Evaluation of an immunological assay for the identification of multiple carbapenemase-producing Gram-negative bacteria

Carbapenemase-producing Gram-negative organisms (CPOs) frequently gain multidrug-resistant phenotypes and thereby limit the therapeutic options available. Colonisation and infection with CPOs are critical risks for mortality in clinical settings, especially in critical care medicine. Carbapenemase genes on plasmids have transferred to many Gram-negative species, and these species have spread, leading to global concern regarding antimicrobial resistance. A molecular rapid diagnostic test (mRDT) for CPOs is urgently required in critical care medicine. Here, we evaluated a rapid lateral flow immunoassay (LFIA) for CPOs isolated from patients at university hospitals, including intensive care units, and compared the results with those obtained using the multiplex polymerase chain reaction (PCR) method. NG-test CARBA 5 detected multiple carbapenemases, KPC, OXA-48, NDM, VIM, and IMP variants expressed in clinical isolates. Quick Chaser IMP detected IMP variants. The LFIAs exhibited 100% sensitivity and specificity relative to clinical isolates on agar plates. By contrast, the multiplex PCR method exhibited a limited ability to detect IMP-7-producing isolates not belonging to the IMP1 group, which resulted in 97% sensitivity and 100% specificity for IMP-producing isolates. Our results demonstrate that the LFIA is a useful mRDT to identify CPOs and has an advantage over the PCR method for both detection time and sensitivity to the IMP groups. LFIA could complement the nucleic acid amplification test used to identify CPOs. In conclusion, we evaluated sensitive and specific LFIAs capable of detecting carbapenem-ase production in Gram-negative bacteria. We anticipate that LFIAs will become a point-of-care test enabling rapid detection of carbapenemases in hospital settings, particularly in intensive care units.