Clinical application of mCIM and eCIM combined detection of carbapenemase-producing enterobacteriaceae

Abstract

Objective: To explore the clinical application value of modified carbapenem inactivation test (mCIM) combined with EDTA-modified carbapenem inactivation test (eCIM) for detecting the carbapenemase of CRE isolated from infected patients in clinical diagnosis and infection control of CRE infection. Methods: Drug resistance of seventy eight non-repetitive enterobacteriaceae resistant to carbapenem antibiotics, which were isolated from clinically infected patients from January 2017 to December 2017 in the Tianjin Medical University General Hospital, was retrospectively analyzed. Meanwhile, Vitek2 Compact automatic bacterial identification instrument was used to identify the species and detect its minimum inhibitory concentration (MIC) for ertapenem and imipenem. Carbapenemase genes blaKPC, blaNDM, blaIMP and blaVIM were detected by PCR test, the genotype was determined by gene sequencing as the gold standard, and mCIM Combined eCIM test was used for carbapenemase detection of collected bacteria. Using PCR results as the standard, the sensitivity, specificity, positive predictive value, negative predictive value and Cohen' Kappa value of mCIM and eCIM were calculated, and the consistency of the combined detection results of mCIM and eCIM and PCR results was checked. Results: Seventy eight carbapenem-resistant Enterobacteriaceae were detected by PCR, 74 carbapenemase gene positive and 4 negative, including 60 blaKPC-2 positive, 2 blaNDM-1 positive and blaNDM-5 positive Of the 7 strains, 3 strains were positive for blaNDM-9, 1 strain was positive for blaIMP-4, and 1 strain was both positive for blaKPC-2 and blaNDM-1. The sensitivity of mCIM to detect carbapenemase is 100%, the specificity is 100%, and the Kappa value is 1.000; the combined detection of mCIM and eCIM for serine carbapenemase has a sensitivity of 100%, the specificity is 100%, and the Kappa value is 1.000; The sensitivity of combined detection of metallo-β-lactamase is 92.9%, the specificity is 100%, and the Kappa value is 0.955. Conclusions: The combined test of mCIM and eCIM which is used to detect carbapenemase in CRE costs low, doesn't require special reagents and equipment, has strong practicability, simple operation, and easy interpretation of results. According to the different genotypes of CRE bacteria, it provides important clinical diagnostic evidence for clinical CRE diagnosis, precise antimicrobial treatment and infection control.