多重耐药阴沟肠杆菌质粒型AmpC酶DHA-1基因的检出

Detection of plasmid type AmpC lactamase DHA gene in multidrug resistant Entero-bacter cloacae

目的测定56株同时耐头孢噻肟、庆大霉素和环丙沙星的阴沟肠杆菌质粒型AmpC酶基因型。方法先后用头孢西丁纸片法、三维试验、等电聚焦及酶抑制试验和微量稀释法进行表型检测。接合试验证实酶基因的转移性。多重聚合酶链反应以及基因测序等方法鉴定质粒型AmpC酶基因型。结果受试的56株细菌中有5株三维试验阳性,其中1株能转移接合,接合子多重聚合酶链反应扩增结果呈阳性,等电点为7.8,基因测序表明和DHA-1型AmpC酶一致。结论我国的多重耐药阴沟肠杆菌已获得质粒型DHA基因,DHA基因可通过转化、接合等方式转移给其他细菌且易于传播,因此应加强监控以防DHA基因在革兰阴性菌中流行。

Objective To analyze plasmid type AmpC β-1actamase DHA gene in 56 strains of Enterobacter cloacae simuhaneously resistant to cafotaxime, gentamicin and ciprofloxacin. Methods The clinical isolates of Enterobacter cloacae were examined by standard disk difusion susceptibility tests,three-dimensional methods,isoelectric focusing and microdilution methods. Conjugation experiment was used to study the transfer of resistance. Multiplex PCR and DNA sequencing methods were used for further analysis. Results Five out of a total of 56 isolates tested were shown to be highly AmpC-producing by three-dimensional method. Only one transferred resistance to cefoxitin. IEF showed that this strain produced a AmpC like lactamase with a isoelectric point of 7.8, and DNA sequencing showed that the gone which expressed this AmpC like lactamase was identical to DHA-1, a plasmid mediated cephalosporinase gone. Conclusions The Enterobacter cloacae strains simuhaneously resistant to cafotaxime,gentamicin and ciprofloxacin have gained DHA gone in our country,plasmid type AmpC β-1actamase DHA gone can be transferred in bacteria by transforming or integrating and easy to be transferred, the intensive attention should be paid to avoid DHA gone being prevalent in Gram-negative bacteria.