猪链球菌病单价与多价灭活苗的免疫效果

分别用猪链球菌C、D、E血清群菌株制成两种单价灭活苗S1(C群菌株苗)、S2(D群菌株苗);一种二价灭活苗S3(C、D群菌株苗)和一种三价灭活苗S4(C、D、E群菌株苗)。四种灭活苗经免疫家兔和断奶仔猪后,比较血清抗体水平,四种疫苗的各群抗体水平均能规律性地转阳,其抗体水平间无明显差异。四种疫苗分别免疫小鼠2周后采用强毒进行攻击,它们对相应的血清群强毒株的攻击均能保护,且保护数无明显差异,结果显示多价灭活苗能够保护相应的致病血清群强毒株的攻击,其保护效果与单价灭活苗无差异。     

猪链球菌病综合防制方略

猪链球菌病是一种人畜共患的急性、热性传染病,由C、D、E及L群链球菌引起的猪的多种疾病的总称。文章通过对感染链球菌病猪的临床表现、剖检变化、以及大量的临床病例分析,总结出了一套行之有效的综合防制方案,为该病的预防与治疗提供了依据。     

猪链球菌2型毒力因子多重荧光PCR检测方法的建立与应用

本研究通过在扁桃体组织中添加猪链球菌2型菌后提取的DNA为模板，建立了检测猪链球菌2型毒力因子MRP和EF的多重荧光PCR检测方法，并对部分猪扁桃体和肌肉组织进行了检测。结果发现，本方法可以快速检测出组织内的致病性猪链球菌2型，且特异性强，灵敏度达到100CFU。采用本研究建立的方法对北京和江西部分屠宰场猪扁桃体及北京市售猪肉进行检测，没有发现致病性猪链球菌2型感染。本检测方法的建立，有利于快速确定人-猪链球菌感染原的致病性，这为疫情发生后，有针对性地采取紧急防控措施、保护消费者的健康和生命安全奠定了基础。     

反刍动物发生瘤胃酸中毒的营养机制及其防治

瘤胃酸中毒是危害反刍动物常见的一种代谢病。其产生的主要原因是反刍动物日粮中含有大量易发酵的碳水化合物饲料或者日粮粗纤维含量较低,导致瘤胃产生乳酸过多,引起瘤胃微生物区系失调和瘤胃功能紊乱而造成的。本文就酸中毒的发病机理、防治措施等几方面进行了论述。     

水貂肺炎链球菌病的诊断与防治措施

在发生急性死亡的水貂脑中分离到9株细菌，经细菌培养、染色镜检、生化试验、动物试验证实分离菌株均为肺炎链球菌。药敏试验结果：分离菌株大部分对氟苯尼考、阿米卡星、头孢噻肟、氨苄西林、呋喃妥因敏感，应用敏感抗菌素与疫苗紧急免疫的方式，对该病的综合防治措施做了一系列探索式研究，并取得了理想的防治效果。     

The demonstration and characterization of deoxyribonucleases of streptococci group A, B, C, G and L.

Streptococcus pyogenes, S. agalactiae, S. dysgalactiae, S. equi, S. equisimilis, S. zooepidemicus, Streptococcus group G and L were found to produce deoxyribonucleases (DNases) which were demonstrated using the Toluidine Blue DNA Agar (TDA) described for staphylococcal DNases. The activity of streptococcal DNases increased in the presence of Mg⁺⁺ and Ca⁺⁺ ions, the pH optimum was about 7.5 and native DNA was the best enzyme substrate. It is consequently recommended to modify the TDA according to these results for the demonstration of streptococcal DNases. All streptococcal DNases, except the DNase of S. zooepidemicus, were found to be heat-stable. Isoelectric focusing was a convenient technique for separation of streptococcal DNases and for estimation of the pI values of the DNases. S. agalactiae and S. dysgalactiae generally exhibited distinct species specific patterns in the isoelectric focusing experiments. The DNases produced by S. pyogenes were serologically related to the DNases of S. dysgalactiae and Streptococcus group G. A similar relationship was demonstrated between the DNases produced by S. equisimilis and Streptococcus group L.     

广西罗非鱼链球菌病病原的生化鉴定及药敏试验

从来自南宁、北海等地的十几个暴发疾病的罗非鱼养殖场发病罗非鱼中,分离得到了8株链球菌。通过生化鉴定及药敏试验,结果表明,分离到的8株致病性链球菌,有6株为海豚链球菌（streptococcus iniae）,2株为无乳链球菌（streptococcus agalactiae）。     

酸奶发酵菌株特性的研究

通过对酸奶发酵菌株保加利亚乳杆菌(Lb)和嗜热链球菌(St)在培养基中的活菌数、OD值及pH的研究,得出两菌最适收获期分别是16 h、14 h;两菌1:1混合接种发酵效果优于单株发酵且在脱脂乳培养基中活菌数达到8.5×108cfu/g.     

致病性猪链球菌的分离鉴定及药敏试验

对豫北9个发病猪场采得的22份病料,通过鉴别培养基培养、生化试验,确定猪致病性链球菌16株分属C群、D群、E群和L群,分别对其进行药物敏感性试验。结果表明,链球菌对头孢噻呋、氟苯尼考和磺胺六甲氧嘧啶等多种药物敏感,对土霉素、链霉素等少量药物产生耐药性。     

Analysis of Streptococcus agalactiae‐induced liver injury in tilapia (Oreochromis niloticus)

Streptococcosis, a bacterial disease for multiple fish species, especially tilapia, caused more disruption to the fish culture industry. However, the underlying mechanisms for the occurrence of streptococcosis remain unclear. The aim of this study was to study the effects of streptococcus on the liver of tilapia. In this study, tilapia were injected streptococcal solution (0.05 ml/10 g body weight) and collected blood and liver at 4, 8, 24, 48, 72, 96, 120 and 144 hr after injection. The results showed that the activities of glutamate oxalate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (AKP) and superoxide dismutase (SOD) in the serum of tilapia exhibited irregular changes: increase at first, then decrease and increase again. The levels of total antioxidant capacity (T‐AOC), glutathione (GSH) and malondialdehyde (MDA) showed a decreasing tendency in serum after injection, except GSH at 4 hr. The activity of catalase (CAT) decreased in serum at 4, 24, 120 and 144 hr after injection of streptococcal solution, while the content TP enhanced in serum at 48, 72 and 120 hr after injection. Observations of pathological sections showed obvious damage to the liver tissue structure in response to streptococcal infection. Western blotting revealed an increase in ikkbeta (Ikkβ) protein with prolonged infection time and a decrease in NF‐kappa‐B inhibitor alpha (IkB‐α) and ikappab kinase alpha (Ikkα) proteins. The gene expression of cytochrome P4501A (CYP1A) was downregulated in liver at 24 and 48 after injection, while the mRNA levels of heat stress protein 70 (HSP70) and tumour necrosis factor alpha (TNF‐α) increased at 48 and/or 72 hr. Taken together, our findings confirmed that streptococcus can cause serious damage to the liver of tilapia.