Enhanced intraphagocytic killing of Brucella abortus in bovine mononuclear cells by liposomes-containing gentamicin

In vitro intraphagocytic killing of Brucella abortus in bovine mononuclear leukocytes was enhanced by cationic, anionic, and neutral multilamellar liposomes-containing gentamicin. Free gentamicin not entrapped in liposomes. and liposomes without antibiotic did not enhance intraphagocytic killing of B. abortus in bovine phagocytes. In vivo killing of B. abortus in guinea pigs was also enhanced by liposomes-containing gentamicin when compared to free gentamicin. Liposomes-containing alpha tocopherol acetate failed to enhance in vivo killing of B. abortus.     

饲用抗生素的促生长机制

抗生素原称为抗菌素,是指由细菌、放线菌、真菌等微生物经培养而得到的某些产物,或是化学半合成法制造的相同和类似的物质,在低浓度下对特异性微生物(包括细菌、真菌、立克次体、病毒、支原体、衣原体等)有抑制或杀灭作用。自从1946年Moore等发现链生素在肉鸡饲料中具有促生长作用以后,伴随着许多抗生素品种相继问世并工业化生产,研究者们几乎对每个新问世的抗生素都作了以促进动物加速生长为目的的饲养试验,研究结果肯定了多种抗生素具有刺激和加速动物生长的作用。从此,抗生素就开始作为饲料添加剂,广泛应用于饲料中,针对抗生素促生长机…     

乳酸菌的耐酸性机制

<正>乳酸菌是一类能利用可发酵糖产生大量乳酸的细菌的通称。乳酸菌在自然界分布广泛,可栖居于人和动物的肠道以及其它器官内。很久以前人们就利用乳酸菌来发酵动物制品(乳、肉、鱼等)和植物制品(蔬菜、葡萄酒、橄榄等)。随着食品发酵工业的不断发展壮大,开发利用乳酸菌的经济效益也不断在增长。虽然乳酸菌在发酵食品中的含量非常少,但是对食品的感官品质和质量却有决定性作用,因此,发酵剂菌株的质量功能特性和生长特性对于产品的成功发酵是非常必要的。乳酸菌不但包括在食品发酵中使用的一     

Bovine leukocyte phagocytosis and bacteria killing monitored by intracellular acridine orange fluorescence and extracellular fluorescence quenching

The time course of phagocytosis and intracellular killing of serum-opsonized Escherichia coli K12 and Staphylococcus aureus SG511 by glass-adherent bovine peripheral blood polymorphonuclear leukocytes (PMNLs) and cultured monocytes (macrophages) was monitored by fluorescence microscopy of single cells using the acridine orange (AO)/crystal violet (CV) technique. After interaction of glass-adherent leukocytes (20, 40, 60 min, 37 degrees C) with opsonized bacteria, cells were stained with the fluorescent dye AO. Living bacteria stained green, dead bacteria stained orange. The addition of CV to AO-stained bacteria quenched the fluorescence of extracellular bacteria only. CV does not penetrate living bovine PMNLs which allows the discrimination of ingested (fluorescent) and extracellular (nonfluorescent) bacteria during attachment and phagocytosis of bacteria by adherent PMNLs. We investigated quantitatively phagocytosis and intracellular killing of serum-opsonized bacteria by bovine PMNLs from 22 bulls of 4 different Swiss dairy breeds. Within 60 min maximum uptake (approximately 12 bacteria/PMNL) and killing (approximately 80%) of serum-opsonized Escherichia coli K12 and Staphylococcus aureus SG511 were achieved. The AO/CV technique was also used to quantify the uptake and intracellular killing of serum-opsonized Escherichia coli K12 by cultured monocytes (macrophages). Within 60 min maximum uptake of bacteria (approximately 16/MO) was achieved; approximately 83% of bacteria were killed.     

截短侧耳类药物耐药机制研究进展

截短侧耳类抗菌药物泰妙菌素和沃尼妙林是兽医专用药。随着病原菌对现有药物的耐药性在全球范围蔓延,现在兴起了开发新的截短侧耳衍生物用于治疗人类细菌感染。瑞他帕林(Rapamulin)是第一个用于人医的截短侧耳类药物,2007年被批准用于由金黄色葡萄球菌(Staphylococcus aureus)和酿脓葡萄球菌(Staphylococcus pyogenes)引起的皮肤感染。截短侧耳衍生物在人医上的开发应用使其耐药机制成为国际上的研究热点。本文就截短侧耳类药物耐药机制及其传播机理的研究进展进行综述。     

