乳酸杆菌对病原菌粘附肉鸡肠粘液的影响

研究嗜酸乳杆菌、禽大肠杆菌O78、大肠杆菌ATCC 25922、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肉鸡不同肠段粘液糖蛋白的粘附性能,探讨嗜酸乳杆菌对四种病原菌的粘附排斥作用.结果表明,在不同的肠道部位,嗜酸乳杆菌、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肠粘液糖蛋白的粘附能力不同,而禽大肠杆菌O78、大肠杆菌ATCC 25922在各肠段粘液上的粘附性能相近;在相同的肠道部位,所试菌与肠粘液糖蛋白的粘附能力有差异,其中嗜酸乳杆菌的粘附作用最强;嗜酸乳杆菌对所试病原菌均有不同程度的粘附排斥作用,其中对鸡白痢沙门氏菌的粘附排斥较强,而对大肠杆菌ATCC25922的则较弱.     

Reciprocal competitive exclusion of salmonella and Escherichia coli by native intestinal microflora of the chicken and turkey

Both the native intestinal microflora of chickens that protected chicks against salmonellae and Escherichia coli and native turkey intestinal microflora were evaluated for their reciprocal protective capacity in both species against Salmonella typhimurium and a pathogenic strain of E. coli. Nalidixic-acid-resistant forms of the S. typhimurium and E. coli strains were used in seeder-bird and individual-bird challenge tests. Reciprocal protection was provided by native chicken and turkey intestinal microflora in chicks and poults against S. typhimurium and the pathogenic strain of E. coli. The chicken and turkey microflora appeared to be equally effective in protecting the two species from S. typhimurium, but protection against E. coli was somewhat greater in the chicken than in the turkey.     

Influence of Mycoplasma gallisepticum, infectious bronchitis, and cyclophosphamide on chickens protected by native intestinal microflora against Salmonella typhimurium or Escherichia coli

Chickens that have considerable resistance to Salmonella typhimurium or Escherichia coli infection by early development of a native intestinal microflora shed these bacteria following aerosol exposure to Mycoplasma gallisepticum and/or infectious bronchitis virus. Administration of cyclophosphamide to similarly treated chickens induced slight shedding of these bacteria, and the combination of cyclophosphamide and respiratory agents magnified the shedding rate. These agents also influenced the isolation rate of E. coli and S. typhimurium from the trachea and air sacs.     

Influence of bacteria on Clostridium perfringens infections in young chickens

When monoflora chickens with Lactobacillus acidophilus or Streptococcus faecalis were inoculated with Clostridium perfringens either in broth culture or resuspended in Gifu anaerobic medium broth or supernatant fluid, few or no chickens died. Approximately 50% of germ-free chickens died after inoculation of C. perfringens culture, whereas no conventional birds died after inoculation of broth culture. C. perfringens in the contents of duodenum from germ-free chickens numbered about 10(4) colony-forming units (CFU)/g after inoculation 10(8) CFU broth culture per bird, but in gnotobiotic and conventional chickens this organism decreased or was not detected. When C. perfringens was cultured in intestinal contents collected from germ-free chickens, C. perfringens proliferated but alpha toxin was not detected. These findings indicate that the pathogenicity of C. perfringens was suppressed by L. acidophilus or S. faecalis administered previously or inhibited by normal intestinal flora.     

Adhesion of bacteria to the cecal mucosal surface of conventional and germ-free chickens infected with Eimeria tenella.

When Salmonella typhimurium and Clostridium perfringens were tested in conventional chickens, larger numbers of S typhimurium and C perfringens adhered to Eimeria tenella-infected ceca than to uninfected ceca. In germ-free chickens, S typhimurium and C perfringens adhered to the E tenella-infected cecal mucosa more than to the uninfected cecal mucosa, but fewer Bacteroides vulgatus and Bifidobacterium thermophilum adhered to the E tenella-infected ceca than to the uninfected ceca. Many bacteria adhered to the lesions caused by E tenella as observed by scanning electron microscopy. On the basis of our findings, we suggest that infection with E tenella upsets the balance of competitive adherence of bacteria, allowing more colonization of S typhimurium and C perfringens.     

