嗜热链球菌的分离鉴定及牛乳样中抗菌药物残留的检测

通过对TTC法中指示菌株嗜热链球菌的分离及分离菌抗生素敏感性的分析,对57份不同来源、不同品牌的牛乳样中抗生素残留进行了检测。结果表明,分离菌对氨苄西林(AMP)耐药;12份牛乳样有抗生素残留,2份乳样可疑;指示菌的耐药性对牛乳中抗生素残留的检测有影响。     

赛里木拉丝酸奶中优势菌株发酵乳对血管紧张素转化酶的抑制作用

利用改进的紫外分光光度法,测定从新疆赛里木拉丝酸奶中分离出的瑞士乳杆菌mb2-1、嗜热链球菌mb5-1以及马克斯克鲁维酵母Y6单菌和混菌发酵脱脂乳对血管紧张素转化酶抑制率。结果表明:瑞士乳杆菌mb2-1、嗜热链球菌mb5-1单菌发酵对血管紧张素转化酶抑制率48h达到最高,分别为70.75%、47.17%;与马克斯克鲁维酵母Y6混合发酵48h,对血管紧张素转化酶抑制率分别为75.68%和44.85%。     

Bacteriological and Molecular Detection of Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus in Equines of Northern India

Present study was undertaken to study the prevalence of β-haemolytic streptococci in equine of northern temperate region of Jammu and Kashmir, India. One hundred and forty one samples were collected in duplicate from nasopharyngeal tract of diseased (53) and apparently healthy equine (88) for isolation and direct PCR. A total of 77 isolates of streptococci were recovered from 141 samples with an overall prevalence rate of 54.60%. Out of these 77 isolates, 52 were from diseased and 25 from apparently healthy animals. Of the 77 isolates, 4 were identified as Streptococcus equi subsp. equi, 56 as S. equi subsp. zooepidemicus and 17 as S. dysgalactiae subsp. equisimilis. Thus the overall prevalence of S. equi subsp. equi, S. equi subsp. zooepidemicus and S. dysgalactiae subsp. equisimilis was 2.83, 39.71 and 12.05% respectively. The sensitivity of the PCR for the detection of S. equi species was found higher when attempted from direct swab samples.     

猪链球菌2型山东强毒株的分离鉴定

对某养猪场发生呼吸道感染及神经症状的病猪脑组织进行了病原菌分离,对其优势菌进行菌落形态学观察、生化试验、PCR检测、药敏试验和毒株致病力试验.结果显示,成功分离到1株猪链球菌2型,其含有目前已知的mrp、sly、ef3种毒力基因,该菌株对昆明系小鼠、新西兰白兔具有一定的致病性,动物回归试验证实该菌株对断奶仔猪具有较强的致病性.     

Culture results from milk samples submitted to veterinary diagnostic laboratories from August 2003 to December 2006 in New Zealand

Abstract

AIMS: To determine the pattern of isolation of major mastitis-causing organisms isolated from milk samples submitted to five veterinary diagnostic laboratories in New Zealand.

METHODS: The culture results of 25,288 milk samples that were collected from dairy cows throughout New Zealand from August 2003 to December 2006 and submitted to a group of veterinary diagnostic laboratories were assembled, reviewed and summarised. Logistic regression was used to analyse the effect of year, region (i.e. North vs South Island), and season on the probability of isolating the two most common organisms.

RESULTS: The most commonly isolated mastitis causing organisms from all samples were: Streptococcus uberis (23.6%), Staphylococcus aureus (23.5%), coagulase-negative staphylococci (CNS; 7.2%), Strep. dysgalactiae (6.2%), Bacillus spp. (4.0%), and coliforms (3.7%). The percentage of samples with isolates of Strep. uberis or Staph. aureus was affected by island, year and season (p<0.001). For most of the year, except in late winter and early spring when Strep. uberis was much more common, the percentage of isolates of Strep. uberis and Staph. aureus were not apparently different despite the former being an environmental pathogen and the other a contagious one.

CONCLUSION: The pattern of isolation of major mastitis-causing organisms, as determined from culture of milk samples submitted to diagnostic laboratories in New Zealand, has changed significantly over the last 40 years, with a substantial increase in the percentage of isolates that are Strep. uberis and a decrease in isolates of Strep. agalactiae. There is a clear seasonal pattern to the isolation of both Strep. uberis and Staph. aureus, particularly the former.

