Investigate On Resistance Mechanism And Genotype Of Carbapenem-Resistant Enterobacteriaceae Species

Objective: investigate the carbapenem-resistant mechanisn and genotype of the carbapenem-resistant enterobacteriaceae of our hospital,to provide a laboratory evidence for prevention and control the infection and outbreak of carbapenem-resistant enterobacteriaceae.To guide the clinical medical staff to use drug rationally.Methods: A total of ninty-seven enterobacteriaceae strains with resistance to meropenem,imipenem, ertapenem were collected in the First Affiliated Hospital of Dalian Medical University from January 2011 to November 2014. Bacteria identification, antibiotic sensitivity test and MIC were performed by Microscan Walkway96 SI. Modified Hodge Test was used to select strains producing carbapenemases. Whole genomic DNA was extracted.The carbapenemase gene of KPC,VIM,IMP,GES,OXA-48 was identified by PCR. PCR amplification of Class I integrase,ISCR and their variable region,comoplex class I integron,to study the distribution characteristics and dissemination of resistance genes.ERIC-PCR was established for molecular epidemiological investigation of carbapenem-resistant Enterobacteriaceae isolated from clinical samples.The aim was to provide a laboratory basis for clinical to treat the infection and epidemic of the bacterial.Results:1.Among ninty-seven strains of carbapenem-resistant enterobacteriacea,including sisty-nine Klebsiella pneumoniae, tewnty Escherichia coli,three Klebsiella oxytoca,two Proteus mirabilis, a agerogenes,a Citrobacter, an agglomerate bacilli. 2.Thirty-nine isolates were positive by Modified Hodge Test.3.The results of the carbapenemase gene: thirty-two strains were positive for KPC,accounted for 33%,twenty-one strains of VIM were positive, accounted for 21.6%,nine strains of IMP were positive, accounted for 9.3%, the gene of GES and OXA-48 were negative.4.Among ninty-seven strains of carbapenem-resistant enterobacteriaceae, sisty-two strains carried int I, accounted for 63.9%, fourty-six strains carried variable region of int I,accounted for 74.2%.Int I variable region carried five kinds of gene box combinations:including aad A1(n=32), dfr A15(n=2), aac6+arr3+drf27+aad A16(n=6),aac6(n=2), aad A2+aad B(n=4).5.Fifty-six strains were positive for orf513,accounted for 57.7%, sixteen strains carried variable region of ISCRI element, accounted for 28.6%, The variable region of ISCR element carried three kinds of gene box combinations,two strains carried ISCRI+qnr B6+qac E1+sul I, four strains carried ISCR+ qnr A1+ qac E1+ sul I, ten strains carried ISCR+qnr B2+qac E1+sul I.6.Among eighteen strains which both carried int I and ISCR, three strains were complex class l Integron,there gene box combinations were:int I+aad A1+qac E1+sul I+ISCR+qnr B2+qac E1+sul I.7.ERIC-PCR results showed that,the carbapenem-resistant klebsiella pneumoniae exist seven genotypes, ICU emergency department exist three genotypes; the carbapenem-resistant E.coli have eight genotypes, the genotypes were distribute of each departmen scatterly.Conclusion:1.The carbapenem-resistant enterobacteriaceae were mainly klebsiella pneumoniae and E.coli.The gene of carbapenem-resistant were mainly KPC and VIM.2.Intergron were mainly carry the antibiotical resistant genes of aminoglycoside antibiotics,ISCR was mainly carry the antibiotical resistant genes of quinolones.The complex class l Integron mediated multiple drug-resistant. The carbapenem-resistant enterobacteriaceae which ISCR and intergron were positive did not carry carbapenem-resistant genes.3.The carbapenem-resistant enterobacteriaceae were mainly distributed in ICU and emergency department, there may be a local trend of outbreak of epidemic.