革兰阴性杆菌ESBLs和AmpC酶的检测及耐药分析

Resistance surveillance of Gram negative bacilli producing ESBLs and AmpC enzyme

目的检测引起医院感染的革兰阴性杆菌携带产ESBLs和去阻遏AmpC酶状况,探讨各菌对临床常用抗生素的主要耐药机制及耐药性,为临床制定合理使用抗生素策略提供依据。方法采用全自动微生物分析仪(VITEK-32)做细菌鉴定和药敏试验,用纸片扩散确证法检测超广谱β-内酰胺酶(ESBLs),用三维法检测高水平表达染色体编码的AmpC酶。结果158株革兰阴性杆菌ESBLs检出率为26.6%,主要菌为大肠埃希菌(45.2%)、肺炎克雷伯菌(42.9%)、阴沟肠杆菌(11.9%)。AmpC酶检出率为10.1%,主要为鲍曼不动杆菌(43.8%)、阴沟肠杆菌(25%);上述产酶细菌均对青霉素和一、二、三代头孢菌素、磺胺类、喹诺酮类、氨基糖苷类耐药,对亚胺培南敏感。结论革兰阴性杆菌耐药机制主要是产超广谱β-内酰胺酶和AmpC酶,这些产酶菌株均出现多重耐药。

Objective To investigate the status of the drug resistance and the resistance of Gram negative clinical strains producing AmpC enzyme and ESBLs. Methods MICs of 13 different antimicrebial agents against 158 gram-negative clinical strains were determined by VITEK GNS card. The presence of ESBLs isolates were determined by the standard double-disk synergy test according to NCCLS. AmpC enzyme was detected by Cefoxitin in three dimensional test. Results 42 of 158 isolates were identified as being positive for ESBLs,the positive rate was 26.6%. E. coli,K pneumoniae and E. cloacae were 45.2% ,42.9% and 11.9% respectively. A total of 16 strains produced AmpC enzyme, accounting for 10. 1% ,which consisted mainly of Acinetobacter （43.8%） and E. cloacae （25%）. The resistance rate of AmpC enzyme and ESBLs producing strains to penicillins and the first- second- and third-generation eephalosporins sulfomides, fluoroquinolones and aminoglecosides were higher,which their resistance rate to imipenem were less. Conclusion The status of drug resistance of gram-negative clinical strains is severe. Detection of AmpC enzyme and ESBLs will be helpful in selection of the treatment of hospital infection.