Abstract: 【Objective】 The purpose of this experiment was to isolate and identify Salmonella from goat,detect its resistance to common antibacterial drugs and the bacteriostati effect of Chinese herbal medicines,aiming to provide a reference basis for the prevention and treatment of Salmonella-related diseases. 【Method】 A total of 33 anal swab samples and 17 nasal swab samples of Leizhou goats with symptoms of diarrhea and rhinorrhea were collected from a goat farm in Zhanjiang city,and bacterial isolation and purification were carried out.The pathogenic bacteria were identified by Gram staining,PCR amplification and sequencing.The minimum inhibitory concentration (MIC) of 15 commonly used antibacterial drugs against the isolated strains was determined by microbroth dilution method.The sensitivity of the isolates to 12 kinds of Chinese herbal medicines was determined by the double dilution method in test tubes.Subsequently,the in vitro bacteriostati effect of the combined application of different Chinese herbal medicines on the isolates was further explored.The biofilm formation amount of the isolates was determined by crystal violet staining. 【Result】 The isolated bacteria presented as round,neatly edged,slightly raised,colorless and transparent single colonies on Maclonkey agar medium.White,round and neatly edged single colonies appeared in the nutrient agar.Gram staining showed Gram-negative bacilli with blunt and round ends,no spores and no capsules.The PCR amplification results of 16S rRNA gene showed that a band with a fragment size of 1 500 bp.BLAST comparison results showed that the similarity between the isolated strains and Salmonella Enteritis (accession number:AE016841) was more than 97%.A total of 15 goat-derived Salmonella were isolated from 50 collected samples,with an isolation rate of 30%.The results of the drug susceptibility test showed that the resistance rates of the isolates to penicillin and ceftazidime were 90% and 70% respectively,the resistance rates to azithromycin and sulfadiazine sodium were both 40%,and the resistance rates to cefazolin sodium,oxytetracycline,streptomycin and acetoquinine were all 10%.The isolated strains were sensitive to amikacin,doxycycline,kanamycin,sulfamonomethoxil,piperacillin,minocythromycin and enrofloxacin.The results of the antibacterial test of Chinese herbal medicines showed that the MIC of Prunus mume and Schisandra chinensis against the isolates was 15.62 mg/mL,and the MIC of Coptis chinensis against the isolates was 62.5 mg/mL.The results of the combined medication test of Chinese herbal medicines showed that the MIC of the Chinese herbal medicine compound prescriptions composed of Coptis chinensis＋Atractylodes lancea,Schisandra chinensis＋Terminalia chebula,and Schisandra chinensis＋Pogosteom cablin was 15.62,7.81 and 7.81 mg/mL respectively.The results of growth curve and biofilm detection showed that the 2MIC Coptis chinensis,Prunus mume and Schisandra chinensis had the good antibacterial effect,among which Schisandra chinensis had the best effect in inhibiting the formation of Salmonella biofilms. 【Conclusion】 In this study,15 goat-derived Salmonella were isolated and obtained.The extracts of Chinese herbal medicines had a significant in vitro antibacterial effect,and when some Chinese herbal medicines were used in combination,the antibacterial activity could be enhanced.This results had significant guiding significance for Chinese herbal medicine in the prevention and treatment of Salmonella infections,and also provided data support for further exploration of comprehensive prevention and treatment strategies for Salmonella diseases in the future.

Key words: goat; Salmonella; drug resistance; Chinese herbal medicine; bacteriostati effect