China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (8): 3275-3285.doi: 10.16431/j.cnki.1671-7236.2023.08.025

• Preventive Veterinary Medicine • Previous Articles    

Isolation,Identification and Biological Characteristics Analysis of a Moraxella pluranimalium Strain from Tibetan Pigs

MA Jing1, YANG Danjiao2, WEI Longpin1, GAN Daibing1, LONG Zhixin1, HE Yuqi1, QING Ting1, FAN Yandi1, ZHOU Long1   

  1. 1. School of Animal Husbandry and Veterinary Medicine, Southwest Minzu University, Chengdu 610041, China;
    2. Institute of Animal Husbandry Science, Ganzi Tibetan Autonomous Prefecture, Sichuan Province, Kangding 626000, China
  • Revised:2023-04-29 Published:2023-07-27

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Abstract: 【Objective】 This study was aimed to determine the pathogenic bacteria of Tibetan pigs in Ganzi Tibetan Autonomous Prefecture of Sichuan province,explore the genetic relationship and drug resistance among the strains,and provide scientific basis for effective prevention and control.【Method】 A suspicious pathogenic bacteria was isolated from lung of dead pig.The isolated strains were identified and analyzed by bacterial isolation and culture,16S rRNA PCR amplification and sequencing,genetic evolution analysis,drug sensitivity test,drug resistance gene and 23S rRNA mutation site detection,biofilm test and pathogenicity test of mice,respectively.【Result】 The results of 16S rRNA PCR amplification and genetic evolution analysis showed that the nucleotide sequence similarity between this strain and Spanish strain CR-18,LG6-7g,AR-5A and GM5-1 was 100%,respectively,and it was clustered into a genetic branch with Moraxella suis,indicating that this pathogen was Moraxella pluranimalium,named KD-4.Morphological observation result showed that this strain was a Gram negative diplococcus of kidney type.The biofilm test determined that the bacteria could form biofilm,so that the bacteria still colonized in the body after the animal disease healed,and became the host of the pathogen for a long time.The results of drug sensitivity test showed that this strain was highly sensitive to the antibiotics Fudaxin and sulfaisoxazole;Moderately sensitive to spectinomycin hydrochloride and meropenem;Resistant to ampicillin,gentamicin,amoxicillin,cefotaxifur sodium,florfenicol,tetracycline and enrofloxacin.Among them,the minimum inhibitory concentration (MIC) of Fudaxin,sulfaisoxazole,spectinomycin hydrochloride and meropenem against this bacterium were 2,128,64 and 2 μg/mL,respectively.The results of drug resistance gene detection showed that ermF,ermB,tetB,tetD,blaTEM and blaCTX-M genes were not detected.23S rRNA sequence analysis results showed that there were 15 mutation sites such as A2982T and C3132T,which might be related to the multiple drug resistance of the isolated strain.The pathogenicity test of mice showed that the bacteria could cause a small amount of bleeding spots in lung of mice,and the spleen was obviously swollen,but it was not fatal,and it could recover health after tolerance.【Conclusion】 This study was the first report of Moraxella pluranimalium from Tibetan pigs in China,and the results of drug sensitivity test could provide reference basis for disease prevention and epidemiological investigation caused by this bacterium.

Key words: Tibetan pigs; Moraxella pluranimalium; isolation and identification; drug susceptibility test; pathogenicity

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