacteriaceae causing urinary tract infection.

Vitek® 2 (bioMérieux) is a widely used commercial antimicrobial susceptibility test (AST) system. AST-N244 card includes cephalothin as first-generation cephalosporin. We compared the cephalothin susceptibility results obtained with Vitek® 2 AST-N244 to those obtained by broth microdilution (BMD) and disk diffusion (DD) for 212 urinary Enterobacteriaceae. We also evaluated the differences between cefazolin and cephalothin susceptibility results. The overall performance of Vitek® 2 for cephalothin testing was 74.5% and 76.4% category agreement compared to BMD and DD, respectively; 84.4% essential agreement; very major errors 15.2% and 11.1% compared to BMD and DD; major errors 0% compared to both methods; and minor errors 22.2% and 21.7% compared to BMD and DD. Regarding correlation between cephalothin and cefazolin, the differences observed were statistically significant (P<0.0001) for the 167 Escherichia coli included (39.5% cephalothin susceptible versus 92.2% cefazolin susceptible by BMD; 41.9% cephalothin susceptible versus 93.4% cefazolin susceptible by DD). Vitek® 2 should provide cefazolin instead of cephalothin as a surrogate marker for oral cephalosporins on the urinary AST-244 cards in order to follow the CLSI (2016) recommendations.

López IA ，Montes JC ，Álvarez MJ ，Mazarrasa CF ，Martínez-Martínez L ... -  《-》

Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and CLSI screening parameters for the detection of extended-spectrum β-lactamase production in clinical Enterobacteriaceae isolates.

Polsfuss S ，Bloemberg GV ，Giger J ，Meyer V ，Hombach M ... -  《-》