目的 了解鲍曼不动杆菌对喹诺酮类抗菌药物的常见耐药性及其机制,为临床抗感染治疗提供依据,以指导临床合理用药.方法 采用VITEK系统鉴定细菌,用M-H琼脂定量稀释法测定菌株对左氧氟沙星、环丙沙星和加替沙星3种喹诺酮类药物的最低抑菌(MIC),PCR扩增gyrA和parC基因,选取部分PCR扩增产物进行测序分析.结果 临床标本共检出120株鲍曼不动杆菌,中心重症监护室、呼吸科病房、急救中心分离菌所占比率分别为28.3%、24.2%、12.5%;对环丙沙星、左氧氟沙星和加替沙星的耐药率分别为78.3%、58.3%和40.0%.PCR基因扩增和测序结果:所有菌株均扩增出了相应gyrA和parC基因产物;耐药株中的gyrA基因存在83位氨基酸密码子突变,敏感株中则不存在该突变,并在耐药株中发现gyrA和parC基因针对GenBank号分别为DQ270238和EU977576的菌株存在新的点突变.结论 鲍曼不动杆菌对喹诺酮类药物耐药情况严重,其耐药性与gyrA和parC基因点突变有关.%Objective To investigate the distribution and drug resistance of Acinetobacter baumanii strains isolated in our hospital, to examine the genetic mechanisms of resistance by molecular methods and to provide evidence for the clinical therapy of infections. Methods Microorganisms were identified by VITEK system, minimum inhibitory concentration(MICs) of levofloxaein, ciprofloxacin and gatifloxacin were determined by using agar dilution method.Genes gyrA and parC were amplified by polymerase chain reaction (PCR), and some PCR products were sequenced. Results A total of 120 strains of Acinetobacter baumanii species were collected, the percentage of isolated bacteria in intensive care unit, respiratory department and emergency center was 28.3％ ,24. 2％, 12. 5％ respectively. The resistance rate of Acinetobacter baumanii isolates to ciprofloxacin, levofloxacin and gatifloxacin was 78.3％ ,58.3％ and 40. 0％ respectively. PCR and DNA sequencing indicated that all strains of Acinetobacter baumanii had PCR products of gyrA and parC genes, there were the point mutations in gyrA genes at codon 83 of quinolones resistant strains but no such mutation in sensitive strains. We found the new point mutations in gyrA and parC genes of resistant strains which the Genbank number was DQ270238 and EU977576, respectively. Conclusion The current status of resistance to quinolones with Acinetobater baumannii is serious, and the resistance is related to the point mutations with gyrA and parC genes.
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