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目的探讨中南大学湘雅二医院于2008-2009年临床分离到的不同基因型和耐药型的鲍曼不动杆菌的错配修复基因mutL的系统进化关系。方法以PCR扩增这一时期内5株分离自不同科室,具有不同基因型和耐药表型的鲍曼不动杆菌的错配修复基因mutL,运用软件ClustalX 1.83对mutL序列进行分析,基于该分析运用软件Mega 5.0采用邻接法(N-J法)构建系统进化树分析其系统进化关系。结果 (1)耐药型相同(对临床常用15种抗生素均耐药)的3株菌mutL序列完全一致,遗传距离为0.000;耐药型相似(对临床常用15种抗生素大多数敏感)的2株菌mutL序列相似度为98.95%,遗传距离为0.011,而与前3株的相对遗传距离大约分别为0.013和0.015;(2)序列分析显示这5株菌的mutL序列共发生了16个基因突变,其中有7个简约信息位点和9个自裔位点,这些突变导致了翻译过程中的12个错义突变、3个无义突变和2个同义突变。结论 (1)湘雅二医院2008-2009年发生过多重耐药鲍曼不动杆菌的院内交叉感染;(2)mutL序列中若干位点的基因突变会导致鲍曼不动杆菌耐药性变化,即错配修复基因mutL与鲍曼不动杆菌的耐药性状有关。
Objective To investigate the phylogenetic relationship of the mismatch repair gene mutL of different genotypes and resistant strains of Acinetobacter baumannii isolated from the Second Xiangya Hospital of Central South University from 2008 to 2009. Methods Five mismatch repair genes mutL from Acinetobacter baumannii isolated from different departments, different genotypes and drug resistance phenotypes were amplified by PCR. Mutl sequences were analyzed by software ClustalX 1.83. Analysis using software Mega 5.0 using adjacency method (NJ method) to build phylogenetic tree analysis of its phylogenetic relationship. Results (1) The mutL sequences of the three strains with the same drug resistance (resistance to 15 kinds of antibiotics commonly used in clinical practice) were identical and the genetic distance was 0.000. The resistance strains with similar drug resistance (sensitive to the most commonly used 15 kinds of antibiotics in clinical practice) The mutL sequence similarity of the strains was 98.95%, the genetic distance was 0.011, while the relative genetic distances to the first three strains were about 0.013 and 0.015, respectively. (2) The sequence analysis showed that there were altogether 16 genes Mutations, of which 7 parsimony informative sites and 9 self-loci, led to 12 missense mutations, 3 nonsense mutations and 2 synonymous mutations in translation. Conclusions (1) Cross-infection of Acinetobacter baumannii was observed in the Second Affiliated Hospital of Xiangya Hospital from 2008 to 2009; (2) The mutation of several sites in the mutL gene resulted in the change of drug resistance of Acinetobacter baumannii , The mismatch repair gene mutL and Acinetobacter baumannii resistant traits related.