亚胺培南对头孢他啶有诱导作用的铜绿假单胞菌耐药机制研究

目的研究本地区亚胺培南可诱导头孢他啶耐药的铜绿假单胞菌（Pa）发生率及金属酶基因、外膜通道蛋白OprD2基因存在情况及外排泵抑制剂与亚胺培南和头孢他啶敏感性之间的关系。方法收集临床分离的Pa325株,D试验筛选出116株亚胺培南可诱导头孢他啶耐药的Pa,纸片扩散法检测亚胺培南等14种抗菌药物的敏感性,采用PCR法检测IMP、VIM、SPM、GIM基因和外膜通道蛋白OprD2基因,琼脂稀释法测定该菌加入外排泵抑制剂羟基氰氯苯腙（CCCP）前后对亚胺培南和头孢他啶的MIC值。结果收集的325株Pa中,有35.7%（116/325）亚胺培南可诱导头孢他啶耐药,加入CCCP前后对亚胺培南和头孢他啶的敏感性无明显变化;116株Pa中,80.2%（93/116）是亚胺培南耐药而头孢他啶敏感,未检出IMP、VIM、SPM、GIM基因,87.1%（81/93）外膜通道蛋白OprD2基因缺失。结论铜绿假单胞菌中亚胺培南可诱导头孢他啶耐药,与其他耐药机制无关。外膜通道蛋白OprD2基因缺失是本地区Pa对亚胺培南耐药的重要机制。

Mechanism of imipenem induced ceftazidime resistance to pseudomonas aeruginosa

Objective： To investigate the incidence of imipenem induced ceftazidime resistance to pseudomonas aeruginosa（Pa）,the expression of βlactamase code gene and outer membrane channel protein OprD2 gene,and the relationship between inhibitor of efflux pump and the sensitivity of imipenem and ceftazidime.Methods：325 strains of Pa were collected and isolated from 5 regional hospitals.116 imipenem induced ceftazidime-resistance to Pa strains were isolated by D test.The sensitivity of 14 antibiotics including imipenem was tested by disc diffusion method.IMP,VIM,SPM,GIM genes and outer membrane channel protein OprD2 gene were tested by PCR.The MIC value of Pa to imipenem and ceftazidime were tested before and after efflux pump inhibitor CCCP was added.Results：Among the 325 strains of Pa,35.7%（116/325） showed imipenem induced ceftazidime resistance.The sensitivity to imipenem and ceftazidime had no change before and after CCCP was added.Among the 116 strains of Pa,80.2%（93/116） were resistant to imipenem while sensitive to ceftazidime,and no IMP,VIM,SPM,GIM genes were detected,with 87.1%（81/93） had gene deletion of the outer membrane channel protein OprD2.Conclusion： Pa can induce imipenem causing ceftazidime resistance with no other mechanisms involved.Disappearing of outer membrane channel protein OprD2 gene is an important mechanism of imipenem resistance in this area.