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RNAi Screening to Identify Postembryonic Phenotypes in C. elegans
Published on: February 13, 2012
Evaluation of the rapid carbapenem inactivation method (rCIM): a phenotypic screening test for
Madalina-Maria Muntean1,2,3, Andrei-Alexandru Muntean3,4, Lauraine Gauthier1,2,5,6
1Research Unit EA7361 'Structure, dynamic, function and expression of broad spectrum β-lactamases', Faculty of Medicine, Université Paris-Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, France.
Objectives:
Fast and accurate diagnostic tests to identify carbapenemase-producing Enterobacteriaceae (CPE) are mandatory for proper antimicrobial therapy and implementing infection control measures. Here, we have developed a rapid Carbapenem Inactivation Method (rCIM) for CPE detection.
Methods:
The rCIM consists of the incubation of a potential carbapenemase producer with meropenem discs and use of the resulting supernatant to challenge a susceptible indicator strain. Growth of the indicator strain is monitored using a nephelometer. The performances of the rCIM were compared with the CIM and Carba NP tests using a collection of 113 well-characterized carbapenem-resistant enterobacterial isolates, including 85 carbapenemase producers and 28 non-carbapenemase producers. In addition, rCIM was compared with the Carba NP test and PCR sequencing in a prospective analysis of 101 carbapenem-resistant enterobacterial isolates addressed to the French National Reference Center for Antimicrobial Resistance in July 2017.
Results And Discussion:
The rCIM correctly identified 84/85 carbapenemase producers and 28/28 non-carbapenemase producers, yielding a sensitivity of 99% and a specificity of 100%, slightly higher than the CIM and Carba NP test. In the prospective validation study, the rCIM showed a sensitivity and specificity of 97% and 95%, respectively. Two cephalosporinase-hyperproducing Enterobacter cloacae gave false-positive results, whereas an IMI-17-producing Enterobacter asburiae gave a false-negative result. The result was, however, positive when the isolate was grown on selective antibiotic-containing media.
Conclusions:
The rCIM is a rapid (less than 3 h), cheap and accurate test for the detection of CPEs, which can be implemented in low-resource settings, making it a useful tool for microbiology laboratories.
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