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Detection of carbapenem resistance by the Reveal™ rapid phenotypic AST assay in strains from the CDC and FDA antimicrobial resistant isolate bank
ESCMID eLearning. Singh P. 07/09/21; 328652; 2277
Pragya Singh
Pragya Singh
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Abstract
Discussion Forum (0)
Abstract number: 2277

Session Type: ePosters

Session Title: ePosters

Authors(s): L. Rajeev, K. Khomtchouk, P. Singh, P. Rhodes

Authors Affiliations(s): Specific Diagnostics, United States

Background:

Carbapenem-resistant Gram-negative bacteria, “superbugs”, are one of the world’s great healthcare threats. The CDC has partnered with the FDA to compile a unique library of these organisms and made them available to foster the development of diagnostic assays and therapeutics suited to address this threat.  Here, we evaluated the performance of the Reveal rapid AST with 317 carbapenem-resistant organisms from the CDC AR isolate bank, and compared the results to the sensitivity with which carbapenem resistance could be predicted by the 5 carbapenemase targets (KPC, NDM, IMP, VIM and Oxa-48-like) present on widely available PCR panels.

Methods:

The Reveal AST system calls phenotypic MICs using an array of small molecule sensors highly sensitive to the volatile organic compounds emitted during microbial growth.  All the CDC carbapenem-resistant strains were spiked into blood culture bottles and the positive blood culture sample was diluted and inoculated into 96-well dried antibiotic plates (MicroScan, Beckman Coulter). The plates were sealed with the Reveal sensor panel and run on the Reveal system, which images sensor responses every 10 minutes seeking indication of growth in each well.  A carbapenem resistant phenotype was called if the Reveal found the strain to be resistant to at least one of either imipenem, ertapenem, or meropenem per the CDC-furnished antibiogram.  We verified the CDC antibiogram with Sensititre (Thermo Fisher) and found it to be correct in all cases. To compare the potential sensitivity of the PCR panels, we utilized the resistome furnished by the CDC, assumed the PCR panel had 100% sensitivity, and identified whether one or more of the carbapenemase targets were present in each sample. 

Results:

Reveal detected carbapenem resistance in 312/317 (98.4%) CDC AR bank carbapenem-resistant isolates, across all Gram-negative species tested (Figure 1). Reveal reported carbapenem resistance in 204/205 (99.5%) of the carbapenamase-producing isolates and 108/112 (96.4%) of the non-carbapenamase-producing organisms. The PCR panels would, assuming 100% sensitivity, detect only 62.8% (205/317) of the carbapenem-resistant strains (Figure 1). 

Conclusions:

We conclude that the diversity of genomic mechanisms responsible for resistance to carbapenems requires a rapid phenotypic test, and that Reveal is highly effective at detecting this clinically important phenotype. 

Keyword(s): Reveal rapid AST, carbapenem resistance, multidrug resistant organisms

Abstract number: 2277

Session Type: ePosters

Session Title: ePosters

Authors(s): L. Rajeev, K. Khomtchouk, P. Singh, P. Rhodes

Authors Affiliations(s): Specific Diagnostics, United States

Background:

Carbapenem-resistant Gram-negative bacteria, “superbugs”, are one of the world’s great healthcare threats. The CDC has partnered with the FDA to compile a unique library of these organisms and made them available to foster the development of diagnostic assays and therapeutics suited to address this threat.  Here, we evaluated the performance of the Reveal rapid AST with 317 carbapenem-resistant organisms from the CDC AR isolate bank, and compared the results to the sensitivity with which carbapenem resistance could be predicted by the 5 carbapenemase targets (KPC, NDM, IMP, VIM and Oxa-48-like) present on widely available PCR panels.

Methods:

The Reveal AST system calls phenotypic MICs using an array of small molecule sensors highly sensitive to the volatile organic compounds emitted during microbial growth.  All the CDC carbapenem-resistant strains were spiked into blood culture bottles and the positive blood culture sample was diluted and inoculated into 96-well dried antibiotic plates (MicroScan, Beckman Coulter). The plates were sealed with the Reveal sensor panel and run on the Reveal system, which images sensor responses every 10 minutes seeking indication of growth in each well.  A carbapenem resistant phenotype was called if the Reveal found the strain to be resistant to at least one of either imipenem, ertapenem, or meropenem per the CDC-furnished antibiogram.  We verified the CDC antibiogram with Sensititre (Thermo Fisher) and found it to be correct in all cases. To compare the potential sensitivity of the PCR panels, we utilized the resistome furnished by the CDC, assumed the PCR panel had 100% sensitivity, and identified whether one or more of the carbapenemase targets were present in each sample. 

Results:

Reveal detected carbapenem resistance in 312/317 (98.4%) CDC AR bank carbapenem-resistant isolates, across all Gram-negative species tested (Figure 1). Reveal reported carbapenem resistance in 204/205 (99.5%) of the carbapenamase-producing isolates and 108/112 (96.4%) of the non-carbapenamase-producing organisms. The PCR panels would, assuming 100% sensitivity, detect only 62.8% (205/317) of the carbapenem-resistant strains (Figure 1). 

Conclusions:

We conclude that the diversity of genomic mechanisms responsible for resistance to carbapenems requires a rapid phenotypic test, and that Reveal is highly effective at detecting this clinically important phenotype. 

Keyword(s): Reveal rapid AST, carbapenem resistance, multidrug resistant organisms

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