禽源大肠杆菌L型诱导及对常用抗菌药物敏感性研究

为了研究大肠杆菌L型,以氨苄青霉素作为诱导剂,采用药物纸片法对细菌进行反复传代,革兰氏染色及细胞壁染色、镜检,观察菌落及菌体形态,对稳定的L型菌进行致病性及药物敏感性试验。结果表明,大肠杆菌经11次传代可形成稳定的L型菌,且该L菌具有致病性;L型菌对氨苄西林、头孢他啶、头孢唑啉具有一定的耐药性。本研究为开展L型菌检测及指导临床用药提供理论依据。     

支原体研究:历史回顾与热点分析

支原体研究始于1898年。支原体不仅是目前已知能自由生活的最小微生物,在自然界中广泛存在,很多种类还是动植物和人类的重要病原体,加上体外培养的细胞常常被多种支原体污染,其体积很小,能通过细菌滤器,因此支原体曾在最初的好几年中都被认为是一种病毒。随后,人们发现了L型细菌,这种细菌和支原体形态相似,它也具有奇特的"油煎蛋"样菌落,于是,支原体与这种部分或全部缺失细胞壁的L型细菌混淆。20世纪五六十年代,关于支原体的文献对将支原体定义为L型细菌存在分歧。直到60年代末期,用DNA杂交技术获得的第一份基因分析数据,排除了支原体与稳定L型细菌的任何关系。现在已经认为L型细菌是有细胞壁的。尽管如此,从长远发展的眼光来看,将支原体与L型细菌联系起来也不是完全错误的。尽管现在对支原体已不陌生,但对微生物学家来说,支原体的性质、与其它微生物的关系和分类学情况在很长一段时间里都是谜团。因此,支原体研究越来越备受关注。本专题从支原体细胞形态学、生态学、体外培养、代谢途径、基因组测序、构建合成、致病机制研究,以及支原体黏附、抗原变异、免疫系统的调节作用等进行了全面系统的阐述,供兽医工作者参考。     

L型细菌的研究进展

<正>L型细菌(bacterial L-form,细菌L型)是细胞壁缺陷型细菌,菌落形态类似支原体。早在20世纪30年代,研究者就提出了L型细菌的概念;随着研究的深入,人们对L型细菌的临床意义和应用价值的认识逐步加深。     

鸟肠球菌L型的分离与鉴定

细菌L型是细菌在体外受到各种直接或间接损伤细胞壁的理化和生物因素的影响，其细胞壁受到破坏或合成受阻而转化成一种细胞壁缺失或缺陷的细菌。细菌侵入人或动物体后可因体内种种因素，如机体免疫和使用抗菌药物等的影响，出现细胞壁缺损而形成L型。     

猪胆囊中沙门菌L型的分离培养与invA基因检测

为了解猪胆囊中沙门菌L型携带情况,在贵阳市屠宰场采集970例健康生猪的胆囊组织与胆汁标本,用常规细菌学方法和非高渗分离培养法分离沙门菌及其细菌L型,用PCR和核酸序列分析方法对稳定L型纯培养物进行沙门菌的invA基因检测。结果显示,970例生猪胆囊标本未检出沙门菌细菌型,细菌L型检出率为8.25%;80例细菌L型分离物中有50例invA检测阳性,占5.15%;占细菌L型阳性分离物62.50%。研究结果为生猪胆囊沙门菌L型感染的流行病学及其检查提供了依据。     

氨苄西林诱导大肠杆菌L型的试验研究

为诱导大肠杆菌L型,以氨苄西林作为诱导剂,采用药物纸片法进行反复传代,对抑菌圈边缘菌落进行涂片、革兰氏染色及细胞壁染色、镜检,观察其菌落及菌体的形态,并对获得的稳定细菌L型进行致病性试验,以期为兽医临床开展L型菌检测及其相关试验提供理论基础.结果表明,采用氨苄西林药物纸片(200μg/片)经过9次传代,可获得稳定的细菌L型,且该L型菌具有致病性.     

