Evaluation of the rapid lateral flow assay (LFA) for detection of five major carbapenemase enzyme families in genotypically characterised bacterial isolates

Background & objectives Antimicrobial resistance has steadily become a grave public health problem worldwide, making carbapenems, often the last choice of antibiotic, for treating infections involving multidrug-resistant Gram-negative organisms. The production of carbapenemases is one of the primary mechanisms responsible for the development of resistance. KPC, NDM, VIM, IMP, and OXA-48-like are the most prevalent carbapenemases. Identification of CROs is based on the resistance phenotype or requires molecular assays, which are not widely available. A lateral flow assay (LFA) has been developed to enable rapid identification of carbapenemase production in cultured bacteria. Methods A total of 87 isolates characterised by Whole Genome Sequence (WGS) were tested. Five ATCC strains were used for quality control. LFA was performed according to the kit literature, and the results were compared with those by WGS. The assay was assessed for its sensitivity and specificity for the detection of five major carbapenemases. Results A total of 87 isolates of Enterobacterales and Pseudomonas aeruginosa, characterised by WGS, were tested. Of these, 52 were positive for the big five carbapenemases (IMP, VIM, KPC, NDM, and OXA-48-like), and 35 were negative. ATCC strains were run for quality control with each batch of tests. Overall sensitivity of the assay was 98.07 per cent (51/52), with no false positives, having 100 per cent specificity (35/35). The assay correctly detected strains producing KPC, OXA-48-like, VIM, and IMP, being 100 per cent sensitive (n=33/33) when compared with WGS results; whereas, it showed delayed positivity (>15 min) to identify one strain producing NDM-1 (thus considered false negative), accounting to sensitivity of 92.3 per cent (n=12/13) for detection of NDM. It correctly identified six strains simultaneously producing OXA-48-like and NDM, and one strain producing NDM-1 and KPC. Interpretation & conclusions The assay, being robust and cost-effective, with a short turn-around-time, will prove to be a great addition to the diagnostic armamentarium, helping in implementing antimicrobial stewardship and preventing AMR.