Laboratory Research And Changes Of Antimicrobial Resistance Of Carbapenem-resistant Enterobacteriaceae

Objectives:To research clinical features, epidemiology, detection methods of NDM-1-producing carbapenemase of Enterobacteriaceae infection in patients and analysis of strains of homology. To investigate the distribution, changes and mechanism of antibiotic resistance of Enterobacteriaceae bacteriain in ICU from2008to2013. To discuss the best concentration of Meropenem-EDTA Disk Test with different concentrations of EDTA for screening metallo-beta-lactamases in Enterobacteriaceae.Methods:1. Review the type of strains of NDM-1-producing carbapenemase and antimicrobial susceptibility were determined by K-B and E-test.2. The ESBLs phenotypic screening test and Modified Hodge test (MHT) were used for the detection of carbapenemase and EDTA-disc synergy test and E-test were used for the detection of metalloenzymes.3. Potymerase chain reaction (PCR) was used for the detection of KPC, SME, IMP, VIM, NDM-1and OXA-48gene.4. Analyze clinical datas of NDM-1-producing carbapenemase of Enterobacteriaceae infection in patients.5. The quantity, classification and susceptibility datas were analyzed by WHONET5.5software.6. The efflux inhibition test was finished by CCCP.7. Meropenem-EDTA Disk Test with different concentrations of EDTA was used for screening metallo-beta-lactamases.Results:1. The major component of Enterobacteriaceae of NDM-1-producing carbapenemase was Klebsiella pneumoniae and mostly from the ICU ward. Antimicrobial drugs were almost resistant except AK, CN, CHL, TET and LEV. Enterobacteriaceae of NDM-1-producing carbapenemase was local popular in our hospital, especially the ICU.2. A total of1027Enterobacteriaceae bacterias were separated in ICU for6yeas. Klebsiella pneumoniae and Escherichia coli are the main pathogens, including16pairs of carbapenem antimicrobial resistance and8strains producing NDM-1carbapenemase.3. The specificity of MEN/EDTA (1mol/L、0.5mol/L、0.4mol/L、0.2mol/L、0.1mol/L.0.05mol/L) is20%、40%、60%、60%、100%、100%, but the sensitivity is100%.Conclusions:1. Enterobacteriaceae of NDM-1-producing carbapenemase was the main type in our hospital, and has been local epidemic in ICU in our hospital.2. Meropenem-EDTA Disk Test for screening metallo-beta-lactamases is easy to operate, rapid, high sensitivity and suitable for general microbiological testing to detect metal enzymes, especially NDM-1-producing strain.When the standard interpretation is≥5mm for screening metallo-beta-lactamases in Enterobacteriaceae, The specificity and sensitivity of MEN/EDTA (0.1mol/L,10ul) is100%. Therefore, we recommend using lOul0.1mol/L EDTA.