犊牛传染性角膜结膜炎的病原菌分离鉴定及疗效观察

Isolation, identification and treatment of pathogens causing infectious keratoconjunctivitis in dairy calves

摘要

为明确河北省石家庄市某奶牛场犊牛传染性角膜结膜炎的致病菌并筛选高效防控药物，本研究采集发病犊牛眼拭子，经细菌分离培养、形态学观察、生化试验及16S rRNA基因序列分析鉴定致病菌；采用Kirby-Bauer纸片扩散法进行药敏试验，筛选优势药物，通过体外抗菌试验验证药物杀菌效果，结合临床治疗试验评估药物疗效。结果：分离的3株优势菌株均为牛眼莫拉氏菌（ Moraxella bovoculi）；分离菌株对恩诺沙星、头孢克肟等4种药物敏感，对青霉素、氨苄西林等3种药物耐药，其中恩诺沙星抗菌活性最强；聚六亚甲基双胍组与恩诺沙星组体外各时间点杀菌率均达100%，用药7 d后2组病牛眼部病变评分显著低于用药前，且无明显不良反应。综上，本研究分离鉴定出3株牛眼莫拉氏菌，为牛传染性角膜结膜炎防治提供参考。

Abstract

To identify the pathogenic bacteria causing infectious bovine keratoconjunctivitis in calves on a dairy farm in Shijiazhuang City, Hebei Province, and to screen for efficient prevention and control drugs, eye swabs were collected from the sick calves on the farm. The pathogenic bacteria were identified through bacterial isolation and culture, morphological observation, biochemical tests, and 16S rRNA gene sequence analysis. The Kirby-Bauer disk diffusion method was used to conduct antimicrobial susceptibility tests to screen dominant drugs, in vitro antibacterial tests were performed to verify the bactericidal effect of the drugs, and clinical treatment tests were carried out to evaluate the efficacy and safety of the drugs. The results showed that the 3 isolated dominant strains were all Moraxella bovoculi. The isolated strains were sensitive to 4 drugs, including enrofloxacin and cefixime, and were resistant to 3 drugs, including penicillin and ampicillin, among which enrofloxacin had the strongest antibacterial activity. The bactericidal rates of polyhexamethylene biguanide disinfectant and enrofloxacin reached 100% at all time points in vitro. After 7 days of treatment, the ocular lesion scores of the two groups were significantly lower than those before treatment, and no obvious adverse reactions were observed. This study isolated and identified 3 strains of M. bovoculi, providing a reference for prevention and treatment of infectious bovine keratoconjunctivitis caused by this bacterium.

关键词

牛眼莫拉氏菌 / 犊牛 / 牛传染性角膜结膜炎 / 药敏试验 / 体外抗菌 / 临床治疗

Key words

Moraxella bovoculi / calf / infectious bovine keratoconjunctivitis / antimicrobial susceptibility test / in vitro antibacterial activity / clinical treatment

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基金资助

国家重点研发计划项目(023YFD1301802)

中国农业科学院北方农牧业技术创新中心项目(BFGJ2023002)

河北省现代农业产业技术体系肉牛创新团队岗位专家项目(HBCT2024240201)