猪源豚鼠气单胞菌的生物学特性

Biological characterization of swine-derived Aeromonas caviae

摘要:

【背景】 豚鼠气单胞菌(Aeromonas caviae)是一种分布广泛，可以导致人和多种动物致病的病原菌，对食品安全和公共卫生造成巨大潜在威胁。【目的】 了解猪源豚鼠气单胞菌的致病特征及耐药谱，为临床防控提供理论依据。【方法】 从河南某猪场病死仔猪内脏中分离获得优势菌株HNHB，通过形态学观察、基质辅助激光解吸电离飞行时间质谱(matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry, MALDI-TOF MS)及16S rRNA基因系统发育树构建进行菌种鉴定。采用昆明鼠感染模型评估其致病性(LD₅₀测定及组织病理学分析)，并对分离菌株进行14种抗菌药物的最小抑菌浓度(minimal inhibitory concentration, MIC)检测。【结果】 分离菌株HNHB经多相分类学鉴定为豚鼠气单胞菌，其16S rRNA基因序列与豚鼠气单胞菌(GenBank登录号为AP026375)相似度为99.73%。小鼠感染试验显示，菌株HNHB对昆明鼠的LD₅₀为6.24×10⁸ CFU/mL，可引发昆明鼠肠道组织坏死、出血及上皮细胞脱落，肝脏和肾脏肿大等病变。药物敏感性试验表明，该菌株对头孢他啶(MIC=0.32 μg/mL)、多黏菌素(MIC=0.01 μg/mL)等5种药物高度敏感，但对氟苯尼考(MIC=128 μg/mL)、美罗培南(MIC=160 μg/mL)等呈多重耐药性。【结论】 从病死猪内脏器官成功分离鉴定1株豚鼠气单胞菌HNHB，该菌株对昆明鼠有致病性，并呈现多重耐药性。

Abstract:

[Background] Aeromonas caviae is a widely distributed pathogen capable of infecting both humans and multiple animal species, posing significant threats to food safety and public health. [Objective] To investigate the pathogenic characteristics and antimicrobial resistance profile of swine-derived A. caviae, providing theoretical guidance for clinical prevention and control. [Methods] A dominant strain (designated HNHB) was isolated from the viscera of deceased piglets in a swine farm in Henan Province. The strain was identified by morphological observation, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and phylogenetic analysis based on the 16S rRNA gene. A Kunming mouse infection model was established to evaluate the pathogenicity of this strain based on the LD₅₀ value and histopathological changes, and the minimal inhibitory concentrations (MICs) of 14 antimicrobial agents against this strain were determined. [Results] The isolate HNHB was identified as A. caviae, with the 16S rRNA gene sequence similarity of 99.73% compared with the reference A. caviae strain (GenBank accession number: AP026375). Infection trials revealed the LD₅₀ of 6.24×10⁸ CFU/mL in Kunming mice. HNHB induced severe multiorgan lesions, including intestinal necrosis, hemorrhage, epithelial shedding, hepatomegaly, and nephromegaly. Antimicrobial susceptibility test results demonstrated that HNHB was sensitive to five antimicrobials including ceftazidime (MIC=0.32 μg/mL) and polymyxin (MIC=0.01 μg/mL) but resistant to florfenicol (MIC=128 μg/mL) and meropenem (MIC=160 μg/mL). [Conclusion] A strain of A. caviae, designated HNHB, was successfully isolated and identified from the visceral organs of deceased pigs. The isolated strain demonstrated pathogenicity in Kunming mice and exhibited a multidrug-resistant phenotype.