Bacteriology
Evaluation of the RAPIDEC® CARBA NP and β-CARBA® tests for rapid detection of Carbapenemase-producing Enterobacteriaceae

https://doi.org/10.1016/j.diagmicrobio.2017.05.006Get rights and content

Highlights

  • RAPIDEC CARBA NP® (bioMérieux) and the β-CARBA NP® (Bio-Rad) tests were evaluated for the rapid detection of carbapenemase producers.

  • A panel of 149 enterobacterial isolates comprising 111 carbapenemase producers and 38 non-carbapenemase producers was used.

  • β-CARBA NP® test failed to detect all the 14 non-KPC Ambler type A producers and most (24/31) of the OXA-48-like producers.

  • RAPIDEC CARBA NP® test exhibited better performances (sensitivity 93.7%, specificity 100%) than the β-CARBA® test (sensitivity 64.9%, specificity 90%).

Abstract

The analytical performances of the RAPIDEC CARBA NP® (bioMérieux) and the β-CARBA® (Bio-Rad) tests were evaluated for the rapid detection of any known type of carbapenemases in Enterobacteriaceae. An international collection of 149 enterobacterial isolates comprising 111 Carbapenemase-Producing Enterobacteriaceae (CPE) and 38 non-carbapenemase producers was used. CPE included 32 carbapenemase producers of class A (18 KPC-2, 1 FRI-1, 5 SME and 8 IMI), 33 of class B (13 NDM, 11 VIM and 9 IMP) and 46 of class D (15 OXA-48, 14 OXA-181, 10 OXA-204, 3 OXA-232 and 4 OXA-162). The RAPIDEC CARBA NP® and the β-CARBA® tests were performed in strict accordance to the manufacturer's instructions and results were read within 2 h and 30 min, respectively. RAPIDEC CARBA NP® detected 104/111 CPE isolates compared to 72/111 for the β-CARBA® test. The overall sensitivity and specificity were 93.7% and 100%, respectively, for the RAPIDEC CARBA NP® test, and 64.9% and 90%, respectively, for the β-CARBA® test. The β-CARBA® test failed to detect all the non-KPC class A carbapenemases (14/14) and most (24/31) of the OXA-48-like producers (OXA-162, OXA-181, OXA-204 and OXA-232), and detected 1/1 OXA-163 and 1/1 OXA-405 as carbapenemase producers whereas these enzymes are rather defined as non carbapenemases. RAPIDEC CARBA NP® test exhibited better performances than those of the β-CARBA® test and confirmed to be a reliable tool for the detection of CPE, especially for OXA-48-like producers.

Introduction

The emergence and rapid dissemination of Carbapenemase-Producing Enterobacteriaceae (CPE) during the last decade represents the most worrisome event in the escalating antibiotic resistance crisis (Nordmann et al., 2011) as CPE have been reported in numerous nosocomial outbreaks worldwide. Most importantly, related infections can be treated only by a few remaining therapeutic options (Canton et al., 2012). Hence, rapid detection of CPE is of paramount importance for the timely choice of the appropriate antibiotic therapy and for the implementation of measures to prevent outbreaks.

Carbapenem resistance may arise from either (i) a concomitant reduced permeability of the outer membrane and an overexpression of enzymes with very low carbapenemase activity (e.g. extended-spectrum beta-lactamases and cephalosporinases) or (ii) the expression of enzymes with significant carbapenemase activity, defined as carbapenemases (Nordmann et al., 2012a). A large variety of acquired carbapenemases has been reported worldwide in CPE. The most prevalent carbapenemases belong to the Ambler class A (KPC), class B (VIM, IMP, and NDM) and class D (OXA-48 and OXA-48-like) (Albiger et al., 2015).

Nowadays several methods are available for the rapid detection of carbapenemase producers including: (I) molecular techniques to identify the most common carbapenemase genes (Findlay et al., 2015), (II) the MALDI-TOF technology that allows the detection of carbapenem degradation products (Hrabak et al., 2013), (III) a recently developed electrochemical assay that allows the detection of carbapenemase-producers (Bogaerts et al., 2016), (IV) immunochromatographic assays detecting KPC, IMP-like, OXA-48 and OXA-48-like β-lactamases (Glupczynski et al., 2016, Kitao et al., 2011) and (V) colorimetric assays relying on the color change of a pH indicator to detect carbapenemase activity (CARBA NP test (Nordmann et al., 2012b) and copies or derivatives (Compain et al., 2016, Noel et al., 2016, Pires et al., 2013)). Here, we compared the performances of two commercially-available colorimetric assays, the RAPIDEC® CARBA NP and the recently developed β-CARBA® test, by using a common panel of CPE.

Section snippets

Strain collection

A collection of 149 clinical enterobacterial isolates was used to assess the performances of the RAPIDEC® CARBA NP (bioMérieux, La Balme-les-grottes, France) and the β-CARBA® (Bio-Rad, Marnes-la-Coquette, France) tests. All the strains were characterized for their β-lactamase content by PCR and sequencing of the corresponding genes. The clinical isolates of worldwide origin were recovered from various clinical samples (sputum, blood cultures, urines, gut flora, etc.) and consisted in 38

Performances of the RAPIDEC® CARBA NP and β-CARBA® tests

Of the 149 tested isolates, 111 were CPE. RAPIDEC® CARBA NP yielded positive results for 104 out of the 111 CPE isolates, while the β-CARBA® test yielded positive results for only 72/111 isolates. Sensitivity and specificity of the RAPIDEC® CARBA NP test were 93.7% and 100%, respectively, values that are in good agreement with those indicated in the manufacturer's specifications (specificity 97.8% and sensitivity 97.8%). By contrast, the sensitivity and specificity of the β-CARBA® test were

Interpretation of the results

Several works have investigated the analytical performances of RAPIDEC® CARBA NP and have reported different sensitivities in detecting CPE, ranging from 90.2% to 99% (Bernabeu et al., 2017, Dortet et al., 2015a, Hombach et al., 2015, Kabir et al., 2016, Noel et al., 2016, Poirel and Nordmann, 2015). On the other hand, with the exception of the work carried out by Noël et al., where they report a value of 84% (Noel et al., 2016), the sensitivity of the RAPIDEC® CARBA NP test is always close to

Conclusion

RAPIDEC® CARBA NP test exhibited better performances than those of the β-CARBA® test and confirmed to be a reliable tool for the rapid detection of CPE. The poor performances of the β-CARBA® test were mostly due to the failure to detect the non KPC A-type carbapenemases and most OXA-48-like producers. Failure to detect most of the OXA-48-like producers by using the β-CARBA® test shall limit the value of this test in geographical areas such as in Europe where those carbapenemase producers are

Funding

This work was funded by in part by bioMérieux and in part by the University of Fribourg.

Conflict of interest

An international patent has been obtained for the Carba NP test (WO2012175637 A1). This work was partially sponsored by bioMérieux, the manufacturer of the RAPIDEC® CARBA NP.

Acknowledgments

We thank D. Uldry for her technical support.

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