Drug Resistance And Molecular Characterization Of Carbapenem-resistant Enterobacter Cloacae

Objective:To understand the drug resistance,microbial characteristsics and resistance mechanisms so as to provide effective control measures and a reasonable basis for the clinical treatment.Methods:866 strains of Enterobacter cloacae were collected in the clinical specimens isolated from January 2013 to December 2016.These strains were tested for drug susceptibility using the paper diffusion method(K-B method).According to the CLSI standard,the results of drug resistance were analyzed and 21 strains of carbapenem antibiotics resistant to Enterobacter cloacae were screened out.21 strains of carbapenem antibiotics resistant to Enterobacter cloacae were performed the improved Hodge test and used to detect resistant genes of carbapenemase and hyperspectral β-lactamase(ESBLs)by using polymerase chain reaction(PCR)technique.The results of drug susceptibility tests were analyzed by WHONET 5.6 software.Results:The detection rates of Enterobacter cloacae in Gram-negative bacteria were 9.6%(317/3308),8.8%(218/2470),8.2%(174/2114)and 5.6%(157 / 2726)in 2013 to 2016,respectively.The results showed a downward trend.The main sources of the strains were sputum,wound secretions and secretions,and their constituent ratios were 48.3%(418/866),16.7%(145/866)and 11.0%(95/866),respectively.The strains were mainly distributed in the burns and respiratory sections,its constituent ratio was 17.7%(153/866)and 15.0%(130/866),respectively.The antimicrobial susceptibility tests showed that the drug resistance of Enterobacter cloacaeto ampicillin,cefoxitin and cefazolin were higher than 90%,amoxicillin / clavulanic acid and ampicillin / sulbactam higher than were 85%,piperacillin / tazobactam and cefoperazone / sulbactam were less than 30%,three generations of cephalosporins and quinolones antibiotic were less than 55%,aminoglycoside antibiotics was less than 35% and aztreonam was 38.1%.The resistance rate of carbapenem antibiotics is low.There were six strains with positive Hodge test results,the positive rate was 28.6%(6/21).The results showed that there were six strains with positive carbapenemase gene and the positive rate was 28.6%.There were one strain(4.8%)containing NDM-1 gene,four strains(19.0%)containing IMP gene,two strains(9.5%)containing KPC gene,and no VIM gene and SME gene were detected in the strains.Most of the resistant carbapenem-resistant Enterobacter cloacae were multidrug-resistant.The positive rate of ESBLs-producing strains was 38.1%(8/21).The positive rate of CTX-M gene was 9.5%(2/21).The positive rate of SHV gene was 9.5%(2/21).The positive rate of TEM gene was 19.0%(4/21).Conclusion:1.The detection rate of carbapenem-resistant Enterobacter cloacae was 2.4%,which required extensive attention from hospitals and clinicians.2.The drug resistance of Enterobacter cloacae to common antibiotics was downward trend,but the first-generation and second-generation cephalosporins antimicrobial agents showed a high resistant rate,but the third-generation and forth-generation of cephalosporins antibiotic had low resistant rate.3.Carbapenem-resistant Enterobacter cloacae contain a variety of drug resistance genes,the carbapenemase resistance genes and ESBLs resistance genes were more common.4.The ratio of IMP gene was the highest in carbapenemase resistance genes,and the highest proportion of TEM gene in ESBLs resistance genes.