China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (2): 745-753.doi: 10.16431/j.cnki.1671-7236.2023.02.032

• Basic Veterinary Medicine • Previous Articles     Next Articles

Isolation,Identification and Drug Resistance Analysis of Streptococcus from Yak

WANG Bingyi1, MA Hongcai2,3, ZOU Minghao1, FAN Shijie1, YUAN Zhenjie2,3, Labaciren4, DONG Hailong1, ZENG Jiangyong2,3   

  1. 1. College of Animal Science, Tibet Agriculture and Animal Husbandry College, Nyingchi 860000, China;
    2. Tibet Livestock Research Institute, Tibet Academy of Agricultural and Animal Husbandry Sciences, Lhasa 850009, China;
    3. State Key Laboratory of Hulless Barley and Yak Germplasm Resources and Genetic Improvement, Lhasa 850009, China;
    4. Animal Husbandry and Veterinary Station of Lhasa, Lhasa 850000, China
  • Received:2022-08-10 Online:2023-02-05 Published:2023-02-06

Abstract: 【Objective】 This study was aimed to understand the infection,pathogenicity and drug resistance of Streptococcus from yak in Lhasa,Tibet,and provide new data for the study of Streptococcus from yak.【Method】 Bacterial isolation and culture,colony morphology observation,microscopic examination with Gram staining,biochemical identification and 16S rRNA sequence PCR amplification were performed on 55 yak nose swabs to identify the species characteristics of the isolates.The pathogenicity of the isolated bacteria was evaluated by the artificial infection test in mice.Finally,the drug resistance of the isolated bacteria was detected by disk diffusion method.【Result】 The isolated bacteria grew gray-white,smooth α-hemolytic round colonies on the blood plate,and Gram staining microscopic examination showed chain-like positive cocci. The isolated bacteria could ferment glucose, lactose, trehalose and sorbitol, but could not ferment maltose and glycerol. The nitrate reduction test, indigo substrate test, V-P test and MR test were negative. 16S rRNA gene sequence alignment analysis showed that,25 strains of Streptococcus (Tibet-1 to Tibet-25) were identified,and the detection rate was 45.46% (25/55),including 17 strains of Streptococcus pluranimalium and 8 strains of Streptococcus equi.The similarity between the 16S rRNA gene sequence of isolated bacteria and the Streptococci published on NCBI was 97.04%-99.77%.Among them,11 strains of Streptococcus pluranimalium from yaks,including Tibet-1,Tibet-2,Tibet-3,Tibet-5,Tibet-9,Tibet-10,Tibet-11,Tibet-14,Tibet15,Tibet-16 and Tibet-17,had more than 99% similarity with KM981770.1.The isolated Streptococcus from yak could cause diarrhea in mice. Streptococcus could be isolated from the organs of infected mice by enrichment culture.The results of drug sensitivity test showed that the isolated strains were highly sensitive to 11 antibiotics,including doxycycline,erythromycin,penicillin,and so on.It was highly resistant to compound sulfamethoxazole.【Conclusion】 This study isolated Streptococcus pluranimalium and Streptococcus equi from yak,and analyzed their pathogenicity and drug resistance,which provided a reference basis for the prevention,control and treatment of the disease.

Key words: yak; Streptococcus pluranimalium; Streptococcus equis; isolation and identification; drug resistance

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