鲍氏不动杆菌染色质ampD基因的研究

Exploration Investigation of Genomic ampD from Acinetobacter baumannii

目的了解鲍氏不动杆菌染色质ampD基因及其高概率突变位点。方法从医院感染患者临床标本中分离鲍氏不动杆菌,经头孢西丁初筛试验和头孢西丁三维试验确定是否产AmpCβ-内酰胺酶及其产酶类型,抽提产酶菌株染色质DNA,PCR法扩增ampD基因并连接入pMD19-T载体,双链测序后与同种非突变标准菌株的ampD基因序列比对,并得到高概率突变位点。结果大部分产酶的鲍氏不动杆菌含有ampD基因,其中18株产持续高酶菌株的染色质中均扩增出ampD基因;鲍氏不动杆菌ampD基因上有62个突变率>50%的位点。结论产AmpCβ-内酰胺酶的鲍氏不动杆菌染色质上均含有ampD基因;鲍氏不动杆菌染色质ampD基因的高概率突变位点可能成为致持续高产酶的关键位点。

OBJECTIVE To explore the genomic ampD and its mutation sites with high probability from Acinetobacter baumannii.METHODS The strains of A.baumannii were isolated from the nosocomial infectious patients in our hospital.The ability and the types of producing AmpC β-lactamases were comfirmed by the improved Cefotaxime three-dimensional test.The gennomic DNA was extracted,genomic ampD was amplified by using PCR,ligated into pMD19-T vector,and sequenced.Mutation mMutation sites were analyzed by comparing with the AmpD sequence of the standard wild-type strains.RESULTS Most parts of the strains contained the genomic ampD.Among them,genomic ampD was amplified in all the clinical isolates Iisolates producing durative high expressed AmpC β-lactamases.The sequences of ampD were successfully obtained;A.baumannii contained 62 mutation sites with the mutation rate over 50%.CONCLUSION All the strains of A.baumannii producing durative high expressed AmpC β-lactamases contain genomic ampD;the mutation sites with high probability maybe the potential cause of producing durative high expressed AmpC β-lactamases.