Growth of Salmonella typhimurium in the caecum of gnotobiotic chickens with Eimeria tenella

Gnotobiotic chickens infected with Eimeria tenella (5 X 10(4) oocysts per bird) received an oral inoculation of 100 Salmonella typhimurium two, four, six or eight days after coccidial infection at four days old. When S typhimurium was given two or four days after E tenella infection, S typhimurium counts in the caecal contents were similar to the counts in birds infected with S typhimurium alone. When S typhimurium was given six or eight days after E tenella infection, counts of the organism were significantly greater than with S typhimurium infection alone. There were no differences in the number of chickens positive for S typhimurium in the caecal contents, bile, liver and spleen between the two groups.     

Construction and evaluation of a delta cya delta crp Salmonella typhimurium strain expressing avian pathogenic Escherichia coli O78 LPS as a vaccine to prevent airsacculitis in chickens.

Avian pathogenic strains of Escherichia coli cause a number of extraintestinal diseases in poultry, including airsacculitis and colisepticemia. Expression of O78 lipopolysaccharide (LPS) is frequently associated with pathogenic isolates. Salmonella, a common poultry contaminant, is a major public health concern. The purpose of this work was to develop an E. coli vaccine for poultry with the use of an attenuated Salmonella typhimurium carrier that would benefit both the bird and the consumer. Orally administered attenuated S. typhimurium delta cya delta crp strains have been shown to provide excellent protection against wild-type Salmonella challenge in chickens. This work describes the construction of a delta cya delta crp derivative of an avian pathogenic S. typhimurium that expresses both the homologous group B determinants (O1,4,5,12) and the heterologous E. coli O78 LPS O antigens. This was accomplished by inserting the E. coli rfb region, which encodes the genes required for O78 expression, into the chromosomal cya gene of S. typhimurium, creating a defined deletion/insertion mutation. A delta crp mutation was introduced in a subsequent step. Expression of both O antigens was stable in vitro and in vivo. Vaccination of white leghorn chicks at day of hatch and 14 days with the recombinant vaccine strain induced serum immune responses against both S. typhimurium and E. coli LPS and protected the birds against subsequent challenge with an avian pathogenic E. coli O78 strain. Introduction of a mutation in rfc, which encodes the O antigen polymerase, reduced the chain length of the S. typhimurium LPS without affecting the expression of O78. The rfc mutation further enhanced the ability of the vaccine strain to protect chickens against E. coli challenge.     

Expression of Escherichia coli antigens in Salmonella typhimurium as a vaccine to prevent airsacculitis in chickens

Avian pathogenic Escherichia coli strains are associated with a variety of extraintestinal poultry diseases, including airsacculitis, colisepticemia, and cellulitis. A number of E. coli serotypes are associated with these diseases, although the most prevalent serotype is O78. Fimbrial proteins expressed by these strains appear to be important virulence factors, including type 1 fimbriae, P fimbriae, and curli. We have been working to develop an effective vaccine to protect chickens against these diseases. We have previously shown that an attenuated Salmonella typhimurium strain expressing O78 lipopolysaccharide provides protection against challenge with an O78 avian pathogenic E. coli strain. In this work, we have constructed an attenuated S. typhimurium that expresses both the O78 lipopolysaccharide and E. coli-derived type 1 fimbriae. In these studies, chickens were vaccinated at day of hatch and again at 2 wk of age. Birds were challenged at 4 wk of age. We found that the vaccine candidate provided significant protection against airsacculitis as compared to untreated controls or birds vaccinated with an attenuated S. typhimurium that did not express any E. coli antigens. In a separate experiment, challenged vaccinates showed significant weight gain compared to challenged nonvaccinates. We were not able to demonstrate protection against E. coli O1 or O2 serotype challenge, nor against challenge with wild-type S. typhimurium.     