群体感应系统调控细菌生物膜的研究进展

主要介绍了细菌生物膜的概念及其形成过程、细菌群体感应（QS）的概念以及革兰阴性菌的AHL-LuxI/LuxR型QS系统、革兰阳性菌的QS系统、LuxS/AI-2介导的种间QS系统、AI-3/肾上腺素/去甲肾上腺素信息系统4种QS系统的调节机制。就QS系统在细菌中发挥的作用以及对生物膜的调控进行初步阐述,以期为乳酸菌的开发利用和致病菌耐药性的研究提供参考。     

大黄水提物对猪链球菌生物被膜形成的蛋白质表达的影响

为了考察大黄水提物对2型猪链球菌生物被膜形成的蛋白质表达的影响,探索大黄水提物干预猪链球菌生物被膜形成的作用机制,试验利用iTRQA技术测定亚抑菌浓度的大黄水提物干预2型猪链球菌生物被膜形成中蛋白质的表达,从参与细胞代谢活动和分子功能的角度分析细菌不同部位的差异蛋白,并对差异蛋白间的作用关系进行String分析。结果表明:药物对细菌生物被膜形成的57个蛋白表达产生影响,其中上调蛋白34个、下调蛋白23个。这些差异蛋白主要参与代谢、催化、RNA结合及蛋白质合成等活动。核糖体差异表达蛋白间具有显著的交互作用,主要为50S核糖体蛋白和30S核糖体蛋白。说明大黄水提物可能是通过干扰QS系统、细菌的黏附及蛋白质表达来抑制2型猪链球菌生物被膜的形成。     

猪胸膜肺炎放线杆菌生物被膜形成与抑制机制的研究

猪胸膜肺炎放线杆菌(App)引起猪的慢性呼吸道感染,给养猪业造成重大的经济损失。细菌生物被膜(BBF)是细菌为适应自然环境,吸附于生物材料或机体腔道表面保护细菌逃逸形成的细菌群落,由此引起的相关感染性疾病及慢性感染的反复发作称为细菌生物被膜病。App生物被膜(BF)属于菌体外具有空间结构的聚合物,其形成受多种基因调控,其中多药耐药外排泵和Ⅰ型分泌系统关键成分TolC基因缺失导致AppBF黏附减弱;Clp蛋白水解复合物的催化核心ClpP基因缺失引起BF形成受到抑制;App外膜脂蛋白VacJ促进BF的形成;活性酶LuxS基因缺失显示增强AppBF的形成,并减少细菌黏附能力;Adh基因缺失明显降低细菌的积聚、BF形成和对宿主细胞黏附。文章从分子水平上阐述AppBF形成或抑制机制,为探讨防制其生物被膜病提供参考依据。     

细菌Ⅲ型分泌系统装配的研究进展

细菌Ⅲ型分泌系统的发现是病原菌致病机理的重大发现。病原菌为了生存和进入真核宿主细胞,经过长期进化逐渐形成了入侵宿主细胞的特异性机制,其中最显著的机制是细菌Ⅲ型分泌系统(T3SS)。T3SS可以将病原菌效应蛋白直接注入宿主细胞中。最初T3SS只是在少数的致病菌中发现,后来在人类、动物甚至植物的共生菌或益生菌中都有发现。近几年在T3SS的结构、装配以及致病机理的研究上取得巨大的进展。研究T3SS的装配不仅有助于探索病原菌的致病机制,还对研究细胞器装配和蛋白分泌有很大的帮助。     

On the importance of bacterial L-forms in pigeons

Following a definition of bacterial L-forms and a literature review on introduction and reversion of bacteria to and from L-forms, respectively, the results of a study comprising 587 samples (316 pigeons and 271 pigeon eggs) are reported. As a control 25 free living pigeons and 25 eggs of those pigeons were used, because antibiotic treatment of these could be excluded. From 79 samples (75 pigeons and 4 eggs) Salmonella typhimurium var. copenhagen (STMC) was isolated (none from the urban pigeons), of them 11 in the L-form from joints and organs and 3 from eggs. 325 of other bacterial isolates were found as L-forms (= approx. 40%). Out of 168 serum samples investigated, 33.9% showed antibodies against STMC. Corresponding antibodies could only be demonstrated in 73.4% of the pigeons with a STMC isolate. The occurrence of L-forms explains resistance to therapy and the failure of vaccines. The high frequency of L-forms is probably an indication of an inconsequential use of antibiotics in managing pigeon diseases.     

Induction, characterisation and pathogenicity in rainbow trout Oncorhynchus mykiss (Walbaum) of Lactococcus garvieae L-forms.

