Development of an immunochromatographic assay for diagnosing the production of IMP-type metallo-β-lactamases that mediate carbapenem resistance in Pseudomonas

Rapid and reliable detection of carbapenem-resistant bacteria is an important infection-control measure and a crucial aspect of antimicrobial chemotherapy. IMP-type metallo-beta-lactamase (MBL) is an emzyme that mediate carbapenem resistance in bacteria. Here, an immunochromatographic assay was newly developed using novel monoclonal antibodies (mAbs) recognizing IMP-type MBL. Epitope mapping of mAbs and mutational analysis of the epitope region in IMP antigen suggested that the mAbs could react to all known subtypes of IMP-type MBL Evaluation of the assay using Pseudomonas aeruginosa strains (n = 248) showed that the results of the immunochromatographic detection of the IMP-type MBLs were fully consistent with those of the PCR analysis for bla(IMP) genes, showing false positives and negatives. All positive strains were resistant to carbapenem (MIC >= mu g/ml). The assay also accurately distinguished the production of IMP-type MBLs in Pseudomonas putida, Acinetobacter baumannii, and Alcaligenes xylosoxidans. The detection limit of the assay was 5.7 x 10(4) cfu per test. Taken together, these data suggest that the developed assay can be used for rapid and reliable diagnosis of the production of IMP-type MBLs in Gram-negative bacteria. (C) 2011 Elsevier B.V. All rights reserved.