Factors influencing enhanced Salmonella typhimurium infection in Eimeria tenella-infected chickens

To investigate a possible mechanism involved in the enhancement of Salmonella typhimurium infection in chickens concurrently infected with Eimeria tenella, S typhimurium was given orally to chickens 7 days after E tenella inoculation. The number of viable S typhimurium decreased in the ceca of chickens not inoculated with E tenella, whereas the number gradually increased in the ceca of chickens inoculated with E tenella. Cecal contents were analyzed for pH value, oxidation-reduction potential, and amounts of short-chain fatty acids and bile acids. In the ceca of E tenella-inoculated chickens, the oxidation-reduction potential significantly (P less than 0.05) shifted to the oxidative phase, and the concentration of volatile fatty acids (acetic acid, propionic acid, and butyric acid) significantly (P less than 0.05) decreased. In both aerobic and anaerobic incubations, the number of viable S typhimurium in vitro decreased as the molar concentration of fatty acids increased. Experimental evidence indicated that multiplication of S typhimurium in the ceca of E tenella-inoculated chickens was associated with decreased concentrations of volatile fatty acids.     

Escherichia coli colonization of the trachea in poultry: comparison of virulent and avirulent strains in gnotoxenic chickens

In chickens, virulent Escherichia coli strains express their pathogenicity in the respiratory tract. A quantitative comparison of tracheal colonization by virulent and avirulent E. coli was carried out in gnotoxenic chickens after intestinal implantation. Two-week-old axenic chicks reared in isolators were inoculated per os with various associations of identified E. coli strains. No clinical sign of disease was observed in any of the chicks, despite the presence of virulent strains in all the intestines and most of the tracheas. The virulent organism reached greater population sizes in the trachea and feces of monocontaminated chicks and of chicks contaminated simultaneously with a virulent and an avirulent strain. In holoxenic chicks, identified virulent and avirulent strains were outnumbered by the E. coli population of the intestinal flora previously established and could not be recovered from the tracheas of most chicks.     

Inhibition of Salmonella typhimurium in the chicken intestinal tract by a transformed avirulent avian Escherichia coli.

An avirulent, wild-type avian Escherichia coli (E. coli Av) was electrotransformed with a plasmid coding for the production of microcin 24 (pGOB18) and was designated E. coli AvGOB18. The transformant inhibited the growth of seven serotypes of Salmonella commonly associated with colonization and contamination of poultry products and seven strains of E. coli O157:H7 in the in vitro colicin/microcin assay. The transformant did not inhibit the replication of multiple isolates of Listeria monocytogenes or Campylobacter jejuni in similar assays. The transformant is nonconjugative, indicating that the plasmid would not be transmitted to other intestinal microflora in the environment. The transformant also survived in sterile tap and deionized water incubated at 25 C and 37 C in the laboratory for 30 days and was recovered from drinkers and birds in in vivo floor pen studies. In in vivo studies, E. coli AvGOB18 did not colonize the intestinal tract of broiler chicks when given as a single or multiple dose and did not reduce the Salmonella load in the broilers. But Salmonella typhimurium was reduced significantly in the intestinal tracts of broiler chickens when E. coli AvGOB18 was administered continually in the water supply.     

鸡体内减毒鼠伤寒沙门氏菌的繁殖和免疫反应

初步研究了cya和crp双基因突变减毒鼠伤寒沙门氏菌(Salmonella typhimurium)在鸡体内的繁殖和免疫反应。1、4或7日龄肉鸡分别经口感染10^8或10^9CFU减毒S．typhimurium X4550，接种后3—4周鸡体内特异性细胞和体液免疫达到最高峰。4日龄口服10^9CFu组免疫效果最佳，但1日龄高剂量组表现增重降低及免疫抑制。28日龄每鸡口服攻击10^10CFU强毒S．typhimurium 50333，各免疫组保护率为100％。同时免疫鸡还能全部或部分阻止沙门氏菌在肝脏和脾脏的繁殖。接种后病毒S．typhimurium在泄殖腔的检出时间为4周左右。     

