Rapid identification of carbapenemase-producing Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii using a modified Carba NP test

Bakour, Sofiane; Garcia, Vincent; Loucif, Lotfi; Brunel, Jean‐Michel; Gharout-Sait, Alima; Touati, Abdelaziz; Rolain, Jean‐Marc

doi:10.1016/j.nmni.2015.07.001

Cited by 68 publications

(38 citation statements)

References 11 publications

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“…Overall, the performance statistics were consistent with those in prior publications, including issues noted with isolates expressing OXA-48-like carbapenemases and OXA genotypes found in the Acinetobacter baumannii complex (4,6). In 2015, Bakour et al described a universal and improved bacterial cell lysis that offered improved performance with OXA genotypes found in the A. baumannii complex (24). These data were not available at the time of our study, and we were not able to evaluate the method improvements proposed by Bakour et al (24).…”

Section: Discussionsupporting

confidence: 83%

“…In 2015, Bakour et al described a universal and improved bacterial cell lysis that offered improved performance with OXA genotypes found in the A. baumannii complex (24). These data were not available at the time of our study, and we were not able to evaluate the method improvements proposed by Bakour et al (24). Despite the necessity for participating laboratories to prepare the bulk of the reagents, there was a high degree of consistency in accuracy across all seven sites.…”

Section: Discussionmentioning

confidence: 84%

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Multicenter Performance Assessment of Carba NP Test

et al. 2017

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Eighty Gram-negative bacilli (54 Enterobacteriaceae and 26 nonfermenting Gram-negative bacilli) obtained from multiple institutions in the United States were distributed in a blinded manner to seven testing laboratories to compare their performance of a test for detection of carbapenemase production, the Carba NP test. The Carba NP test was performed by all laboratories, following the Clinical and Laboratory Standards Institute (CLSI) procedure. Site-versus-site comparisons demonstrated a high level of consistency for the Carba NP assay, with just 3/21 site comparisons yielding a difference in sensitivity (P Ͻ 0.05). Previously described limitations with bla OXA-48-like carbapenemases and bla OXA carbapenemases associated with Acinetobacter baumannii were noted. Based on these data, we demonstrate that the Carba NP test, when implemented with the standardized CLSI methodology, provides reproducible results across multiple sites for detection of carbapenemases.KEYWORDS carbapenemase, antimicrobial resistance, screening, Gram-negative bacilli C linical microbiology laboratories around the globe have instituted a range of rapid screening tests for detection of carbapenemase production in the rising tide of carbapenem-nonsusceptible Gram-negative bacilli (GNB). One method, the Carba NP test, offers a rapid and simple colorimetric method for the detection of carbapenemase activity in isolates of GNB. In principle, the test is similar to the classic ␤-lactamase detection assays described by Escamilla and by Skinner and Wise in the 1970s, in which benzylpenicillin acidimetrically produced a red color after hydrolysis by Haemophilus influenzae ␤-lactamase (1, 2). With the Carba NP test, hydrolysis of imipenem produces acid and drives the pH indicator, phenol red, from red to yellow.The Carba NP test has been studied by several investigators (3-14), including evaluations and comparisons to a commercial version (15)(16)(17)(18)(19)(20). However, the literature lacks consistency in the Carba NP methodology. The test has evolved several times, including alterations to reagents, and has gone from a microtiter plate-based format performed on bacterial protein extracts to a rapid tube-based test with abbreviated processing. Most studies have been single-laboratory evaluations; there is a lack of multicenter performance assessments utilizing a single, harmonized method.As part of an effort to standardize the method, the Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 84%

Multicenter Performance Assessment of Carba NP Test

et al. 2017

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“…The former included commercial kits, such as Rapidec Carba NP (package insert version 98024-04/03/2016; bioMérieux, Marcy-l'Étoile, France), Neo-Rapid Carb screen kit (package insert version DBV0040F-01/11/2013; ROSCO Diagnostica, Taastrup, Denmark), and Rapid Carb Blue screen (package insert version DBV0-04/09/2014; ROSCO Diagnostica, Taastrup, Denmark), as well as manual methods requiring reagent preparation, such as the manual Carba NP CLSI method (10), manual Blue Carba (11), and modified Carba NP (12). All methods were performed as previously described or by following the package inserts for the commercial-based assays.…”

