Evaluation of a laboratory rapid test for confirmation and characterisation of carbapenemase-producing bacteria in MSF laboratories
Study design
Retrospective laboratory test evaluation
Context
Carbapenemase-producing Gram-negative bacilli (CP-GNB) have emerged as a major global health concern. Confirmation and characterisation of CP-GNB are crucial for infection prevention and control (IPC) and antimicrobial stewardship (AMS). However, MSF laboratories rely solely on phenotypic detection of carbapenem resistance. This study evaluated the accuracy and ease-of-use of the rapid laboratory test Carba 5 (NG-Biotech) in confirming and detecting the five most common carbapenemases (NDM, VIM, KPC, IMP, OXA-48 like) in CP-GNB isolated in MSF laboratories.
Our role
Coordination
Partenaire
- Ministry of health
- American University of Beirut
Methods
The retrospective evaluation included carbapenem-resistant Enterobacterales (CRE, n=252) and Pseudomonas aeruginosa (CRPA, n=32) isolated from blood and bone cultures collected in MSF-supported hospitals in DRC, Niger and Jordan between 2019 and 2024. Results were compared to a composite reference method: (i) carbapenem inactivation method (CIM); and (ii) whole genome sequencing (WGS) performed at the American University of Beirut (analyses still ongoing). Trained laboratory technicians performed the Carba-5 test and CIM in the MSF laboratories. We evaluated the usability of the Carba-5 test and CIM through self-administered questionnaires completed post-training and at the end of the study.
Preliminary results
Among CRE, Carba-5 test showed a 98% (152/155) positive and 98% (92/95) negative agreement with CIM. According to partial WGS results, NDM is the main carbapenemase produced by the CP-Enterobacterales in DRC (20/20) and Niger (49/49). In Jordan, we observed NDM (52/54), VIM (1/54) and KPC (1/54). Among CRPA, Carba-5 test showed a 100% (11/11) positive and 100% (18/18) negative agreement with CIM and WGS. According to partial WGS results, NDM and OXA are the most frequent carbapenamases in DRC and Jordan. The Carba-5 test was reported as easy to use and interpret, while CIM was timeconsuming and challenging to perform and interpret.
Conclusion
This study contributes to the knowledge of CP-GNB epidemiology in 3 MSF projects. Preliminary results showed Carba-5 test as an acceptable and easy-touse diagnostic tool. However, additional confirmatory results are needed to estimate accuracy for carbapenemase typing, and define the optimal diagnostic algorithm for screening and confirmation of CP-GNB.
