Abstract: Objective To understand the current enzyme production and drug resistance of A.hydrophila forclinical treatment of A.hydrophila infection and to provide the basis for the rational use of antibiotics. Methods Fifty strains of A.hydrophilabacteria were collected from clinical specimens from 2011 to 2015.The routine drug sensitivity test was carried out using the K-B paper method,and the extended-spectrumβ-lactamases（ESBLs） was confirmed by the CLSI standard double disk tests.The AMPC was detected by three-dimensional test. Results Among 50 strains of A.hydrophila,15 strains produced ESBLs and 10 strains produced AMPC.All bacteria showed ampicillin resistance.Ampicillin/sulbactam resistant rate was 94%,and the third and the fourth generation cephalosporin resistant rate was 40% although the other antibiotics remained highly sensitive. Conclusion Clinical treatment of A.hydrophila infection should be careful with cephalosporins so as to improve the efficacy of antibiotics.

Key words: A.hydrophila, Antimicrobial sensitivity test, AmpC enzyme, Extended-spectrum β-lactamases