Section: Methodsmentioning

confidence: 99%

Comparison of 11 Phenotypic Assays for Accurate Detection of Carbapenemase-Producing Enterobacteriaceae

et al. 2017

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Early identification of carbapenemase-producing Enterobacteriaceae (CPE) is essential to prevent their dissemination within health care settings. Our objective was to evaluate the accuracy of 11 phenotypic assays for the detection of CPE. Two collections of carbapenem-resistant Enterobacteriaceae (CRE) isolates were evaluated, including 191 retrospective isolates (122 CP-CRE and 69 non-CP isolates) as well as 45 prospective clinical isolates (15 CP-CRE and 30 non-CP-CRE) obtained over a 3-month period. The sensitivity and specificity of each test was determined, with molecular genotype serving as the gold standard. Among the retrospective cohort, sensitivities ranged from 72% for the boronic acid synergy test for the detection of KPC producers to Ն98% for the modified Carba NP, the Rapidec Carba NP, the manual Blue Carba, and the modified carbapenem inactivation method for the detection of any CPE. Sensitivity differed among tests across enzyme classes. All assays had excellent specificity exceeding 95%, with the exception of the boronic acid synergy test (88%) and modified Hodge test (91%). Prospectively, 45 CRE isolates were encountered over a 3-month period, including 15 CPE (33%) and 30 non-CP-CRE (67%). Results from the prospective cohort were similar. However, a decrease in specificity was observed across most tests, likely due to restricted inclusion of non-CP-CRE to assess the specificity of the assays. Overall, accuracy of CPE detection varied across phenotypic tests. Local epidemiology of CP genotypes, turnaround time, and ease of incorporation into the laboratory workflow should be considered when selecting a phenotypic assay for clinical use.KEYWORDS carbapenem-resistant organisms, carbapenemase-producing organisms, prevalence C arbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are associated with significant morbidity and mortality (1, 2). A variety of carbapenemase genes have been described that are either plasmid or chromosomally encoded, including bla KPC , bla SME , bla IMI , bla NDM , bla VIM , bla IMP , and bla OXA-48-type (2). Early and accurate identification of CP-CRE is essential to prevent their dissemination within health care settings.Detection of CP-CRE in clinical laboratories is challenging, as isolates may only have moderate reductions in susceptibilities to carbapenems (3), and resistance may be mediated by other mechanisms, such as extended-spectrum-␤-lactamase (ESBL) and/or AmpC ␤-lactamase producers with decreased membrane permeability. Molecular methods for the detection of carbapenemase genes are costly, may require significant expertise, and are limited by the targets included. Thus, rapid and affordable phenotypic assays to broadly classify CRE into CP-CRE versus non-CP-CRE have been developed.

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“…The extraction method was further modified to produce a single extraction reagent that could be used for CRE, Pseudomonas, and Acinetobacter species. The resulting modified Carba NP assay uses 0.02% cetyltrimethylammonium bromide for extraction and a starting pH of 7.5 (previously 7.8) (59). The modified Carba NP assay, performed on a variety of carbapenemase producers (including OXA-23 and OXA-40) among both CPE and CP-NF, has a reported sensitivity and specificity of 100% (59).…”

Section: Rapid Colorimetric Carbapenemase Assaysmentioning

confidence: 99%

“…The resulting modified Carba NP assay uses 0.02% cetyltrimethylammonium bromide for extraction and a starting pH of 7.5 (previously 7.8) (59). The modified Carba NP assay, performed on a variety of carbapenemase producers (including OXA-23 and OXA-40) among both CPE and CP-NF, has a reported sensitivity and specificity of 100% (59). Last, the Blue-Carba assay is a version of the Carba NP test that utilizes bromothymol blue as a pH indicator, a lower starting pH, and no extraction step.…”

Section: Rapid Colorimetric Carbapenemase Assaysmentioning

confidence: 99%

Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

2016

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The non-glucose-fermenting Gram-negative bacilli Pseudomonas aeruginosa and Acinetobacter baumannii are increasingly acquiring carbapenem resistance. Given their intrinsic antibiotic resistance, this can cause extremely difficult-to-treat infections. Additionally, resistance gene transfer can occur between Gram-negative species, regardless of their ability to ferment glucose. Thus, the acquisition of carbapenemase genes by these organisms increases the risk of carbapenemase spread in general. Ultimately, infection control practitioners and clinical microbiologists need to work together to determine the risk carried by carbapenem-resistant non-glucose-fermenting Gram-negative bacilli (CR-NF) in their institution and what methods should be considered for surveillance and detection of CR-NF.

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Rapid identification of carbapenemase-producing Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii using a modified Carba NP test

Cited by 68 publications

References 11 publications

Multicenter Performance Assessment of Carba NP Test

Multicenter Performance Assessment of Carba NP Test

Comparison of 11 Phenotypic Assays for Accurate Detection of Carbapenemase-Producing Enterobacteriaceae

Carbapenem-Resistant Non-Glucose-Fermenting Gram-Negative Bacilli: the Missing Piece to the Puzzle

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