肺炎克雷伯菌和大肠埃希菌AmpC β内酰胺酶的表型检测

目的 比较研究临床实验室对AmpCβ内酰胺酶（AmpC酶）的表型检测方法，了解对头孢西丁不敏感的肺炎克雷伯菌和大肠埃希菌中产生hmpC酶和超广谱β内酰胺酶（ESBLs）的分布情况。方法 利用加与不加3-氨基苯酚硼酸（APB）的头孢他啶、头孢噻肟和头孢西丁纸片进行APB纸片增强试验检测肺炎克雷伯菌和大肠埃希菌的AmpC酶，并与Tris-EDTA纸片试验检测AmpC酶的结果进行比较。用CLSI纸片确认实验检测肺炎克雷伯菌和大肠埃希菌产生的ESBLs。结果 APB纸片增强试验与Tris-EDTA纸片法检测结果完全一致。对头孢西丁不敏感的62株肺炎克雷伯菌和74株大肠埃希菌中，分别检测到产AmpC酶41株（66．1％）和33株（45．0％）。AmpC酶和ESBLs同时存在的肺炎克雷伯菌占51．6％，单产AmpC酶和单产ESBLs的肺炎克雷伯菌分别为14．5％和21．0％；而大肠埃希菌则以单产ESBLs为主，占40．5％，单产AmpC酶及同时产生AmpC酶与ESBLs的分别占20．3％和24．3％。结论 APB纸片增强试验和Tris-EDTA纸片试验操作简单，应用方便，成本低廉，均可用于临床实验室检测产AmpC酶的肺炎克雷伯菌和大肠埃希菌。

Detection for phenotype of AmpC beta-lactamase from Klebsiella pneumoniae and Escherichia coli

Objective To study the method for phenotype detection of AmpC beta-lactamase from Klebsiella pneumoniae and Escherichia coli,and to investigate the distribution of AmpC beta-lactamase and extended spectrum beta-lactamase (ESBL) in Klebsiella pneumoniae and Escherichia coli which were unsusceptible to cefoxitin.Methods AmpC beta-lactamase from Klebsiella pneumoniae and Escherichia coli were detected by 3-aminophenylboronic acid (APB) disk potentiation test in comparison with Tris-EDTA disk method. Ceftazidim,cefotaxim and cefoxitin with and without APB were used in the APB disk potentiation test.The disk confirmatory test for detection of ESBL approved by NCCLS was used for detection of ESBL.Results The APB disk potentiation test got good agreement with Tris-EDTA disk method. By detection using both methods 41 were AmpC beta-lactamase-producing in 62 strains of Klebsiella pneumoniae unsusceptible to cefoxtin (accounted for 66.1%) and 33 were AmpC beta-lactamase-producing in 74 strains of Escherichia coli unsusceptible to cefoxtin (accounted for 45.0%) .In Klebsiella pneumoniae,AmpC beta-lactamase with ESBL together was very common. AmpC beta-lactamase only,ESBL only and AmpC beta-lactamase with ESBL accounted for 4.5%,21.0% and 51.6% respectively.However, in Escherichia coli,ESBL only,ESBL with AmpC beta-lactamase,and AmpC beta-lactamase only accounted for 40.5%,24.3% and 20.3% respectively.Conclusion Both APB disk potentiation test and Tris-EDTA disk test were easy,convenient and cheap methods which could be applied for detection of AmpC beta-lactamase from Klebsiella pneumoniae and Escherichia coli in clinical laboratory.