Lin Han, Sun Jingyang, Li Hua, Chen Kesong, Qin Zhendong, Jiang Biao, Li Wei, Wang Qing, Su Youlu, Lin Li, Liu Chun
Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, Innovative Institute of Animal Healthy Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province and Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China.
Vet Microbiol. 2025 Mar;302:110404. doi: 10.1016/j.vetmic.2025.110404. Epub 2025 Jan 20.
Acinetobacter johnsonii is a denitrifying bacterium commonly used as an environmental probiotic in wastewater treatment. However, research on its potential pathogenicity to animals is limited. During an epidemiological survey conducted from 2022 to 2024 at bullfrog farms in Guangdong Province, China, multiple strains were isolated from diseased bullfrogs during the low-temperature season. Three representative strains were selected for virulence testing, which showed high virulence to bullfrogs. Molecular identification confirmed these strains as A. johnsonii. One strain was named NW220314S and chosen for further study. Artificial infection through different routes revealed that the mortality rate of bullfrogs infected with this strain was higher at 15°C compared to 28°C. Additionally, the expression of at least 11 virulence genes was significantly higher at 15°C. Pathological examinations of bullfrogs infected with A. johnsonii showed systemic infection with extensive infiltration of inflammatory factors in organs, muscles, and skin. Immune-related gene expression analysis indicated a rapid and intense inflammatory response in bullfrogs post-infection. Our findings uncovered the novel phenomenon of the pathogenicity of A. johnsonii in bullfrogs under low-temperature conditions, warning of the potential threat of A. johnsonii to amphibian populations and the risks associated with its use in various environmental applications.
琼氏不动杆菌是一种反硝化细菌，常用于废水处理中的环境益生菌。然而，关于其对动物潜在致病性的研究有限。在中国广东省牛蛙养殖场于2022年至2024年进行的一项流行病学调查中，在低温季节从患病牛蛙中分离出多个菌株。选择了三个代表性菌株进行毒力测试，结果显示它们对牛蛙具有高毒力。分子鉴定证实这些菌株为琼氏不动杆菌。其中一个菌株被命名为NW220314S并被选作进一步研究。通过不同途径的人工感染表明，感染该菌株的牛蛙在15°C时的死亡率高于28°C时。此外，至少11个毒力基因在15°C时的表达显著更高。对感染琼氏不动杆菌的牛蛙进行的病理检查显示全身感染，器官、肌肉和皮肤中有大量炎症因子浸润。免疫相关基因表达分析表明牛蛙感染后有快速而强烈的炎症反应。我们的研究结果揭示了低温条件下琼氏不动杆菌在牛蛙中具有致病性的新现象，警示琼氏不动杆菌对两栖动物种群的潜在威胁以及其在各种环境应用中使用所带来的风险。
