Evaluation of the Revogene Carba C Assay for Detection and Differentiation of Carbapenemase-Producing Gram-Negative Bacteria.

The Revogene Carba C assay (formerly GenePOC Carba assay) is a multiplex nucleic acid-based in vitro diagnostic test intended for the detection of carbapenemase-producing Enterobacterales (CPE) from cultured colonies. This assay was evaluated directly on colonies of 118 well-characterized Enterobacterales with reduced susceptibility to carbapenems and on 49 multidrug-resistant (MDR) Pseudomonas aeruginosa and 40 MDR Acinetobacter baumannii isolates. The Revogene Carba C assay's performance was high, as it was able to detect the five major carbapenemases (NDM, VIM, IMP, KPC, and OXA-48). In Enterobacterales, sensitivity and specificity were 100%. When extrapolating the results to the French CPE epidemiology between 2012 and 2018, this assay would have detected 99.28% of the 9,624 CPE isolates sent to the French NRC, missing 69 CPE isolates (2 GES-5, 10 OXA-23, 2 TMB-1, 1 SME-4, 53 IMI, and 1 FRI). The overall sensitivity and specificity for CP P. aeruginosa were 93.7 and 100%, respectively, as two rare IMP variants (IMP-31 and -46) were not detected. Extrapolating these results to the French epidemiology of CP P. aeruginosa in 2017, 93.3% would have been identified, missing only 1 DIM and 10 GES variants. The Revogene Carba C assay accurately identified the targeted carbapenemase genes in A. baumannii, but when extrapolating these results to the French CP A. baumannii epidemiology of 2017, only 12.50% of them could be detected, as OXA-23 is the most prevalent carbapenemase in CP A. baumannii The Revogene Carba C assay showed excellent sensitivity and specificity for the five most common carbapenemases regardless of the bacterial host. It is well adapted to the CPE and CP P. aeruginosa epidemiology of many countries worldwide, which makes it suitable for use in the routine microbiology laboratory, with a time to result of ca. 85 min for eight isolates simultaneously.

Improvement of the Immunochromatographic NG-Test Carba 5 Assay for the Detection of IMP Variants Previously Undetected.

Here, we evaluated the immunochromatographic assay NG-Test Carba 5v2 (NG-Biotech), with improved IMP variant detection on 31 IMP producers, representing the different branches of the IMP phylogeny, including 32 OXA-48, 19 KPC, 12 VIM, 14 NDM, and 13 multiple carbapenemase producers (CPs), 13 CPs that were not targeted, and 13 carbapenemase-negative isolates. All tested IMP variants were accurately detected without impairing detection of the other carbapenemases. Thus, NG-Test Carba 5v2 is now well adapted to countries with high IMP prevalence and to the epidemiology of CP-Pseudomonas aeruginosa, where IMPs are most frequently detected.