Study On The Class 1 Integrons Resistance And Biofilm Among Acinetobacter Baumannii

Objective:To understand the Acinetobacter baumannii strains present situation and levels of the drug resistance in Changsha,to provide the basis for the reasonable clinical application of the antibiotics;In order to study the mechanisms of class 1 integron drug resistance, Acinetobacter baumannii strains carrying class 1 integron were measured for the expression of class 1 integrase gene mRNA in the biofilm and planktonic cultured cells by semi-quantitative RT-PCR respectively.Methods:①The susceptibilities of 64 strains of clinical Acinetobacter baumannii to 8 kinds of antibiotic agents were tested by disc diffusion method.②All the clinical Acinetobacter baumannii class 1 integron positive strains were screened out by the gene amplification method.③Observation of biofilm growth and biofilm-forming ability were analyzed.④The class 1 integrase mRNA expression in bioflim cells and planktonic cultured cells were measured by RT-PCR methodResults:The isolates carried integrated gene-cassettes were commonly more resistant to the antibiotics than gene-cassettes negative isolates,which indicated integrated gene-cassette may be associate with antibiotic resistance in clinical Acinetobacter baumannii.②The class 1 integrons were found to be extensively existed in clinical isolates of Acinetobacter baumannii.46 strians carrying class 1 integrase were detected in 64strains isolates.9 strains carrying class 1 integrated gene-cassette were screened out by gene amplification in 46 strains.The amplification production concentrated between 1500bp to 3000bp.③Acinetobacter baumannii showed high biofilm-forming ability.42 isolates can form biofilm in 46 isolates.④Acinetobacter baumannii strains class 1 integrase mRNA expressed in their biofilm cells were higher than their planktonic cultured cells.The expression of intI1 in planktonic cell is 0.97±0.75,but the gene expression in biofilm is 2.54±0.67.Conclusion:The antibiotic resistance in Acinetobacter baumannii is very popular.The class 1 integron were found to be extensively existed in clinical isolates of Acinetobacter baumannii.The most strains showed biofilm-forming ability and the level expression of class 1 integrase gene was to be detected up-regulated in Acinetobacter baumannii biofilm cell.