Study On Risk Factors Of Carbapenem-resistant Enterobacter Infection In Intensive Care Unit

Objectives: To analyze the infection risk factors and transmission mechanism of carbapenem-resistant Enterobacteriaceae(CRE)in intensive care unit(ICU).The purpose of this study was to reveal the mechanism of widespread spread of strains through combining molecular biological techniques and clinical epidemiological investigation,so as to provide laboratory and clinical basis for taking effective nosocomial infection control measures and curbing the persistent infection and outbreak caused by these strains in time.Methods: A total of 196 patients with nosocomial infection who were hospitalized in ICU of Zhongshan People’s Hospital from January 2016 to June 2019 were selected retrospectively.According to the results of CRE detection,patients with CRE infection were divided into CRE group(35 cases)and carbapenem sensitive group(control group,161 cases).The distribution and drug resistance characteristics of CRE pathogens ICU were analyzed.We also collected the clinical data of relevant patients and used Multiple Logistic Regression to analyze the risk factors of CRE infection of patients in ICU.At the same time,PCR was used to detect drug-resistance genes of CRE,Pulsed Field Gel Electrophoresis was used,PFGE)and the extragenic palindromic-polymerase Chain Reaction REP-PCR showed a significant increase in the incidence of carbapenem-resistant Klebsiella pneumonia(CR-KPN)and carbapenem-resistant E coli(Carbapenem-resistant E.CREC)for homology analysis.Results: A total of 35 CRE positive cases were found,with the infection rate of17.86%(35/196).68 strains of Klebsiella pneumoniae were detected,which was found the highest positive rate(52.94%).CRE strains were resistant to cephalosporins,penicillins,carbapenems and other antibiotics in varying degrees,but were sensitive to polymyxin and tigecycline.Univariate analysis showed that the age,APACHE II score at admission to ICU,ICU hospitalization time,mechanical ventilation period,proportion of indwelling catheter,proportion of hemodialysis,proportion of carbapenem antibiotics,proportion of cephalosporins antibiotics and proportion of combined use of drugs in the CRE group were higher than those in the control group.Multivariate Logistic regression analysis showed that APACHE II score≥20,carbapenem antibiotics,combination therapy,mechanical ventilation period ≥ 3 days and ICU hospitalization period ≥ 10 days were the risk factors of CRE infection in ICU patients.Among the 58 strains of CRE,38 strains were KPC positive,with a positive rate of65.51%.Sequencing confirmed that all strains were KPC-2 subtype.Twelve strains were positive for NDM gene,and the positive rate was 20.68%,which were confirmed by sequencing as NDM-1 subtype.8 strains were positive for SHV gene,and the positive rate was 13.79%.Homology of CR-KPN was found in six clones,Clone A,involving four patients;The lower respiratory isolates of patient 2 and patient 4 belonged to clone B.The clinical isolates from the other patients were all different clones.REP-PCR was used to analyze the homology of CREC,and only 3 of the 17 patients had similar electrophoresis patterns,suggesting possible homology.Conclusions: The risk factors of CRE infection in ICU are high infection rate,severe illness,exposure history of carbapenem antibiotics,combined use of multiple antibiotics,prolonged mechanical ventilation and hospital stay.The CRE resistant machines in our hospital mainly carried KPC and NDM carbapenemase genes.The results of homology analysis showed that the nosocomial infection in ICU of our hospital was well controlled,the management was in place,and the cross infection between patients rarely happened.