| Objectives:To screen Carbapenem-Resistant Enterobacteriaceae in The First Affiliated Hospital of KunMing Medical University,investigate the phenotype, molecular characterization,and colonization of CRE;Understand the Clinical Infection Charaeteristies,such as distribution in strains,specimens, department,and the risk factors associated with CRE,provide guidance for standard medication and infection controls.Methods:①Clinical strains were collected between December 2011 and December 2014, identification and susceptibility test were completed by VITEK-2 system, which is necessary to screen CRE,then Modified Hodge test (MHT) recommended by CLSI were used to identify the phenotype of CRE, at the same time, metallo-β-lactamases (MBL) and extended spectrum β-lactamases (ESBLs) phenotype confirmation tests were used to detect the hydrolase produced by resistant strains;②Specific PCR amplication were applied to analyze the resistance gene of carbapenemase (KPC-2,SME,IMP,VIM,NDM-1,OXA-48) and ESBLs(SHV,TEM, CTX-M),followed by DNA sequencing,to discuss the molecular epidemiology of CRE;③The homology of strains was analyzed by repetitive intergenic sequence based polymerase chain reaction (ERIC-PCR) to reflect the clone transmission of CRE, the resulting band patterns were compared visually, isolates with more than a two-band difference were categorized as different clone types, those with identical band patterns or that differed by less than two bands were considered indistinguishable or closely related;④Analyze the distribution of CRE in strains,specimens, department,along with prevalence of resistance gene,to reveal the Clinical Infection Charaeteristies;⑤At the same time,the patients infected with Carbapenem Resistant Enterobacteriaceae were acted as cases(CRE), the patients infected with Carbapenem Susceptible Enterobacteriaceae (CSE) were acted as controls, the case information both CRE and CSE patients were reviewed, mainly include sex, age, comorbidities, use of invasive devices, exposure to antibiotics, Prior corticosteroid use, Length of hospital stay,costs during hospital and outcomes,variables were statisticed by univariate and multi-univariate analysis to identify the main risk factors associated with CRE in clinical.Results:①The results of antimicrobial susceptibility testing showed the resistance rate of Cephalosporins and relevant β-lactamase inhibitors were more than 90%,Quinolones(80%), Amikacin (60.6%), even Carbapenems higher than 75%,which is characterized by multi-drug resistant, Tetracycline(31.4%) is the lowest of tested antibiotics for its lower utility ratio of prescriptions ②correlation analysis of Phenotype and resistance gene detection found 87.4% of CRE were positive in MHT, which has been reported to be 100% sensitive for the detection of KPC-2, although PCR showed positive rate of class A carbapenemase KPC-2was 61.6%; MBL phenotype were identified positive in 33% of CRE,however, MBLresistance gene IMP-4, NDM-1 present different positive rate of 50.5% and 19.4%;similarly,42.7% of strains were detected in ESBLs confirmation tests, TEM-1, SHV-12andCTX-M-15with positive rate of 85.4%,71.3% and 21%,respectively; obviously traditional phenotype test were seriously inconsistent with specific PCR,this may related to complex drug-resistance mechanisms and different sensitivity and specficity were existed in the tested phenotype confirmation;thus,it can’t accurately reflect the resistance gene carried by CRE,but in some institution unqualified to develop PCR,phenotype identification is necessary to screen CRE.③ERIC-PCR demonstrated two clone types were found in most of the CRE,125 of Klebsiella pneumonia and 10 of Citmbacter freund are of the same clonal Type, the other 31 differed with two bands, maybe a subtype,it revealed clonal dissemination could have happened in different genus of Enterobacteriaceae,as the same clonal CRE usually distuibuted in EICU,ICU and Transplantology etal, which may enlarge the transmission of CRE;in addition,6 Enterobacter cloacae and 2 Escherichia coli belong to a newbanding patterns,which increase the difficulty of infection controls.④ Results of Clinical Infection Charaeteristies showed 206 CRE were identied in all,Klebsiella pneumonia(71%) is the most common of the strains,followed by Citmbacter freund(10%), Escherichia coli(9.7%), Enterobacter cloacae (4.4%) and others(4.9%), patients were mainly distributed in the department of EICU (33.5%)、 ICU (13.6%) and Transplantology(18%), at the same time,cultures were obtained mainly from sputum(44.7%) and urine(33%);⑤By univariable analysis,Variables analyzed as risk factors included the use of antibiotics (β-lactamase/inhibitor, Meropenem,Vacomycin, Tigercline, Imipenem and Cilastatin Sodium),Mechanical ventilation,hypertension, multiple organ dysfunction syndrome (MODS),Cortisone administration,Length of hospital stay, Total costs and sex; By multi-univariable analysis revealed Meropenem, multiple organ dysfunction syndrome (MODS), hypertension,sex and the total charges are independent riskfactors for CRE.Conclutions:①CREwere highly resistant to the majority of antibiotics tested,even carbapenems with a resistantce rate of more than 75%,obviously characterized by multi-drug resistant(MDR);② Combined phenotype identification with PCR test showed complex resistant mechanism of hydrolase production, meanwhile,various resistance gene always carried by the same strains;③ ERIC-PCR demonstrated clonal dissemination not only have happened in different genus of Enterolacteriaceae but also in some critical departments of our hospital,which is urgent to control;④ Analyze of Clinical Infection Charaeteristies indicates the CRE increased rapidly from 0.8% to 7.7% in our hospital during 2011-2014,71% of them are Klebsiella pneumonia,cultures were obtained mainly from sputum(44.7%) and urine(33%),most of the CRE are collected from EICU,ICU and Transplantology;⑤Meropenem, multiple organ dysfunction syndrome (MODS), hypertension,sex and the total charges are independent risk factors for CRE. |
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