多药耐药鲍氏不动杆菌耐药基因检测与体外联合抗菌活性研究

Drug resistance genes in multidrug-resistant Acinetobacter baumannii and in vitro combination antimicrobial activity

目的调查医院多药耐药鲍氏不动杆菌(MDRAB)中耐药基因流行情况及体外联合抗菌效应,为临床治疗提供依据。方法采用聚合酶链反应法检测23株MDRAB中超广谱β-内酰胺酶(ESBLs)、头孢菌素酶(AmpC)和喹诺酮类相关耐药基因;琼脂倍比稀释法测定23株MDRAB对13种常用抗菌药物的最低抑菌浓度(MIC)及哌拉西林/他唑巴坦(TZP)、头孢哌酮/舒巴坦(CFS)和头孢吡肟(FEP)分别与阿米卡星(AMK)、环丙沙星(CIP)联合MIC,计算联合抑菌指数(FIC)。结果 23株鲍氏不动杆菌对13种常用抗菌药物全部耐药;联合体外抗菌活性显示,相加或协同的菌株分别为TZP+CIP占34.78%、FEP+CIP占34.78%、CFS+CIP占43.48%、TZP+AMK占95.65%、FEP+AMK占47.82%、CFS+AMK占65.22%;23株MDRAB中22株检出TEM型酶,6株检出SHV型酶,2株检出CTX-M型酶;8株检出AmpC酶,均为DHA型;aac(6′)-Ib阳性21株,qnrB基因阳性4株,gyrA基因阳性12株,parC基因阳性1株;其中2株检出6种耐药基因,3株检出5种耐药基因,4株检出4种耐药基因,5株检出3种耐药基因,8株检出2种耐药基因,1株检出1种耐药基因。结论医院MDRAB携带多种耐药基因;TZP、CFS联合AMK体外抗菌活性优于联合CIP。

OBJECTIVE To investigate the prevalence of drug resistance genes in multKlrug-resmtant iicznetooacter baumannii and study the in vitro combination antirnicrobial activity so as to provide guidance for the clinical treat- ment. METHODS The extended-spectrum beta-lactamase（ESBLs）,AmpC enzyme, and quinolones-resistant genes were tested in 23 strains of multidrug-resistant A. baumannii by using polymerase-chain-reaetion, then the mini- mum inhibitory concentrations （MICs） of the 23 strains of multidrug-resistant A. baumannii to 13 commonly used antibiotics were determined with the use of agar dilution method, and the MICs of piperacillin-tazobactam, cef- operazone-sulbactam, and cefepirne that were respectively combined with amikacin and ciprofloxacin were deter- mined, and the combined inhibition indexes were calculated. RESULTS All the 23 strains of A. baumannii were re- sistant to the 13 commonly used antibiotics. The combined in vitro antimicrobia[ activity indicated that the percent- ages of the strains with additive or synergistic antibacterial activity in antibiotics were 34.78% （piperacillin- tazobaetam plus eiprofloxacin, 34.78% （cefepime plus ciprofloxacin ）, 43.48% （cefoperazone-sulbactam plus cip- rofloxacin）, 95.65% （ piperaeillin-tazobactam plus smikacin）, 47.82% （cefepime-amikacin）, and 65. 220/40 （cef- operazone-sulbaetam plus arnikacin）, respectively. Of the 23 strains of multidrug-resistant A. baumannii, TEM was tested in 22 strains, SHV in 6 strains, CTX-M in 2 strains, AmpC in 8 strains, and all were the DHA type; aac（6＇）-Ib was tested positive in 21 strains, qnrB gene in 4 strains, gyrA gene in 12 strains, parC gene in 1 strain; 6 genotypes were tested in 2 strains, 4 genotypes in 4 strains, 3 genotypes in 5 strains, 2 genotypes in 8 strains, 1 genotype in 1 strain. CONCLUSION The multidrug-resistant A. baumannii strains carry multiple drug resistant genotypes. The in vitro antimicrobial activity of piperacillin-tazobactam or cefoperazone-sulbactam com- bined with amikacin is superior to that combined with ciprofloxacin.