NitroSpeed-Carba NP Test for Rapid Detection and Differentiation between different Classes of Carbapenemases in Enterobacterales.

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NitroSpeed-Carba NP Test for Rapid Detection and Differentiation between different Classes of Carbapenemases in Enterobacterales.

J Clin Microbiol. 2020 Jun 24;:

Authors: Nordmann P, Sadek M, Demord A, Poirel L

Abstract
A biochemical test (NitroSpeed-Carba NP test) was developed to identify carbapenemase production in Enterobacterales and to discriminate between the different types of clinically-significant carbapenemases (Ambler class A, B and D). It is based on two main features, namely the hydrolysis by all ß-lactamases including carbapenemases of the nitrocefin substrate, and the capacity of ertapenem to prevent this hydrolysis for all ß-lactamases except carbapenemases. Specific carbapenemase inhibitors of class A (avibactam, vaborbactam), class B (dipicolinic acid) and class D (avibactam) were used to inhibit the nitrocefin hydrolysis and to allow the identification of the carbapenemase types with a turn-around-time of ca. 30 min. The test was evaluated with a collection of 248 clinical enterobacterial isolates including 148 carbapenemase producers and 100 non-carbapenemase producers. Its overall sensitivity and specificity were 100% and 97.1%, respectively, including detection of all types of OXA-48-like carbapenemases. For the detection of the carbapenemase type including strains that produce double carbapenemases, the sensitivity was 100%, 97% and 100% for the detection of class A, B, and D, respectively. This easy-to-implement test may contribute to optimize the choice of the ß-lactam/ß-lactamase inhibitor combinations for treating infection due to carbapenemase producers.

PMID: 32580949 [PubMed - as supplied by publisher]