Evaluation of the Carbapenemase Detection Kit (Colloidal Gold; Macro & Micro Test): a new immunochromatographic assay for rapid detection of carbapenemases in Enterobacterales

Rapid identification of carbapenemase-producing Enterobacterales (CPE) is crucial to ensure timely implementation of infection control measures and to guide administration of active antimicrobials. Over the past decade, the frequency of CPE has increased worldwide.1 The main carbapenemases now involved are Class A enzymes (KPC), Class B metallo-β-lactamases (notably NDM, VIM, and IMP) and Class D oxacillinases (especially OXA-48-like). Lateral-flow immunochromatographic assays are widely used for carbapenemase detection because they are rapid, inexpensive, and easy to implement, and several are already routinely used in clinical microbiology laboratories.2 In this study, we evaluated the performance of a newly commercialized assay, the Carbapenemase Detection Kit (Colloidal Gold; Macro & Micro Test) (M&M Carba Test), using a large and diverse collection of Enterobacterales isolates. To evaluate the performance of the M&M Carba Test, we used a well-characterized Enterobacterales collection previously studied in our laboratory.3 To better reflect the current epidemiology and include recently emerging variants, this cohort was supplemented with additional carbapenemase-producing isolates. In total, 242 isolates were tested, including 194 carbapenemase producers: 188 producing carbapenemases targeted by the assays and six producing non-targeted enzymes (IMI, SME, GES, FRI, or non–OXA-48-like oxacillinases), as well as 48 non-carbapenemase producers, collected from different regions across France (Table S1, available as Supplementary data at JAC Online). All isolates were characterized by WGS using Illumina technology as previously described.4