Abstract: Haemophilus parasuis disease is a systemic infection of swine caused by Haemophilus parasuis. It mainly affects piglets at the nursery stage and is extremely harmful to pig farms. β-lactam drug is a kind of antibiotics used more clinically, and has the advantages of strong bactericidal activity, low toxicity, wide indications and good clinical curative effect, also often used to treat Haemophilus parasuis. To understand the drug resistance of Haemophilus parasuis to β-lactam antibiotics, and guide clinical drug use and new drug development more scientifically, this study referred to the method of establishing the epidemiological cut-off values in CLSI, to summarize the susceptibility results of strains from different regions to β-lactam drugs (determined by broth dilution method)， and to establish ECOFFs for β-lactam drugs. The ECOFFs of cefaclor，cefepime, cefotaxime, cefoquinme, ceftiofur, cefalexin, amoxicillin-clavulanic acid, amoxicillin, clavulanic acid, ampicillin, penicillin, oxacillin, imipenem and meropenem were recommended to be 16, 0.5, 0.125, 0.031 25, 0.5, 32， 0.25， 1， 0.5， 1， 2， 8， 0.25， 0.062 5 μg·mL^-1. In the absence of CLSI and EUCAST sensitivity criteria, the appearance of non-wild-type strains can be recognized directly, which is beneficial to the development of drug resistance monitoring and has certain reference value for the treatment and control of Haemophilus parasuis.

Key words: Haemophilus parasuis, β-lactam drugs, epidemiological cut-off values, drug-resistance