Analytical Evaluation of KarbaDia, a Multiplex Immunochromatographic Assay for Rapid Detection of Major Carbapenemase Families in Gram-Negative Bacteria

Background: Rapid detection of carbapenemase-producing Gram-negative bacteria is critical for timely antimicrobial stewardship and infection control interventions. This study evaluated the analytical diagnostic performance of KarbaDia as a new multiplex lateral flow
immunochromatographic assay for rapid detection of KPC, NDM, VIM, IMP, and OXA-48-like carbapenemases.
Materials & Methods: An analytical diagnostic accuracy evaluation study was conducted using 78 non-duplicate well-characterized Gram-negative bacterial isolates obtained from publicly available diversity panels. The collection included carbapenemase-producing and carbapenemase-negative isolates of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Whole genome sequencing (WGS) served as the reference standard. KarbaDia (GaDia SA, Switzerland) was evaluated in parallel with the Carbapenemase Detection Kit (Colloidal Gold; Macro & Micro-Test). Sensitivity, specificity, and 95% confidence intervals
(CI) were calculated for each carbapenemase family and for overall assay performance.
Findings: KarbaDia demonstrated 100% sensitivity for KPC (6 of 6), NDM (13 of 13), VIM (3 of 3), and IMP (2 of 2) and 90.0% for OXA-48-like enzymes (9 of 10). The overall sensitivity was 97.1% (95% CI: 85.1–99.9), while the specificity reached 100% (95% CI: 99.0–100). No false-positive results were observed. The comparator assay demonstrated similar overall sensitivity (97%) but produced four invalid results (4.8%), mainly associated with viscous K. pneumoniae colonies and incomplete chromatographic migration.
Conclusion: KarbaDia demonstrated high analytical accuracy for rapid and multiplex detection of major carbapenemase families. The assay combines rapid turnaround time, multiplex capability, and ease of visual interpretation without dedicated instrumentation.
These characteristics support its potential applicability in routine clinical microbiology laboratories; however, prospective multicenter clinical validation studies remain necessary before routine implementation.