CLINICAL RELEVANCE: Knowledge of the aetiological agents causing bovine mastitis on a farm is of value in determining the choice of treatment. This dataset shows that, although there is seasonal pattern to the isolation of mastitis-causing organisms in New Zealand, both Strep. uberis and Staph. aureus are isolated throughout the year, so bacteriology is of value in determining aetiology even in late winter/early spring.     

猪链球菌保护性抗原表位串联亚单位疫苗设计及小鼠免疫保护效力分析

为了筛选和鉴定猪链球菌3个保护性抗原GAPDH、MRP、DLDH的优势B细胞抗原表位,设计表位串联方案,研究重组串联表位蛋白(简称GMD蛋白)免疫小鼠后对猪链球菌攻击的免疫保护效力。采用生物信息学分析工具对优势B细胞抗原表位进行筛选,并将表位串联并构建重组质粒pET28a-GMD,诱导表达且纯化后将GMD蛋白配合弗氏佐剂免疫BALB/c小鼠,并评价该蛋白对2型猪链球菌的免疫保护效力。发现经SDS-PAGE鉴定该重组蛋白大小为43.3 kDa;小鼠免疫保护实验结果显示,免疫小鼠血清中针对猪链球菌HA9801菌株抗体效价最高可达1∶102 400,GMD蛋白对小鼠的免疫保护率可达90%。上述结果表明面对猪链球菌HA9801菌株的攻击,GMD蛋白可以为机体提供良好的免疫保护,本研究结果为猪链球菌新型表位亚单位疫苗的研制提供了基础数据。     

奶牛隐性乳房炎三种致病菌的多重PCR检测方法的建立

为建立快速并能同时检测无乳链球菌、金黄色葡萄球菌、绿脓杆菌3种奶牛隐性乳房炎致病菌的方法,根据无乳链球菌16S rRNA基因、金黄色葡萄球菌NUC耐热基因、绿脓杆菌ETA基因序列并参考文献各合成一对特异性引物,通过对PCR反应各项参数的调整优化,建立多重PCR检测体系,并同时进行灵敏性试验和特异性试验。结果显示:该检测方法可以同时扩增出无乳链球菌270 bp、金黄色葡萄球菌153 bp和绿脓杆菌375 bp的特异性片段以及细菌16S rRNA 1 500 bp的通用片段,而对于其他的6种病原菌只能扩增出1 500 bp的通用片段,具有较强的特异性。三种特异性引物扩增条带与GenBank上的细菌基因序列同源性为99%。增菌培养24 h,该体系对无乳链球菌、金黄色葡萄球菌、绿脓杆菌的最低灵敏度分别为8×10⁴、4×10⁴、1.5×10⁵ CFU·mL^-1。本研究建立的检测方法能够完成无乳链球菌、金黄色葡萄球菌、绿脓杆菌的快速检测,对于生产上奶牛隐性乳房炎的鉴别诊断和快速检测具有重大意义。     

外源添加氨基酸对兽疫链球菌产透明质酸的影响

兽疫链球菌(Streptococcus zooepidemicus)是一种营养缺陷型菌株,其生长代谢需要外源添加各类营养因子。通过在兽疫链球菌发酵对数生长初期外源添加氨基酸的方式研究其对透明质酸生产的影响。结果表明,外源添加氨基酸对透明质酸的生产具有显著的促进作用。笔者初步研究了当添加质量浓度为0.5 g/L时,18种常见氨基酸对透明质酸产量的影响。在此基础上,在18种氨基酸中选取苯丙氨酸和丝氨酸对透明质酸合成进行浓度优化实验,结合细胞生长和代谢产物分析,更进一步研究氨基酸对透明质酸合成的影响。结果表明,苯丙氨酸和丝氨酸添加质量浓度分别为0.5 g/L和0.5 g/L时,透明质酸产量提高最大,与对照相比分别提高了18.05%和17.44%,菌体浓度均没有增加,但是乳酸浓度分别降低了9.93%和15.80%,说明氨基酸的添加不是通过增加菌体量来提高透明质酸产量,而是改变了碳源流向,减少了乳酸积累,使得透明质酸产量显著提高。本研究为高产透明质酸的发酵工艺提供了借鉴与依据。     

Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice

Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.