Abstract: 【Objective】 The purpose of this study was to investigate the epidemiological and antibiotic resistance characteristics of Clostridium perfringens isolates from beef cattle in some areas of Inner Mongolia,and provide scientific basis for the prevention and treatment of Clostridium perfringens disease in beef cattle in these areas.【Method】 The tissue samples of 37 dead beef cattle were collected,and the bacteria were isolated and identified by isolation culture,staining microscopy and biochemical test.The toxin types and drug resistance genes of the isolated bacteria were detected by PCR,and the drug susceptibility test was conducted by K-B disk method.【Result】 The isolated bacteria appeared as black circular colonies on TSC medium and produced cloudy gas on TSA medium.Microscopic examination revealed short and thick Gram positive rods.The isolated bacteria fermented sucrose,glucose,maltose and hydrogen sulfide,causing gelatin to liquefy and undergo "burst" fermentation in an iron containing milk culture medium.Eight strains of Clostridium perfringens were isolated from the samples of 37 dead beef cattle,with an isolation rate of 21.62%.The PCR typing results of toxin genes showed that all the isolated strains only had cpa toxin and were type A Clostridium perfringens.The PCR detection results of resistance genes showed that multiple resistance genes were detected,with bla_TEM,tetM,ermB and sul2 genes having the highest detection rate of 100%.The detection rates of resistance genes aph(3')-Ⅲ-F,tetB(P) and ermC were 87.5%,62.5% and 62.5%,respectively,while the remaining resistance genes were not detected.The results of the drug sensitivity test showed that 8 strains of Clostridium perfringens were resistant to aminoglycoside drugs,with resistance rates of 100% for amikacin and streptomycin,and 87.5% for gentamicin and kanamycin.The resistance rates to compound sulfamethoxazole tetracycline and erythromycin were 100%,75.0% and 50.0%,respectively.And they were sensitive to ampicillin,cefazolin,chloramphenicol and clindamycin.【Conclusion】 There was a prevalence of Clostridium perfringens in cattle herds in some areas of Inner Mongolia,mainly type A,which had developed severe tolerance to antibiotics and multiple drug resistance.The experimental results could provide scientific basis for the epidemiological research,rational clinical drug use,and scientific prevention and control of Clostridium perfringens.

Key words: Clostridium perfringens; isolation and identification; drug resistance; drug resistance genes