罗氏沼虾(Macrobrachium rosenbergii)致病性豚鼠气单胞菌(Aeromonas caviae)的分离鉴定及其特性分析

近年来细菌性疾病因病原菌种类繁多、覆盖区域广而影响了其养殖业的健康发展，造成较大的经济损失。从体表具有黑斑、肢体残损症状的罗氏沼虾(Macrobrachium rosenbergii)肝胰腺组织中分离得到1株病原菌，通过形态学观察、生理生化特性鉴定、16S rRNA序列和特定毒力基因检测鉴定，以及人工回归感染试验和药敏试验分析其致病性和耐药性。结果表明，该菌为豚鼠气单胞菌(Aeromonas caviae)，含有aer、lip、gcat、ser和OMPA I等毒力基因；药敏试验显示其对头孢曲松、氯霉素等7种抗生素高度敏感，对恩诺沙星、阿米卡星及复方新诺明3种抗生素中度敏感，对四环素、环丙沙星等10种抗生素具有耐药性；人工回归感染实验表明该菌具有较高的致病性，对罗氏沼虾的半致死浓度为6.54×10⁵ CFU/mL。豚鼠气单胞菌作为水产养殖中的条件性致病菌，研究结果揭示了该菌株的部分生物学特性，有利于丰富豚鼠气单胞菌属的基础数据，同时也为罗氏沼虾养殖过程中的病害防控提供了一定参考依据。

ISOLATION, IDENTIFICATION, AND CHARACTERIZATION OF PATHOGENIC AEROMONAS CAVIAE IN MACROBRACHIUM ROSENBERGII

Macrobrachium rosenbergii in a farm in Huzhou (Zhejiang, China) showed symptoms such as black spots and limb damage, which could lead to death. To identify the cause of the disease, a pathogen was isolated from the hepatopancreas tissue of M. rosenbergii and was characterized by morphological observation, physiological and biochemical analyses, 16S rRNA sequence, and specific virulence gene analysis. The pathogenicity and drug resistance were analyzed by artificial regression infection test and drug sensitivity test. Results show that the strain was pathogenic Aeromonas caviae, and it contained virulence genes such as aer, lip, gcaT, ser and OMPA I. Drug sensitivity test showed that the strain was highly sensitive to 7 antibiotics (ceftriaxone, chloramphenicol, florfenicol, neomycin, doxycycline, gentamicin, and streptomycin), moderately sensitive to 3 antibiotics (enrofloxacin, amikacin, and cotrimoxazole), and resistance to other 10 antibiotics. The artificial regression infection experiment showed that the bacterium was pathogenic to M. rosenbergii, and the median lethal dose was 6.54×10⁵CFU/mL. A. caviae is a conditional pathogen in aquaculture. This study revealed some biological characteristics of this strain, which is beneficial to enrich the basic data of Aeromonas westermani, and may provide a scientific basis and reference for the prevention and control of diseases in M. rosenbergii culture.