NG-test CARBA 5

Summary and principal

β-Lactams are first-line antibiotics for the treatment of infections caused by Enterobacteriaceae. Nevertheless, since the beginning of their massive use in the 1940s, their efficacy has been challenged by the production of enzymes which inactivate them: the β-lactamases. Among them are carbapenemases which hydrolyze carbapenem antibiotics. Before the 1940s, most of the resistance to antibiotics was associated with the production of Extended-Spectrum β-Lactamases (ESBLs) belonging to classes A, B, C, and D of Ambler’s classification. Since then, studies have shown an increase in the production of carbapenemases among the Enterobacteriaceae family. Among those carbapenemases, the β- lactamase KPC (Class A) has spread worldwide in the 2000s. In addition, the metallo β- lactams (MBL) of IMP type, VIM and NDM (Class B) as well as OXA-48 (Class D) have also expanded1,3. These carbapenemases are mainly detected in hospital settings and are responsible for most of the nosocomial infections, raising major global health problems since their presence can be difficult to detect.

NG-Test CARBA 5 is an in vitro rapid and visual multiplex immunochromatographic assay that detects one or more of the five common types of carbapenemase enzymes (KPC (K), OXA-48-like (O), IMP (I), VIM (V), NDM (N)) in bacterial colonies. Liquid extraction buffer is used as a cell lysing solution when mixed with colonies. Monoclonal antibodies that individually recognize each of the five carbapenemases are immobilized on a nitrocellulose membrane. Free monoclonal antibodies are present in the conjugate pad and labelled with colloidal gold. Upon addition of colonies mixed with extraction buffer to the sample pad, the capillary action of the nitrocellulose draws the sample through the mobile antibodies and immobile antibodies on the test strip. The immobilized control antibodies capture any mobile antibodies that run through the sample pad and nitrocellulose without binding to other test lines. A positive result occurs when a red line appears on the control region (C) and one or more lines appear in the test regions (K, O, V, I, or N) and indicates that the sample contains one or more carbapenemases. A negative result occurs when only the control line is observed and indicates that the sample does not contain any of the 5 carbapenemases. If the control line does not appear, the test result is invalid.