Comparative Evaluation of Four Phenotypic Tests for Detection of Carbapenemase-Producing Gram-Negative Bacteria

Abstract

Four screening assays aimed for rapid detection of carbapenemase production from Gram-negative bacterial isolates, i.e., the Neo-Rapid Carb kit (Rosco Diagnostica A/S), the Rapidec Carba NP test (bioMérieux SA), the ␤ Carba test (Bio-Rad Laboratories N.V.), and a homemade electrochemical assay (BYG Carba test) were evaluated against a panel comprising 328 clinical isolates (Enterobacteriaceae [n ϭ 198] and nonfermentative Gram-negative bacilli [n ϭ 130]) with previously characterized resistance mechanisms to carbapenems. Among Enterobacteriaceae isolates, the BYG Carba test and the ␤ Carba test showed excellent sensitivities (respectively, 100% and 97.3%) and specificities (respectively, 98.9% and 97.7%). The two other assays yielded poorer performances with sensitivity and specificity of 91.9% and 83.9% for the Rapidec Carba NP test and of 89.2% and 89.7% for the Neo-Rapid Carb kit, respectively. Among Pseudomonas spp., sensitivities and specificities ranged, respectively, from 87.3% to 92.7% and from 88.2% to 94.1%. Finally, all tests performed poorly against Acinetobacter spp., with sensitivities and specificities, respectively, ranging from 27.3% to 75.8% and from 75 to 100%. Among commercially available assays, the ␤ Carba test appeared to be the most convenient for routine use and showed the best overall performances, especially against OXA-48-like producers. The excellent performance of the BYG Carba test against Enterobacteriaceae was confirmed (100% sensitivity and 98.9% specificity).

Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry for the Rapid Detection of Antimicrobial Resistance Mechanisms and Beyond

“…The BYG Carba test has proven to be highly sensitive for discriminating between carbapenemase producers and nonproducers. It has the advantage of delivering results in 30 min without incubation at 37°C, and the sensitivity and specificity are higher than those of biochemical assays, although this requires further clinical validation (34)(35)(36). For the moment, the electrodes, the reader, and the software are made in-house and are not commercially available.…”

Evaluation of MASTDISCS combi Carba plus for the identification of metallo‐β‐lactamases, KPC and OXA‐48 carbapenemase genes in Enterobacteriaceae clinical isolates

“…Carbapenems are often considered last resort antibiotics in the treatment of infections due to multidrug‐resistant Enterobacteriaceae clinical isolates, since they are stable even in response to extended‐spectrum β‐lactamases (ESBLs) and AmpC enzymes (Tsakris et al ; Jean et al ; Carrasco‐Anabalón et al ; Wang et al ). However, the carbapenem resistance has been increasingly reported among Enterobacteriaceae in the past few years, which is largely attributed to the production of metallo‐β‐lactamases (MBLs), KPC and OXA‐48 (Yusuf et al ; Tijet et al ; Noël et al ; Tamma and Simner ). Therefore, the dissemination of carbapenemase‐producing Enterobacteriaceae (CPE) has been a serious public health problem of global scale, and the early detection of CPE is essential for targeted antimicrobial therapy as well as for effective and timely infection control.…”

Multicentre evaluation of the BYG Carba v2.0 test, a simplified electrochemical assay for the rapid laboratory detection of carbapenemase-producing Enterobacteriaceae

“…A signal cut-off of 3.5 and of 11.5 (arbitrary units [AU]) was defined as the threshold for discrimination between carbapenemase and non-carbapenemase producers for the BYG v1.0 and BYG v2.0, respectively and were established previously using ROC curve 4 , 5 .…”

“…The procedure used with BYG Carba v2.0 is very simple (supplementary video). Among commercial tests only the β-CARBA ™ Test from Bio-Rad offers similar advantages with minimal hands-on time and low bacterial inoculum but detection remains based on visual detection of a colour change 4 . In the laboratory, the cost for a BYG Carba test prototype seems affordable.…”

“…The most rapid methods rely on the detection of carbapenem hydrolysis by colorimetric assay or by mass spectrometry 3 . We recently evaluated three colorimetric assays, the RAPIDEC ® CARBA NP test (BioMérieux, Marcy l’Etoile, France), the Neo-Rapid CARB kit (Rosco Diagnostica, Taastrup, Denmark) and the β-CARBA ™ test (Bio-Rad, Marnes-la-Coquette, France) and found that overall all these tests showed satisfactory results for the detection of CPE despite differences in performance between the tests 4 . Nevertheless, all the colorimetric assays are based on a subjective visual observation of colour change, which can be sometimes challenging to interpret, especially for some carbapenemase families (e.g: OXA-48 like, GES-like) with lower hydrolytic activity.…”