颅脑外伤病人痰液中鲍曼不动杆菌gyrA基因突变与环丙沙星耐药关系研究

Relationship of the chromosomel gyrA gene mutation and ciprofloxacin resistance of Acinetobacter baumannii isolated from the sputum of patients with craniocerebral injury

目的了解分离自颅脑外伤病人痰液中鲍曼不动杆菌gyrA基因突变与环丙沙星耐药性的关系。方法用ATB药敏试验条板微量肉汤法测定27株鲍曼不动杆菌对14种抗菌药物的敏感性,采用聚合酶链反应(PCR)及序列分析的方法分析gyrA基因序列。结果27株菌中除HZ16号菌株对环丙沙星敏感外,其余26株均耐药。序列分析表明HZ16号菌株gyrA基因无突变,其序列已登录GenBank(accessionAY642140),其余26株耐药菌均存在gryA基因突变,导致耐喹诺酮决定区(QRDR)第83位的丝氨酸被亮氨酸取代。其中HZ28号菌株gyrA基因序列也已登录(GenBankAY642141)。结论gyrA基因突变是导致分离自颅脑外伤病人痰液中鲍曼不动杆菌对环丙沙星耐药的主要原因。

The susceptibility of 27 strains of Acenetobacter baumannii isolated from the sputum specimens of patients with craniocerebral injury to 14 antimicrobial agents was determined with micro-dilution testing, and the gene sequences of the chromosomal [WTBX]gyrA[WTBZ] gene from these bacterial strains were analyzed by PCR and verified by DNA sequencing. It was found that all these 27 strains of A.baumannii were resistant to ciprofloxacine except the HZ16 strain. The result of sequence analysis demonstrated that also except the HZ16 strain, all strains showed gyrA gene mutations, and the sequence data indicated that there was no mutation of gyrA gene, in HZ16 strain, whose data had been submitted to GenBank under a accession number of AY642140. The gyrA gene mutations of other 26 drug-resistant strains of A.baumannii led to the substitution of Ser-83 by leucine in quinolone-resistance determining region (QRDR). In addition, the sequence data of gyrA gene in HZ28 strain had also been submitted to GenBank with a accession number of AY642141. It is therefore, concluded that gyrA gene mutation is the main cause for the development of drug-resistance to ciprofloxacin in strains of A.baumannii isolated in sputum of patients with craniocerebral injury.