四联药敏纸片同步检测ESBLs和AmpCβ-内酰胺酶

Synchronous determination of ESBLs and AmpC beta-lactamases by four-disk test

目的建立一种简便、实用的方法,同步检测临床分离菌株的ESBLs和AmpCβ-内酰胺酶,为临床选择抗生素提供依据。方法用亚胺培南、阿莫西林/棒酸、头孢他定、头孢噻肟(或头孢曲松、氨曲南)四纸片琼脂扩散法,根据各纸片间抑菌的协同、拮抗作用及耐药谱判断结果。结果200株革兰阴性杆菌中有55株单产ESBLs(27.5%),33株诱导高产AmpC酶(16.5%),19株同时产ESBLs和诱导高产AmpC(9.5%),有20株去阻遏突变高产AmpC酶(10.0%)。四纸片同步法分别与双纸片增效法、头孢西丁三维试验比较,检测ESBLs、高产AmpC酶的总符合率分别为94.7%和93.6%。增加头孢曲松和氨曲南两种基质,ESBLs、诱导高产AmpC、ESBLs/诱导高产AmpC的检出率分别提高了16.3%、12.1%、15.8%。结论此方法不需任何特殊设备,能准确、简便、快速检测革兰阴性杆菌的ESBLs或AmpC酶,并能检测出同时携带两种酶的菌株。

Objective To establish a simple and practical method for screening ESBLs and induce AmpC beta-lactamases of gram negative bacillus at the same time and to instruct rational application of antibiotics clinically. Methods Beta-lactamases were determined by four-disk agar diffusion method with imipenem （IPM）, amoxicillin/clavulanic （AMC）, ceftazidime （CZA） and cefotaxime （CTX） for aztreonam （ATM）, ceftriaxone （CRO）]. Results In isolates of 200 gram negative bacillus, the detectable rates：ESBLs-producing strains was 27.5%; with 16.5% of induce AmpC-highly producing strains; 9.5% of producing ESBLs and induce AmpC strains; and 10.0% of mutational highly producing AmpC strains. Compared with double-disk synergy test and FOX three-dimensional test, the coincidence rates of four-disk synchronous test was 94.7% and 93.6% respectively. ATM and CRO were add, the positive rate of ESBLs-producing and induce AmpC-highly producing raise 16.3%, 12.1% and 15.8% respectively. Conclusion This method is simple, rapid and suitable for assay and differentiation of producing AmpC, ESBLs among gram negative bacillus, it is very important to select antibiotics correctly for infections of the patients.