饲用抗生素抗菌药物的合理应用

１抗生素添加剂长期使用的效果及其影响因素１．１抗生素添加剂长期使用的效果尽管抗生素普遍存在耐药性问题，但抗生素添加剂应用４０余年的今天，大量的饲养试验和生产实践表明，抗生素的促生长，提高饲料利用率，控制疾病降低死亡率，提高饲料经济效益的作用仍然是很明显的。Hays（１９７７）和Zimmerman（１９８６）的考察表明，后１０年内猪对抗生素的反应幅度同最初２５年内的反应幅度略有降低，但很接近（见表１）。Sunde（１９８４）对鸡应用抗生素资料的总结也得出类似的结果。可见抗生素添加剂继续使用是有价值的。瑞典养猪业自…     

The role of lysozyme in killing and lysis of coliform bacteria in the bovine animal 2. Effect of absorbing serum with bentonite or bacteria

Adding lysozyme in the presence of EDTA to bentonite-absorbed serum produced variable results in bacteriolytic tests either restoring lytic activity, potentiating existing activity or not affecting activity depending on the organism and serum used. Bactericidal activity, when removed by bentonite, was not restored by adding lysozyme. Absorbing sera with bacteria removed both bacteriolytic and bactericidal activity, the amount removed depending on the number of absorptions. Bacteriolytic, but not bactericidal, activity of sera absorbed with bacteria was restored by added lysozyme in the presence of EDTA. Serum absorbed with zymosar or antigen— antibody precipitates is inactive in bacterial killing.A requirement for added C′ in the bactericidal system can only be demonstrated in high dilutions of serum suggesting that C′ activity rather than antibody is the limiting factor.The experiments show that absorption techniques for removing lysozyme or antibody are non-specific and that lysozyme is involved in lysis but not in the killing of coliforms by bovine serum.     

Effects of various antibiotics on the control of bacteria in boar semen

Nine antibiotics were tested for the control of 11 bacterial genera isolated from boar semen. Of the antibiotics tested, the aminoglycosides dibekacin, amikacin and gentamicin proved fairly effective. Minimum inhibitory concentrations of those antibiotics were low (less than 6.25 micrograms/ml) compared to those of antibiotics commonly used for semen diluents. Seventy-four semen samples were stored at 15 degrees C by means of dialysis in the presence of dibekacin (100 micrograms/ml). After seven days' storage, about 80 per cent of the samples showed no bacterial growth and the mean values for sperm motility an normal acrosomes were 75.4 per cent and 82.7 per cent respectively. Twenty sows which were inseminated with semen stored for up to 14 days produced 16 litters and the average litter size was 9.9.     

中药羊踯躅对钉螺浸杀作用及其机理研究

中药羊踯躅有杀虫作用,用羊踯躅进行钉螺浸杀试验,研究其杀螺效果。将水提取物和乙醇提取物配制成不同浓度的羊踯躅溶液作浸杀钉螺试验,观察钉螺死亡率及羊踯躅对钉螺软组织中总蛋白和糖原含量的影响,并检测羊踯躅提取液对鱼类的毒性。结果表明,羊踯躅有较强的杀螺作用,而且对鱼类的毒性不明显。     

微生物发酵饲料替抗机理研究进展

微生物发酵饲料充分利用益生菌的特性,在饲料业发展前景广阔,其具有改善动物免疫力,提高动物抗病能力等作用。目前面对饲料业全面禁止使用抗生素的趋势,微生物发酵饲料能够作为抗生素的替代品,为绿色饲料业的发展提供强力保障。本文从调节动物机体免疫系统、增加免疫活性物质、改善动物肠道微生态平衡等几个方面对微生物发酵饲料的替抗机理进行了介绍,以期能够为微生物发酵饲料的发展和应用提供帮助。 [关键词] 发酵饲料|抗生素|免疫力|氧化应激     

