雏鸡源致病性粪肠球菌的分离鉴定及其耐药性分析

【背景】粪肠球菌(Enterococcus faecalis)是人和动物肠道正常菌群之一,也是一种条件性致病菌。近年来,粪肠球菌引起人和动物感染的报道越来越多。【目的】探明引起某养鸡场雏鸡发病死亡的病原及其致病性和有效治疗药物。【方法】结合临床症状和病理剖检,开展病原菌分离、生理生化特性检测和16S rRNA基因序列分析、致病性试验、耐药分析和对患病鸡群的药物治疗。【结果】患病鸡有昏睡、瘫痪或共济失调等临床症状;肝、脾肿大,肝脏发黄、少量出血点、质脆易碎,肠道粘膜增厚、出血,脑轻微水肿;从肝脏组织分离得到一株革兰氏阳性球菌,经纯化培养后命名为CJ517;依据该菌株形态特征、生理生化特性和16S rRNA基因序列分析鉴定为粪肠球菌;致病性试验显示CJ517菌株能致死小鼠,致死率为66.67%;该菌对头孢噻肟、磷霉素、丁胺卡那等药物敏感,对多西环素、卡那霉素、新霉素、氟苯尼考等药物耐药;经用敏感药物和提高免疫力结合治疗后,鸡群病情得到控制。【结论】研究结果可为临床诊断和治疗动物粪肠球菌感染提供参考。

Isolation and identification of pathogenic Enterococcus faecalis from chicks and the analysis of its drug resistance

Background] As a normal intestinal flora of human and animal, Enterococcus faecalis was also a conditional pathogenic bacterium, which could infect human and animal. Objective] To analyze the pathogen of which cause the death of the chicks in chicken farm, and choose the effective drug. Methods] The pathogen was isolated from clinical sample based on the clinical symptoms and pathological examination. Then, the physiological and biochemical characteristics, 16S rRNA gene sequence, pathogenicity and drug resistance were conducted to identify the pathogen. Drug therapy was performed to screen the effective drug towards the pathogen. Results] The clinical symptoms of lethargy, paralysis and ataxia in sick chick could be observed. Swelling spleen, yellow, swelling, brittle and fragile liver with a small amount of bleeding points, thickened and bleeding intestinal mucosa, and mild cerebral edema could be observed by pathological examination. A gram-positive coccus, named CJ517 after purification and culture, was isolated from liver tissue. It was identified as Enterococcus faecalis according to physiological and biochemical characteristics and 16S rRNA gene sequence analysis. The pathogenicity test showed that the mortality rate of CJ517 on mice was 66.67%. It is sensitive to cefotaxime, fosfomycin, butyramecana, while as resistant to doxycycline, kanamycin, neomycin and florfenicol. The disease was relieved after treating with sensitive drug combined immunopotentiator. Conclusion] The result could provide reference for diagnosis and treatment of disease caused by the infection of Enterococcus faecalis.