Suppression of resistance to Salmonella typhimurium in young chickens inoculated with Corynebacterium parvum

The effect of Corynebacterium parvum on resistance to Salmonella typhimurium infection was evaluated in young chickens. One-day-old chickens were inoculated subcutaneously (SC) or intraperitoneally (IP) with 1.4 mg killed C. parvum and challenged by IP injection with 5.0 X 10(7) S. typhimurium 4 days later. Spleen and bursa of Fabricius weights were not altered in the C. parvum-inoculated chickens. A transient increase in thymus weight occurred 3 days after inoculation with C. parvum. Phytohemagglutinin-elicited cutaneous hypersensitivity was significantly suppressed in the C. parvum-inoculated chickens. Morbidity due to Salmonella infection increased significantly from 15% and 21% in the control groups to 43% and 46% in the chickens inoculated IP or SC with C. parvum. The results indicated that inoculation of 1-day-old chickens with C. parvum suppressed cell-mediated immune responsiveness and decreased resistance to peritoneal infection with S. typhimurium.     

泰乐加和呋喃它酮对大肠杆菌与沙门氏菌病的药效研究

本文对引进的抗菌兽药一泰乐加和呋喃它酮。在我国的条件下,用人工发病的方法进行了药效学研究。首先用体外药敏试验法筛选出三株对泰乐加和呋喃它酮敏感的致病菌,然后进行实验性药物预防治疗试验。试验结果表明。大肠杆菌O_2和O_(78)及沙门氏菌S_9对泰乐加和呋喃它酮高度敏感。呋喃它酮和泰乐加能显著降低沙门氏菌S_9及大肠杆菌O_2和O_(78)人工感染鸡群的发病率和死亡率(P<0.01),在鸡群发病时,用两种药物治疗,能有效地控制病情的发展和减少死亡率;粪便中接种菌的分离鉴定结果表明,两种药物均能显著降低排菌鸡的百分率。两药均不影响雏鸡的增重。实验性药物预防和治疗试验结果与药物临床试验结果相符。     

Lactobacilli counts in crop,ileum and caecum of growing broiler chickens fed on practical diets containing whole or dehulled sweet lupin (Lupinus angustifolius) seed meal

1. Four experiments with growing broiler chickens were carried out to study the effects of the inclusion in their diets of lupin (Lupinus angustifolius ) seed meal on E. coli and lactobacilli counts in crop, ileum and caeca at 3 or 4 weeks of age. 2. Diets were formulated to contain the same amounts of metabolisable energy (12.55 MJ/kg) and protein (210 g/kg). Raw whole (heat-untreated) or dehulled sweet (low in alkaloids) lupin seed meal (400 and 320 g/kg respectively) were used to prepare the lupin-based diets, whose protein content was completed with either defatted soyabean meal or casein. 3. Final body weight and food intake of chickens fed on whole lupin seed meal diets were lower than controls, but gain: food ratios were not different. However, birds given the diet with dehulled lupin seed meal had similar body weight, food intake and gain: food values as those of controls. 4. While E. coli counts were not affected, lactobacilli numbers were consistently increased compared to controls in all intestinal sections of chickens fed on the whole or dehulled lupin-based diets, irrespective of the age of the birds or the presence of soyabean meal or casein in the diet. The lactobacilli species isolated were: Lactobacillus fermentum, L. acidophilus, L. salivarius and L. brevis 5. The results suggest that the use of whole or dehulled sweet lupin seed meal in diets for growing broilers might enhance the growth of lactic acid-fermenting bacteria in the gut.     

