Résumé
Objectives To consider the reliability of using flucloxacillin (FCC) and clavulanic with extended spectrum cephalosporin synergy method (double inhibitors diffuse synergy test, DIDST) to detect AmpC ? lactamases (AmpC BLA) and extended spectrum ? lactamases (ESBLs). Method The FCC and clavulanic were regarded as the inhibitors of AmpC BLA and ESBLs respectively. The disks of ceftriaxone and cefepime were placed 20 mm away from the inhibitors, the disks of cefotaxime and the inhibitors were 25 mm apart. DIDST with a double disk synergy test, a cefoxitin three dimensional test, and a double disk enhancement test detected AmpC BLA and ESBLs in 56 strains of gram negative bacilli at the same time. Results 20 (35.71%) strains of ESBLs, 12 (21 43%) for AmpC BLA and 1 (1.78%) for ESBLs+AmpC BLA were found using DIDST, in 56 strains of G - B. During the double disk synergy test was used for ESBLs, 15 strains were found when the distance of the disks was within 25 mm, another 5 strains were found when the distance decreased to 20 mm. Twenty strains of ESBLs were found using the double disk enhancement test, and 12 strains of AmpC using the cefoxitin three dimensional test. The result of DIDST was similar to that of other three kinds of test. Conclusions DIDST is an accurate and reliable method using one plate to detect ESBLs and AmpC BLA of the same time. It is suitable for different levels of hospitals.