革兰阴性杆菌中AmpCβ-内酰胺酶的检测及其耐药性分析

Detection of AmpC β-lactamases and analysis of its drug resistance in gram-negative bacilli

目的了解革兰阴性杆菌临床分离株AmpCβ-内酰胺酶的发生率及产酶株的耐药性。方法采用三维试验检测AmpCβ-内酰胺酶;用K-B纸片法进行抗菌药物敏感试验。结果236株革兰阴性杆菌中,三维试验阳性菌株29株;17株(7.2%)单产AmpC酶,8株(3.4%)单产超广谱β-内酰胺酶(ESBLs),2株(0.8%)同时产AmpC酶和ESBLs,2株(0.8%)为非产AmpC酶和ESBLs菌株;共检出产AmpC酶菌株19株,检出率为8.1%;药物敏感试验结果显示,除亚胺培南和头孢吡肟外,产酶株的耐药率明显高于非产酶株。结论本院革兰阴性杆菌AmpC酶的检出率为8.1%;产酶菌呈多重耐药特性,治疗产酶菌感染首选第四代头孢菌素及碳青霉烯类药物。

Objective To investigate the incidence of clinical isolates of gram-negative bacilli producing AmpC β- lactamases and its drug resistance. Methods AmpC β-lactamases were identified by three-dimensional test; and the susceptibilities of antimicrobial agents were detected by Kirby-Bauer disk diffusion test. Results Of 236 gram-negative bacilli,29 strains produced β-lactamases with three-dimensional test, 17 strains （7.2%） only had AmpC β-lactamases, 8 strains （3.4%） only had extended-spectrum beta-lactamasea （ESBLs）, 2 strains （0.8%） had both ESBLs and AmpC,2 strains （0.8%） had no AmpC-ESBLs β-lactamases. Therefore, 19 strains produced AmpC β-lactamases, the frequency of AmpC β-lactamases was 8. 1%. The susceptibility test showed that the drug resistant rate of AmpC producer was higher than non-AmpC producer except imipenem and cefepime. Conclusion The frequency of AmpC β- lactamases was 8.1% in the hospital. Multiple drug resistance appeared in AmpC producer. The fourth-generation cephalosporins and carbapenems should be considered to treat the infection caused by AmpC producer at first.