Abstract
This study aimed to design a new method for rapid and accurate detection of carbapenemase phenotypes based on the simplified carbapenem inactivation method (sCIM). We evaluated the sensitivity and specificity of the method, called the rapid carbapenemase detection method (rCDM), for the detection of carbapenemase-producing Enterobacteriaceae and Pseudomonas aeruginosa. A total of 257 Enterobacteriaceae, 236 P. aeruginosa, and 20 Acinetobacter baumannii isolates were tested. Phenotypic evaluations were performed using rCDM, sCIM, and mCIM. For Enterobacteriaceae, the sensitivity of rCDM was 100% and the specificity was 99.6%. For P. aeruginosa, the sensitivity of rCDM was 97.4% and the specificity was 100%. Carbapenemase-producing A. baumannii were not detected by rCDM. The concordance rate of rCDM and sCIM for Enterobacteriaceae and P. aeruginosa was 99.8%, with the exception of one P. aeruginosa isolate that expressed the blaVIM−4 gene. The concordance rate of rCDM and mCIM for Enterobacteriaceae and P. aeruginosa was 100%. rCDM can be used to accurately detect carbapenemase-producing Enterobacteriaceae and P. aeruginosa in 5–6 h and is suitable for routine use in most clinical microbiology laboratories.
Highlights
Carbapenemase-producing Gram negative bacilli are a major problem worldwide (Gupta et al., 2011)
McNemar test was used to examine the difference in the test results between rapid carbapenemase detection method (rCDM) and the three existing methods (PCR, simplified carbapenem inactivation method (sCIM), and modified carbapenem inactivation method (mCIM)), and the Kappa coefficients were further provided to indicate the degree of consistency
Of the 57 non-carbapenemase-producing Enterobacteriaceae, only one isolate was found to be positive by rCDM
Summary
Carbapenemase-producing Gram negative bacilli are a major problem worldwide (Gupta et al., 2011). The FDA recommends methods such as matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and other improved methods (Burckhardt and Zimmermann, 2011; Lee et al, 2013; Sun et al, 2017; Muntean et al, 2018). These procedures are lengthy (mCIM and eCIM require 24 h to detection), require expensive equipment such as MALDI-TOF MS, or involve reagents that cannot be stored for long periods of time (Carba NP, CarbaNP solution B can be stored in solution at 4–8◦ C for up to 3 days) (Burckhardt and Zimmermann, 2011; CLSI, 2018). In order to detect carbapenemaseproducing strains in a shorter time, we have designed a new detection method, the rapid carbapenemase detection method (rCDM), that can detect carbapenemase-producing
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