鸡舍环境耐药细菌气溶胶及其向环境传播的研究

通过对舍内粪便、空气和舍外环境(10、50、100m)中的空气分离到的细菌鉴定，包括细菌DNA分子生物学检测及药物敏感实验以及细菌含量统计学分析，证明三者之间存在着内在联系；舍内环境微生物气溶胶包括耐药细菌通过舍内外气体交换排往鸡舍周围环境，舍周边环境在一定范围内受到生物污染。研究显示，在粪便、舍内空气、舍外环境10、50、100m空气中分离的金黄色葡萄球菌和链球菌80％以上对氯霉素(CMP)和对苯唑青霉素(OXA)耐药；粪便和舍内外环境空气中的80％以上的大肠杆菌和沙门氏菌对氨苄青霉素(AMP）、氯霉素(CMP)、头孢唑啉(CFZ)均为抑制。证明该鸡舍曾经使用过这些药物治疗或作为添加剂在饲料中添加，鸡群产生了耐药细菌菌株，并向环境传播。测量数据统计结果指出，十里河鸡场鸡舍内环境空气中的大肠杆菌、沙门氏菌、金黄色葡萄球菌和链球菌与舍外环境中相应菌群含量比较差异显著或极显著(P＜0．05或P＜0．01)，但舍外10、50、100m之间的相应菌群比较差异不显著(P＞0．05)，这说明鸡舍内环境细菌气溶胶含量产生多，含量高，菌源强度大；另一方面，反应了鸡舍内环境微生物气溶胶包括耐药细菌能向舍外环境扩散，位舍外环境在一定的范围内受到动物源性生物污染，影响范围大于100m。通过对鸡舍环境微生物气溶胶来源的探讨发现，粪便中的大肠杆菌、沙门氏菌、金黄色葡萄球菌和链球菌与舍内空气相应菌群数量关系比较，呈现正相关(r=0.99)。这从一个侧面揭示了粪便可能是微生物气溶胶的主要来源。     

中药复方消毒剂对鸡舍内空气浮游菌杀灭和有害气体降解的实验研究

为了解国内某厂家生产的植物源中药复方消毒剂的对鸡舍现场的空气沉降菌和有害气体降解效果,试验重复3次,每次设计消毒前1h,消毒后1h、4h、10h和24h五个时间监测点,采用了细菌自然沉降法和有害气体检测仪对鸡舍内空气浮游菌含量和氨气、硫化氢等有害气体进行了检测,同时还挑选5个养殖工人对鸡舍内除臭效果感官判定。3个批次结果均显示,消毒剂按1:500和1:1000两个浓度稀释使用4h后,鸡舍现场有效除菌率就达到90%以上;消毒1h后与消毒前比较,对氨气和硫化氢的降解差异显著;消毒24h后,通过养殖工人感官评判,有显著除臭效果。结果表明,该实验设计的中药消毒剂对鸡舍内环境有显著改善作用。     

7种天然化合物对产ESBLs大肠杆菌的增敏机制研究

为了逆转由β-内酰胺酶引起的细菌耐药性,采用紫外分光光度法从天然化合物中筛选出能够抑制β-内酰胺酶的7种天然化合物,并应用"棋盘法"分别测定它们与抗生素联用对产超广谱β-内酰胺酶(ESBLs)大肠杆菌的抗菌活性。结果表明:芦荟大黄素、槲皮素、香紫苏醇、木犀草素、苦参碱、大蒜素和五味子甲素对β-内酰胺酶有不同程度的抑制作用,均可增加抗生素对产ESBLs大肠杆菌敏感性,且其增加程度与其对β-内酰胺酶的抑制作用强度呈正相关,表明此7种天然化合物增加抗生素对产ESBLs大肠杆菌敏感性的机制是通过抑制大肠杆菌产生的β-内酰胺酶,使抗生素免于水解而发挥作用的。该研究为解决由β-内酰胺酶引起的细菌耐药性问题提供了新的思路和途径。     

Evaluation of subgingival bacteria in the dog and susceptibility to commonly used antibiotics

The aim of the present investigation was to evaluate the subgingival aerobic and anaerobic flora of 13 dogs with periodontal disease and the susceptibility of these bacteria to antibiotics currently approved in Italy for treatment of canine infections. Of the anaerobic bacteria, Bacteroides fragilis was most frequently isolated, followed by Peptostreptococcus + Porphyromonas gingivalis and Prevotella intermedia. Of the aerobic bacteria, alpha-hemolytic Streptococcus was most frequently isolated, often associated with Escherichia coli or Pasteurella multocida. Resistance of anaerobic and aerobic bacteria to various antibiotics was generally high. Anaerobic bacteria appeared to be susceptible to amoxicillin + clavulanic acid, doxycycline, and erythromycin; aerobic bacteria appeared to be susceptible to amoxicillin + clavulanic acid, erythromycin, gentamycin, and sulfa-trimethoprim. Bacteroides fragilis was resistant to all of the antibiotics tested. The emerging worldwide problem of bacterial resistance to antibiotics resulting from overuse and misuse of antibiotics is discussed.