[Comparative study of Vitek-2™ AIX versus Vitek-2™ PC: phenotypic resistance of enterobacteriaceae to β-lactams].
OBJECTIVE
Vitek-2™ AIX versus Vitek-2™ PC have different rules for phenotypic interpretation. The aim of this study is to ensure that the raw results determined by these two versions of Vitek-2™ allow biologists to conclude to the same resistance phenotype, but also to evaluate their own phenotypic interpretation system (advanced expert system).


METHODS
A total of 251 strains of Enterobacteriaceae of different groups and phenotypes was tested. Each strain was studied simultaneously on both types of Vitek-2™ from the same calibrated inoculum. We then compared their resistance phenotype to beta-lactams.


RESULTS
For strains not producing ESBL or CHN, the biologist concluded in 99.3% of cases to the same resistance phenotype by interpreting the raw results of Vitek-2™ AIX versus PC. The phenotypic interpretation of biologist is different from the Vitek-2™ in respectively 40% versus 43% of cases for AIX and PC versions. For multi-resistant strains, the biologist concluded in 100% of cases to the same resistance phenotype by interpreting the raw results of Vitek-2™ AIX versus PC. In 51.5% of cases the biologist use the disk diffusion method (DD). The results of this technique put forward 29% discrepancy with the two types of Vitek-2™. Finally, when Vitek-2™ claims the presence of an ESBL alone, this result is routinely confirmed by DD.


CONCLUSIONS
The switch from Vitek-2™ AIX to Vitek-2™ PC does not alter the results of the phenotypic interpretation of biologist.
Lefèvre
S
S
Laboratoire de bacte´riologie, hopitaux universitaires de Strasbourg, 67000 Strasbourg, France.
Cocquerelle
V
V
Riegel
P
P
Scheftel
J-M
JM
Jaulhac
B
B
Jehl
F
F
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D057205:Automation, Laboratory / Q000295:instrumentation; D001330:Electronic Data Processing / Q000592:standards; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000382:microbiology*; D057166:High-Throughput Screening Assays / Q000295:instrumentation / Q000379:methods; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D010641:Phenotype; D018440:beta-Lactam Resistance / Q000502:physiology*; D001618:beta-Lactamases / Q000378:metabolism; D047090:beta-Lactams / Q000627:therapeutic use
D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases