鲍氏不动杆菌对喹诺酮类药物的耐药机制及菌株同源性分析

Mechanisms of quinolones resistance in Acinetobacter baumannii and homology analysis among the strains

目的探讨鲍氏不动杆菌对喹诺酮类药物耐药机制及菌株同源性分析。方法收集临床分离的喹诺酮类耐药鲍氏不动杆菌25株,采用纸片扩散法(K-B)检测其对常规药物的敏感性;采用聚合酶链反应(PCR)检测喹诺酮类耐药相关基因gyrA和parC基因,并经限制性内切酶酶切及测序方法验证;基因外重复回文序列(REP)-PCR分析菌株同源性。结果 25株鲍氏不动杆菌对12种抗菌药物呈现出多重耐药,仅对米诺环素和阿米卡星敏感,敏感率分别为48.0%和32.0%,对多黏菌素B全部敏感[最低抑菌浓度(MIC)≤2μg/mL];所有菌株检出gyrA和parC基因,25株菌株均存在gyrA基因第83位密码子TCA→TTA突变(Ser→Leu),23株菌株存在parC基因第80位密码子TCG→TTG突变(Ser→Leu),2株菌株存在parC基因第84位GAA→GGA突变(Glu→Gly);REP-PCR显示,所测菌株具有很高的同源性。结论耐喹诺酮类鲍氏不动杆菌具有很高的同源性,存在gyrA和parC基因突变位点。

Objective To explore the mechanisms of quinolones resistance in Acinetobacter baumannii and homology analysis a-mong the strains .Methods 25 strains of quinolones-resistant Acinetobacter baumannii isolated clinically were collected .Kirby-Bauer（K-B） detection was utilized to detect the sensitivity of conventional drugs ,and polymerase chain reaction （PCR） was em-ployed to detect quinolone resistance-related genes gyrA and parC which were verified by restriction enzyme digestion and sequen-cing ,repetitive extragenic palindrome（REP）-PCR was adopted to analyze the strain homology .Results Multiple resistances to 12 kinds of antibacterial agents were found among the 25 strains of Acinetobacter baumannii which were sensitive only to minocycline and amikacin ,with sensitive rates were 48 .0% and 32 .0% ,respectively ,and were all sensitive to polymyxin B [minimal inhibitory concentration（MIC）≤2 μg/mL] .gyrA and parC genes were found in the all strain .Mutation TCA→TTA（Ser→Leu） at coden 83 in gyrA gene existed in 25 strains ,mutation TCG→TTG（Ser→Leu） at coden 80 in parC gene existed in 23 strains ,mutation GAA→GGA（Glu→Gly） at coden 84 in parC gene existed in 2 strains .REP-PCR showed that the strains had high degree of homology . Conclusion Quinolone-resistant Acinetobacter baumannii has high degree of homology ,existing gyrA and parC gene mutations .