鲍氏不动杆菌对喹诺酮类抗菌药物的耐药性分析

Analysis of antimicrobial resistance of Acinetobacter baumanniito quinolones

目的分析临床分离的鲍氏不动杆菌对喹诺酮类抗菌药物的耐药特点及耐药机制。方法采用K-B纸片法测定33株鲍氏不动杆菌对喹诺酮类等21种抗菌药物的耐药性;用PCR技术扩增33株鲍氏不动杆菌的gyrA基因的耐药决定区,PCR产物经纯化后测序与GenBank中的标准序列比较,分析其突变情况。结果 33株鲍氏不动杆菌中,8株对环丙沙星耐药,占24.2%,4株对左氧氟沙星耐药占12.1%;对环丙沙星耐药的8个菌株均有gyrA基因突变,导致氨基酸变异为Ser-83→Leu,其中包括对左氧氟沙星耐药的4个菌株;所有对环丙沙星敏感的菌株未出现gyrA基因突变。结论 gyrA基因突变决定鲍氏不动杆菌对喹诺酮类抗菌药物的耐药。

OBJECTIVE To analyze the drug resistance characteristics and mechanisms to quinolones in 33 clinical isolates of Acinetobacter baumannii in Harbin. METHODS A total of 33 strains of A. baumannii were collected and their susceptibility to 21 antimicrobial agents was determined by K-B disk diffusion method. Quinolone resistance determining regions in gyrA gene were amplified by PCR and the PCR products were purified and sequenced, which were then compared with the standard sequences in the GenBank to analyze mutations. RESULTS The resistance rates of A. baumannii to ciprofloxacin and levofloxacin were 24.2 % （8/33） and 12.1% （4/33）, respectively. DNA sequencing showed that all the ciprofloxacin-resistant isolates had gyrA mutation （Ser-83→Leu in 8 strains）, which included the four isolates resistant to levofloxacin. No gyrA gene mutation was found in ciprofloxacin-susceptible strains. CONCLUSION Drug resistance of clinical isolates of A. baumannii to quinolones is determined by the mutation in gyrA.