| Objective: To study on the detecting methods of induction and high-level producing AmpC β-lactamases in Enterobacter, and evaluate the feasibility of their application in the clinical laboratory. To investigate the expression of high induction and high-level producing AmpC β-lactamases among clinical isolates of Enterobacter and its impact on antibiotic susceptibility, and provide objective evidences to rational use of antibiotics. Methods: We collected 121 of clinical isolates of Enterobacter, including 87 isolates Enterobacter cloacae, 34 isolates Enterobacter aerogenes, all of the isolates were detected by cefoxitin three-dimension test, drug resistance phenotypes estimation, cloxacillin disc synergy test and cloxacillin-potentiated disc diffusion test respectively to find high-level AmpC β-lactamase isolates, drug resistance phenotypes estimation were also used to detected high induction producing AmpC β-lactamases isolates, meanwhile, we took three-dimension test as standard method, and compared to other methods, then calculated the coincidence rates, sensitivities and specificities of them. Then Trace Broth Dilution Method was adopted to detect MICs of 20 different antibiotics used frequently, and we analysed drug-resistance of those high induction and high-level producing AmpC β-lactamases strains according to NCCLS standards. Results: 1. Among 121 clinical isolates of Enterobacter, 28 isolates were considered as high-level producing AmpC β-lactamases strains, including 23 isolates Enterobacter cloacae and 5 isolates Enterobacter aerogenes, the total detection rate was 23.1%. 2. According to resistance or intermediate to FOX, we prescreened 98 high-level producing AmpC β-lactamases isolates, positive rate was 81.0%; 86 high induction producing AmpC β-lactamases isolates were found with drug resistance phenotypes estimation, the total detection rate was 71.1%. 3. By comparison to cefoxitin three-dimension test in detecting high-level producing AmpC β-lactamases isolates, the...
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