Difficulties with induction and cultivation of L-forms, particularly those derived from Gram positive parent cells, have constrained to some degree the ability to evaluate the pathogenicity of these morphotypes. Induction of L-forms of Lactococcus garvieae was undertaken using either charcoal or inactivated horse serum media supplemented with ampicillin, benzylpenicillin or erythromycin, the drug of choice for treatment of infections in rainbow trout, Oncorhynchus mykiss, (Walbaum), and NaCl as an osmotic stabiliser. Lysozyme treated cells could be cultured in a cell wall deficient state using media consisting of charcoal, NaCl and either ampicillin or benzylpenicillin. The influence of some amino acids for induction of L-forms was assessed by disc diffusion and combined interaction. Analysis of variance of colony counts indicated that the amino acids glycine, DL-methionine, L-threonine and L-serine (P<0.03), and the presence of charcoal were beneficial and that inactivated horse serum was detrimental to L-form development. Electron microscopy revealed that the cell wall of L-forms was missing and this cell had a greatly expanded volume compared to parent cells. Electrophoresis of whole cell proteins showed some variation of electropherotype between parent and L-form cells. L-forms expressed greater quantities of proteins with molecular mass of 36 and 66 kDa and parent cells contained greater quantities of proteins of molecular mass 29, 43 and 60 kDa. Additional proteins of molecular mass 32, 44 and 53 kDa were present in L-form extracts, and in parent cells of 34, 38, 40, 42, 85 and 123 kDa which may represent cell wall associated proteins or alterations in expression due to different growth rates. Intraperitoneal challenge of rainbow trout with L-forms failed to produce overt infection even in immune-suppressed fish, but L-forms were shown by indirect fluorescent antibody test to remain inkidney tissue. Fish were susceptible to infection when challenged with parent cells of L. garvieae.     

氯化氨甲酰甲胆碱注射液细菌内毒素检查方法研究

建立氯化氨甲酰甲胆碱注射液的细菌内毒素检查方法。按《中国兽药典》2005年版一部收载的细菌内毒素检查法进行试验。试验结果表明,当氯化氨甲酰甲胆碱稀释成0.01 mg/mL时,对鲎试剂的凝集反应无抑制作用。可以用细菌内毒素检查法检查氯化氨甲酰甲胆碱注射液的细菌内毒素。     

细菌生物膜与细菌耐药性研究进展

细菌生物膜是一种包裹于细胞外多聚物基质中的黏附于非生物或生物表面的微生物菌落。作为一种生存策略,绝大多数细菌在合适的条件下都会产生生物膜,生物膜状态下的细菌相对其游离状态有着更强的耐药性,是导致临床上出现难治性感染的重要原因之一。主要综述了生物膜的形成、耐药机制及抗生物膜的策略,以便寻找有效控制生物膜相关感染的手段,指导临床合理用药和新药开发。     

大肠埃希菌生物被膜研究进展

细菌生物被膜指多个细菌黏附于机体或物体表面,分泌胞外多聚物将其自身包裹其中而形成的结构。研究表明人类许多细菌感染与生物被膜有关,生物被膜具有极高的抗药性和免疫逃逸能力,这也是许多细菌感染难以根除的重要原因之一,近年来已成为医学界关注的热点。大肠埃希菌是最重要的条件致病菌之一,论文从大肠埃希菌生物被膜的形态结构、检测方法、耐药机制、应对策略4个方面综述了大肠埃希菌生物被膜研究的进展。     

Comparative studies of the paraspecific immunostimulation (paramunization) by bacterial lysates in bacterial infection models and in the cytotoxicity test

Bacterial lysates of different bacterial strains (E. coli, B. bronchiseptica, P. haemolytica) were prepared by heating, acid- and alkaline-hydrolysis. Lysates were tested for their immunostimulating effect in bacterial infection models and with chromium 51 test demonstrating spontaneous (natural) cytotoxicity. Lysate production was standardized by protein- and Lps-determination. The alkaline-hydrolysis reduced toxicity of Lps and increased the content of soluble bacterial protein. Heating and acid-hydrolysis did not alter bacterial suspensions with respect to Lps-toxicity and protein-content. Mice infected with P. aeruginosa, P. multocida, E. coli and L. monocytogenes (5-10 LD50) had a significantly longer survival time after prophylactic immunostimulation with bacterial lysates than control animals. No protection was observed in immunostimulated mice infected with Erysipelothrix rhusiopathiae. In the Pseudomonas infection model, bacterial lysates prepared by alkaline-hydrolysis had a 10 times higher immunostimulating effect than lysates prepared by acid-hydrolysis or heating. Bacterial lysates stimulated spontaneous cytotoxicity of natural mouse peritoneal killer cells after intraperitoneal application. Whole bacterial lysates had a higher NK-activity as their corresponding purified lipopolysaccharide portion.     

