| ObjectivesTo learn the antibiotic resistance of Carbapenem-resistant Enterobacteriaceae（CRE）isolated from the Second Affiliated Hospital of Harbin Medical University.To explore the production of carbapenemase of CRE isolated from our hospital,and to elaborate the resistance mechanism of CRE.So as to provide theoretical evidence to prevent and control the infection of CRE.Methods70 strains of Carbapenem-resistant Enterobacteriaceae and were collected from July 2017 to December 2019.The sensitivity of the tested strains to clinical commonly used antibiotics was detected by K-B method and MIC methods.The phenotype confirmation test of carbapenemase was confirmed by MHT,m CIM and e CIM.PCR was used to detect common carbapenemase genes:bla KPC,bla NDM,bla IMP,bla VIM,bla OXA-48.The carbapenemase gene subtype was further determined by DNA sequencing.ResultsCRE strains were mainly Klebsiella pneumoniae（67.14%）and Escherichia coli（27.14%）.In addition,2 strains of Serratia marcescens,1 strain of Enterobacter cloacae and 1 strain of Klebsiella oxytoca were detected.70 strains of CRE were mainly distributed in surgical department（45.71%）,the isolation rete（24.28%）of Intensive Care Unit is also high,Klebsiella pneumoniae mainly isolated from sputum（46.81%）and venous blood（25.53%）samples,while Escherichia coli were isolated from urine and puncture fluid,accounting for 23.36%each.70 strains of CRE were highly resistant to penicillins,cephalosporins and quinolones,the resistance rate was higher than 86.21%,the resistance rate to Sulfamethoxazole was relatively low,it was 55.71%.Tigecyline and amikacin havestrong antibacterial activities against CRE,the drug resistance rates of were 1.43%and 25.71%,respectively.The resistance rate of Escherichia coli to various antibiotics was higher than Klebsiella pneumoniae,the resistance rate to penicillin,cephalosporin and aztreonam were 100%.Among CRE strains,only one Klebsiella pneumoniae was resistant to tigecycline.PCR detection showed that 66 strains of CRE carried the gene of carbapenems.The results of DNA sequencing showed that 31 strains only carried bla KPC-2gene,31strains only carried bla NDM-1gene,3 strains only carried bla IMP-4,11 strains carried bla KPC-2and bla IMP-4gene at the same time,one strain carried bla KPC-2and bla IMP-4at the same time,the other two strains carried bla KPC-2,bla NDM-1and bla IMP-4gene at the same time.bla VIMand bla OXA-48gene were not detected in this study.The results of phenotype screening showed that 61 CRE strains were positive in MHT test,67 CRE strains were positive in m CIM test,37 were positive in e CIM test,30 were negative in e CIM test,and 3 were unexplained because of the negative in e CIM test.ConclusionsThe CRE strains isolated in our hospital were mainly Klebsiella pneumoniae and Escherichia coli,which were mainly distributed in surgical and ICU Wards.CRE from our hospital were seriously resistant to all the antibiotics,all of them were multiple resistant strains,which were resistant to almost allβ-lactam drugs,but highly sensitive to tegacyclin and amikacin.The important resistance mechanism to carbapenem of CRE strains isolated in our hospital is the production of carbapenemases.bla KPC-2and bla NDM-1are the key carbapenemase genes responsible for mediating the resistance to carbapenem in CRE.Klebsiella pneumoniae mainly produces KPC-2,while Escherichia coli mainly produces NDM-1. |
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