The Analysis Of Related To Resistance Mechanisms In Acinetobacter Baumannii

Acinetobacter baumannii is an important conditional pathogenic bacteria resulting in the nosocomial infection, which can exist for a long time in the hospital environment, especially more relevant nosocomial infection appears in the people who are in the lower body resistance or impaired immune function. In the recent years, with broad-spectrum antimicrobial agents widely used, carbapenems-resistant Acinetobacter baumannii are increasing, and even full-resistant strains have emerged, which have brought new challenges to the clinical use of anti-infective drugs. At present, the integron as one of the important mechanisms which can generate and disseminate bacterial resistance has been the concern of many researchers, and more and more evidence indicated that integron has a close contact with the emergence and epidemic of multiple drug-resistant strains from the isolated clinical specimens. The aim of this topic is to analyse the integron characteristics and the trends of existence in Acinetobacter baumannii strains, and research the drug resistance mechanism which metallo-beta-lactamase (MBL) conducts the role of carbapenems resistance, so can provide the theoretical basis of choosing the reasonable antibiotics in the clinical cure.The subject using conventional laboratory methods is to isolate and identify 129 strains of Acinetobacter baumannii collected from clinical departments, with MIC and K-B methods combined to research the sensitivity of bacteria, and to understand the characteristics and distribution of bacterial resistance in the hospital.PCR was used to amplify the integrons and the variable regions with different primers, and to understand the distribution of integrons and integron-carried resistant gene box in Acinetobacter baumannii. 129 strains were detected and class 1 integron was found in 74 strains (57.4%) of clinical isolates and there were no class 2 or class 3 integron detected.Class 1 integron variable regions were found to carry the different gene cassettes where the majorities were the size of 2000bp,2500bp, 800bp and 350bp frangments, accounting for 61.2%and 32.8%. Five kinds of integron variable regions were identified by sequencing of the PCR product: dfrâ…¦dfrAl-orfC,aacA4-aadB,dfrA12-orfF-aadA2^ aacA4-catB8-aadAl.Phenotypic screening of metallo-beta-lactamase (MBL) was conducted in the 65 strains bacteria which were resistant to Imipenem or Meropenem by using Double-disk synergy test and Disc synergy test. The bacteria were detected by PCR amplification using different MBL gene (IMP-1, VIM-2, SIM-1) primers, and VIM-2 type was found, IMP-1 and SIM-1 type were not detected. MBL gene VIM-2 was confirmed by DNA sequencing and Genbank homology online comparative analysis.Class 1 integron-positive 65 strains were analyzed about clinical genotyping with the use of Enterobacterial Repetitive Intergenic Consensus Sequence PCR (ERIC-PCR) method. The analysis of gene homology can provide some basis to understand the distribution and the trends of the resistant bacteria in the hospital. The results showed that the detection of 65 strains can be divided into 20 different genotypes in which Clone A and Clone B are the prevalent strains.