Performance of a System for Rapid Phenotypic Antimicrobial Susceptibility Testing of Gram-Negative Bacteria Directly from Positive Blood Culture Bottles
نویسنده : J. Göransson, a M. Sundqvist, b E. Ghaderi, c J. G. Lisby, d Y. Molin, a E. Eriksson, a S. Carlsson, a A. Cederlöf, a L. Ellis, a J. Melina
تاریخ انتشار : 1402/02/11
The evaluated ASTar BC G2 kit uses
a broad panel of 23 antimicrobials for the treatment of BSIs caused by Gram-negative
fastidious and nonfastidious bacteria across a range of 6 to 14 2-fold dilutions, including
cefoxitin as a screening agent for AmpC-producing Enterobacterales. The ASTar
system processes blood culture samples to generate data on MICs and susceptible, intermediate, or resistant (SIR) category. The automated protocol includes concentration
determination and concentration adjustment to enable a controlled inoculum, followed
by broth microdilution (BMD) and microscopy performed continuously to generate MIC
values within approximately 6 h once the test is run on the ASTar system. The performance of the ASTar system was assessed against the ISO 20776-2:2007 standard BMD
reference method. Testing was performed across three sites, with results from 412 contrived blood cultures and 74 fresh clinical blood cultures. The ASTar system was also
tested for reproducibility, with triplicate testing of 11 strains. The accuracy study comprised 8,650 data points of bacterium-antimicrobial tests. The ASTar system demonstrated an overall essential agreement (EA) of 95.8% (8,283/8,650) and a categorical
agreement (CA) of 97.6% (8,433/8,639) compared to the reference BMD method. The
overall rate of major discrepancies (MDs) was 0.9% (62/6,845), and that of very major
discrepancies (VMDs) was 2.4% (30/1,239). This study shows that the ASTar system delivers reproducible results with overall EA and CA of .95%