产ESBLs及AmpC酶细菌检测方法的探讨

目的 比较双纸片抑制协同法(DDIST)、纸片扩散法与三维试验法检测临床分离革兰阴性肠杆菌产ESBLs及AmpC酶的可靠性。方法 用纸片扩散法从临床分离株中初筛出88株产ESBLs与AmpC可疑菌株，再用DDIST和三维试验进行比较。结果 纸片扩散法检出产ESBLs菌77株，可疑产AmpC菌6株，另有5株为不确定产酶株。DDIST检出产ESBLs菌77株(87．5％)，产AmpC菌10株(11．4％)(包括纸片中心距离20mm的9株、15mm的1株)，产ESBLs AmpC菌1株(1．1％)。三维试验检出AmpC11株，ESBLs78株。DDIST，三维试验总符合率达到100％。结论 DDIST可同时检测产ESBLs和AmpC的细菌，方法准确简便，适于各级临床实验室应用。

Study on methodology of detection for extended-spectrum beta-lactamase and AmpC

Objective To compare the reliability of three methods:(double disc inhibitory synergy test, disk diffusion test and three dimensional test) in the detection for extended spectrum beta lactamase (ESBLs) and plasmid encoded AmpC produced by clinically isolated gram negative bacilli.Methods Eighty eight strains producing ESBLs were clinically isolated by disk diffusion screen test,and were subsequently detected by double disc inhibitory synergy test (DDIST) and cefoxitin three dimensional test.Results By DDIST the ESBLs ,AmpC and ESBLs+AmpC producing strains were 77 (87.5%), 10(11.4%) and 1(1.1%) respectively.Of 10 AmpC producing strains,9 strains were found within 20 mm of the distance of disk,another strains was found when the disk distance was decreased to 15 mm.By disc diffusion test the ESBLs producing ,suspicious AmpC producing and undefinable strains were 77,6 and 5,respectively.By cefoxitin three dimensional test the ESBLs and AmpC producing strains were 78 and 11 respectively.The results of DDIST was similar to those of cefoxitin three dimensional test.Conclusions DDIST is an accurate and reliable method for detection of ESBLs and AmpC simataneously by using one plate,and suitable for the clinical laboratories with different scale.