Objectives: The aim of this study was to compare the performance of the NG-Test CARBA-5 with the GeneXpert CARBA-R for confirming carbapenemases in Enterobacterales isolated from CPE screens and clinical specimens to improvecarbapenemase detection and turnover times to prevent spread of antimicrobial resistance.
Method: 57 different enterobacterales (1 GES, 1 AIM, 8 KPC, 13 OXA, 8 VIM, 14 IMP and 14 NDM) consisting of 55 carbapenemase producers and 2 non carbapenemase producers were tested with the CARBA-5, CARBA-R, and the Bio-rad β-carba tests. All isolates were speciated using Bruker MALDI-Tof. Samples which provided mismatched results with the CARBA-5 and CARBA-R were sent for whole genome sequencing to detect which carbapenemase variant was detected and see if one test was more sensitive.
Results: All 6 negative sample controls passed on both tests. Both tests detected 100% of the KPC, VIM, OXA-48-like and NDM carbapenemases. Both tests did not detect the OXA-23 as expected. The CARBA-R only detected 64% of IMP carbapenemases (9/14) while the CARBA-5 correctly identified 93% of IMP genes(13/14).
Conclusions: While both tests exhibited high sensitivity for the detection of 4 of the 5 tested carbapenemases, the CARBA-5 was able to detect IMP at a higher percentage (29% increase) than the CARBA-R. The CARBA-5 is a more rapid, simple, and sensitive way of testing for carbapenemases than the CARBA-R and can be used in place of the CARBA-R in laboratories.