【摘要】 为了调查江苏省盐城国家级珍禽自然保护区野禽粪便样品中携带的细菌及其致病性，本实验通过对粪便样品经3种培养基分离培养后挑取典型菌落经革兰氏染色镜检，进行生化试验，进一步通过PCR扩增分离菌16S rRNA基因并测序，采用BLAST比对分析后利用MEGA11软件构建其系统发育树，确定细菌种类。结果显示，血琼脂培养基出现光滑湿润的灰白色菌落，麦康凯琼脂培养基出现无色圆形透明菌落，Salmonella Shigella（SS）培养基出现无色圆形半透明菌落，革兰氏染色显示分离菌为革兰氏阴性短杆菌；分离菌能发酵葡萄糖，氨基酸、甲基红M-R和赖氨酸脱羧酶试验均为阳性；经PCR扩增到1 410 bp的16S rRNA基因序列，测序后分析结果显示其与类志贺邻单胞菌16S rRNA基因序列的同源性高达99%以上，系统发育树结果显示，该分离菌与类志贺邻单胞菌16S rRNA基因聚为同一分支。采用K-B纸片扩散法检测分离菌对8类21种抗菌药物的敏感性；将分离菌分别以每只5×10⁸cfu、5×10⁷cfu、5×10⁶cfu、5×10⁵cfu和5×10⁴cfu腹腔注射感染小鼠，评估分离菌的致病性，剖检并取前3个高剂量组小鼠脏器制作病理切片并观察。药敏试验结果显示，该菌株对氨基糖苷类的庆大霉素及新霉素、大环内酯类的红霉素、利福霉素类的利福平和β-内酰胺类的氨苄西林等8种药物耐药，具有多重耐药性；小鼠致病性试验结果显示分离菌对小鼠的LD₅₀为2.81×10⁷cfu，剖检发现死亡小鼠肠道糜烂并有积液，肺淤血，肝脏和脾脏肿大淤血；组织病变观察可见前2个高剂量组小鼠肺泡壁毛细血管扩张充满大量红细胞，肝组织内有大量蓝染细菌团块，脾组织白髓区红细胞数量增加。本研究证实野禽源类志贺邻单胞菌的多重耐药性和对小鼠的致病性，为人兽共患病防控和野生动物病原学研究提供了数据参考。更多还原

【Abstract】 To investigate the bacteria carried in feces samples of wild birds from Yancheng National Rare Bird Nature Reserve in Jiangsu Province and their pathogenicity, the isolated bacterium was preliminarily identified through bacterial isolation and culture,Gram staining and biochemical tests. Subsequently, the 16S rRNA gene was amplified by PCR and sequenced, and a phylogenetic tree was constructed to determine the bacterial species. The results showed that the isolated bacterium formed smooth and moist graywhite colonies on the blood agar medium, and colorless, round, transparent colonies on MacConkey agar medium, and colorless,round, semi-translucent colonies on Salmonella-Shigella（SS） agar medium. The isolated bacterium was identified as a Gram-negative rod. The strain fermented glucose, and tested positive in the amino acid utilization test, methyl red（M-R） test, and lysine decarboxylase test. The 16S rRNA gene sequence（1410 bp） amplified by PCR was analyzed and showed more than 99% homology with the sequence of Plesiomonas shigelloides. The phylogenetic tree placed the isolated strain in the same branch as Plesiomonas shigelloides. The sensitivity of the strain to 21 antimicrobial agents in 8 classes was tested using the Kirby-Bauer method. Finally, the pathogenicity of the strain was evaluated by intraperitoneal infection of mice with doses of 5×10⁸ cfu, 5×10⁷ cfu, 5×10⁶ cfu, 5×10⁵ cfu and 5×10⁴ cfu per mouse. The histopathological sections were prepared from the organs of mice in the top three high-dose groups. The antimicrobial susceptibility test results showed that the strain was resistant to eight drugs, including aminoglycosides（gentamicin and neomycin）, macrolides（erythromycin）, rifamycin（rifampicin）, and β-lactams（ampicillin）, exhibiting multi-drug resistance. The mouse infection experiment results showed that the median lethal dose(LD₅₀) of the strain for mice was 2.81×10⁷ cfu. Necropsy of dead mice revealed erosive intestine with effusion, congested lungs and enlarged and congested liver and spleen. Histopathological examination revealed that alveolar wall capillaries of the first two high-dose groups were dilated and filled with a large number of red blood cells. There were a large number of blue-stained bacterial aggregates in the liver, and an increased number of red blood cells in the white pulp area of the spleen. This study clarified the multi-drug resistance of Plesiomonas shigelloides from wild birds and its pathogenicity to mice, providing data references for the prevention and control of zoonoses and the study of wildlife etiology.更多还原