Prospective evaluation of the OKN K-SeT assay, a new multiplex immunochromatographic test for the rapid detection of OXA-48-like, KPC and NDM carbapenemases

Abstract

Objectives: There is an urgent need for accurate and fast diagnostic tests capable of identifying carbapenemase producers. Here, we assessed the performance of a new multiplex lateral flow assay (OKN K-SeT) for the rapid detection of OXA-48-like, KPC and NDM carbapenemase-producing Enterobacteriaceae from culture colonies.

Methods: Two hundred collection isolates with characterized β-lactamase content and 183 non-duplicate consecutive isolates referred to two National Reference Centres over a 2 month period in 2016 were used to evaluate the OKN K-SeT assay.

Results: The assay correctly detected all 42 OXA-48-like-, 27 KPC- and 30 NDM-producing isolates from the collection panel, including 7 isolates that co-produced NDM and OXA-181 carbapenemases. No cross-reactivity was observed with non-targeted carbapenemases ( n =  41) or with non-carbapenemase producers ( n =  60). Prospectively, all OXA-48-like ( n =  69), KPC ( n =  9) and NDM ( n =  19) carbapenemase-producing Enterobacteriaceae isolates were correctly detected, while 11 carbapenemase producers not targeted by the assay went undetected [VIM ( n =  8) and OXA-23/OXA-58-like ( n =  3)]. Overall, the sensitivity and specificity of the assay were 100%.

Conclusions: The OKN assay is efficient, rapid and easy to implement in the workflow of a clinical microbiology laboratory for the confirmation of OXA-48, NDM and KPC carbapenemases. This test represents a powerful diagnostic tool as it enables the rapid detection of the most clinically important carbapenemases without the need for more costly and less frequently available molecular assays.