Evaluation of NG-Test Carba 5 for Rapid Phenotypic Detection and Differentiation of Five Common Carbapenemase Families: Results of a Multicenter Clinical Evaluation

Abstract

Background: NG-Test CARBA 5 is a rapid in vitro multiplex immunoassay for the phenotypic detection and differentiation of five common carbapenemase families (KPC, OXA-48-like, VIM, IMP, and NDM) directly from bacterial colonies. The assay is simple to perform and has recently received United States Food and Drug Administration clearance. Methods: A method comparison study was performed at geographically diverse medical centers (n = 3) in the United States where 309 clinical Enterobacterales and Pseudomonas aeruginosa isolates were evaluated against NG-Test CARBA 5 (NG Biotech, Guipry, France), Xpert Carba-R (Cepheid, Inc., Sunnyvale, CA), mCIM and eCIM, and disk diffusion with carbapenems. Colonies from tryptic soy agar with 5% sheep blood (blood agar) and MacConkey agar were tested and compared to a composite reference method. Additionally, a fourth medical center performed a media comparison study by evaluating NG-Test CARBA 5 performance from blood, MacConkey, and Mueller Hinton agars with 110 clinical isolates of Enterobacterales and P. aeruginosa. These results were compared to the expected genotypic and mCIM results. Results: For the multicenter method comparison study, the positive percent agreement (PPA) and the negative percent agreement (NPA) for the NG-Test CARBA 5 compared to the composite reference method was 100% for both blood and MacConkey agars. The media comparison study at the fourth site showed that the PPA ranged from 98.9-100% and the NPA ranged from 95.5-100% for blood, MacConkey and Mueller Hinton agars. Conclusions: NG-Test CARBA 5 accurately detected and differentiated five common carbapenemase families from Enterobacterales and P. aeruginosa colonies on commonly used agar media. The results of this test will support a streamlined laboratory workflow and will expedite therapeutic and infection control decisions.