一株耐碳青霉烯阴沟肠杆菌金属β-内酰胺酶的检测

Detection of Metallo β-lactamase in a Strain of Carbapenem resistance Enterobacter Cloacae

目的初步探究一株耐碳青霉烯阴沟肠杆菌的耐药机制。方法采用K-B法检测该菌株对碳青霉烯类及其他常用抗菌药物的耐药性,采用改良Hodge实验和EDTA双纸片协同试验对碳青霉烯酶进行初筛,并用4对金属酶基因引物进行PCR扩增,同时进行AmpC酶的检测。结果药敏试验显示,该菌株对碳青霉烯和三代头孢耐药,并不被传统β-内酰胺酶抑制剂所抑制(对阿莫西林-克拉维酸和头孢哌酮-舒巴坦耐药),但对单环类的氨曲南敏感。改良Hodge试验和组合纸片法金属酶的初筛试验均为阳性,PCR检测结果显示该菌株携带Vim-2及Vim-5型金属酶基因。AmpC酶检测结果表明受试菌产诱导型AmpC酶。结论产Vim-2和Vim-5型金属酶是此株阴沟肠杆菌对碳青霉烯类耐药的重要原因,产诱导型AmpC酶可能参与其多重耐药机制,同时提示碳青霉烯类耐药性有向肠杆菌科扩散的趋势。

Objective To detect the carbopenems resistance mechanisms of a strain of Enterobacter cloacae preliminary. Methods The carbopenems and other antibiotics resistance of the Enterobacter cloacae were studied by using Kirby- Bauer method, the carbapenemases were screened with a modified Hodge method and EDTA double- disk synergy test, and then the PCR amplification was carried out with 4 pairs of metal gene primers, the AmpC enzyme was tested at the same time. Results The drug sensitive test showed that the strain we studied was resistant to carbapenems and three generation cephalosporin, and it was not inhibited by conventional beta- lactase inhibitors （amoxycillin- clavulanic acid and cefoperazone- sulbactam drug resistant ）, but it was sensitive to the monocyclic aminotram. The results of the modified Hodge method and EDTA double - disk synergy test were all positive. The PCR test indicated that the Enterobacter cloacae carried vim- 2 and vim- 5 metalloenzyme genes. The AmpC test showed that the strain induced AmpC enzyme. Conclusion The vim- 2 and vim- 5 metalloenzyme are important factors for the strain of carbopenem resistance Enterobacter cloacae, the induced AmpC enzyme may be involved in its multidrug- resistant mechanism, the results also indicate that there is a tendency for earbapenems resistance to spread to enterobacteriaceae.