Bacterial translocation in critical illness

Bacterial translocation involves the passage of intestinal bacteria to extraintestinal sites and has been shown to increase morbidity and mortality in critical illness. This review outlines the pathophysiology of bacterial translocation, host defence mechanisms, and reviews the evidence for the clinical management of critically ill patients in order to minimise the negative outcomes associated with bacterial translocation.     

Aerobic bacterial isolates in horses in a university hospital, 1986-1988

Bacterial isolations were reviewed from equine trachea, guttural pouch, uterus, wounds, abscesses, blood, synovial fluid, and abdominal fluid submitted to the Clinical Bacteriology Laboratory of the School of Veterinary Medicine at the University of Montreal for aerobic bacterial culture from 1986 to 1988. Of the 733 samples submitted, 324 (44%) were positive for bacterial growth, and 233 antimicrobial sensitivity tests were performed. Seventy-six percent of all positive samples yielded one bacterial species and two were isolated from 22% of positive samples. Streptococcus zooepidemicus, Escherichia coli, and Actinobacillus spp. were isolated from 39%, 18%, and 15% of the samples, respectively.

Bacterial growth was most common from guttural pouches, wounds and abscesses, and transtracheal washes (TTW), but was less common from uterus, blood, abdominal fluid, and synovial fluids. Streptococcus zooepidemicus was the most common bacterium recovered from guttural pouches, TTW, uterus, and wounds and abscesses. Escherichia coli predominated in abdominal fluids, blood, and synovia. Bacterial sensitivities to common antimicrobials are presented.

     

Flotation of mastitis pathogens with cream from subclinically infected quarters. Prospects for developing a cream-rising test for detecting mastitis caused by major mastitis pathogens

Bacterial isolates, originating from 36 subclinically infected quarter milk samples, were labelled with 75Se and checked for cream-rising at various temperatures in a system analogous to the ABR test ("Abortus Bang Ringprobe"; the cream-rising test based on stained brucella organisms for detection of brucellosis). Diagnostic specificity and sensitivity were analyzed in experiments where labelled bacterial isolates were mixed with a number of quarter milk samples with known bacteriological status as well as samples from healthy control quarters. Creaming at 37 degrees C resulted in specific "recognization" as the bacterial isolates showed preferential flotation in the milk samples from which they had been isolated as well as is milk samples harbouring the same bacterial species. At lower creaming temperatures, the specificity was lost since all the isolates became concentrated in the cream phase irrespective of the milk sample. When comparing the specific recognization by cream of the respective bacteria, bacterial species vary: The prospects for developing diagnostic cream-rising tests for Streptococcus agalactiae, Staphylococcus aureus and Escherichia coli seems promising, but less so for coagulase-negative staphylococci, Streptococcus dysgalactiae, and Streptococcus uberis. The mechanism behind the cream-rising of labelled bacteria at 37 degrees C seems to lie in specific fat globule membrane-bound immunity of IgA type. Therefore the milk fat globules from chronically infected quarters function as absorbents for the respective isolates. Flotation of bacteria with cream indicates an in vivo mechanism enabling bacteria to invade the upper parts of milk ducts within the udder.(ABSTRACT TRUNCATED AT 250 WORDS)     

转移因子注射液中细菌内毒素检测方法研究

为检测转移因子(TF)注射液中细菌内毒素,本研究采用鲎试剂与细菌内毒素产生凝集反应的凝胶法对国内1个生物制品厂的TF注射液样品进行了检测,实验结果表明当TF注射液稀释至0.025 mg/mL时,对鲎试剂的凝集反应无干扰作用.因此,该方法适用于TF注射液中细菌内毒素检测,并可以用于该项生物制品的质量监控.