嗜酸乳杆菌细胞壁提取物对致病性大肠杆菌粘附鸡肠纹状缘膜的影响

为研究嗜酸乳杆菌细胞壁提取物对致病性大肠杆菌(E.coli)粘附鸡肠纹状缘膜的影响,本实验以雏鸡小肠纹状缘膜为模型,以嗜酸乳杆菌和鸡致病性E.coli O78为研究对象,提取嗜酸乳杆菌表层蛋白、肽聚糖及E.coli O78菌毛,雏鸡小肠纹状缘膜,采用固相粘附试验和生物素标记法从分子间相互作用的关系评价了嗜酸乳杆菌细胞壁提取物对菌毛粘附的抑制作用,结果表明:表层蛋白和肽聚糖对菌毛粘附具有明显的抑制作用,呈浓度依赖性抑制菌毛与纹状缘膜的结合,具有竞争性拮抗作用,这主要是由空间占位造成的。肽聚糖的抑制作用相对较小。     

预防犊牛腹泻复合微生态制剂3株菌种的配比优化

试验旨在研究预防犊牛腹泻复合微生态制剂3株菌种的配比优化。通过研究嗜酸乳杆菌、布氏酵母菌、枯草芽孢杆菌不同浓度人工胃液、人工肠液、牛胆盐的耐受性及其对大肠杆菌、沙门氏菌、金黄色葡萄球菌的抑菌性,确定其生物学特性;以大肠杆菌K99为指示菌,研究3种益生菌不同配比对大肠杆菌K99的抑菌效果,以确定其最佳组合。结果表明:(1)3种益生菌在不同pH人工胃培养条件下都具有较好的耐受性,其中嗜酸乳杆菌、芽孢杆菌在pH为5时,存活率达到了118.75%、142.24%,布氏酵母菌对不同pH均表现成活率达到了100%以上。(2)3种益生菌在人工胃液中9 h存活率较高,与0 h的OD600相比,布氏酵母菌、枯草芽孢杆菌、嗜酸乳杆菌存活率分别为108.7%、129.73%、96.37%。(3)在含有不同浓度的牛胆盐培养基中,布氏酵母菌、嗜酸乳杆菌、枯草芽孢杆菌存活率较对照组的存活率最高为60.49%、85.1%、47.42%。(4)3株益生菌按照不同配比在培养12 h后,试验组第2、4、8组较对照组相比差异显著(P<0.05);培养24 h后,试验组第3、4、5、6较对照组差异显著(P<0.05),组间差异不显著(P>0.05);第8个处理组在培养12 h后对大肠杆菌K99的抑菌效果较好。综合分析,3株益生菌对人工胃液、人工肠液、牛胆盐具有较好的耐受性,并具对大肠杆菌K99、沙门氏菌、金黄色葡萄球菌等致病菌均有一定的抑菌特性。嗜酸乳杆菌、枯草芽孢杆菌、布氏酵母菌最佳的优化配比为3:3:1。     

嗜酸乳杆菌对黄羽肉鸡生长性能、肠道微生物及经济效益的影响

为探究饲料中嗜酸乳杆菌对肉鸡生产的效果,试验选取11日龄健康的黄羽肉鸡200羽,随机分为5组。分别为对照组(饲喂基础日粮),试验1、2、3、4组在基础日粮中分别添加5、10、15g/kg的嗜酸乳杆菌和150mg/kg的抗菌肽。结果表明:(1)与对照组相比,嗜酸乳杆菌组显著提高了肉鸡的日增重与采食量(P<0.05);但与抗菌肽组相比差异不显著(P>0.05)。(2)添加嗜酸乳杆菌15g/kg时,试验组中盲肠段内的双歧杆菌数量显著提高(P<0.05)。与对照组相比,4个试验组中的盲肠、回肠乳酸杆菌与双歧杆菌均有所提高,但只有试验3、4组呈现显著性差异(P<0.05),除此之外,各分组中回肠大肠杆菌数量无明显差异(P>0.05)。(3)与对照组相比,饲料中添加不同嗜酸乳杆菌能明显提高肉鸡生长性能和饲料利用率,增加经济效益。     

Effects of cage contamination with coccidia and salmonella on acute salmonellosis in young chickens

The effects of concurrent cage contamination with Salmonella typhimurium and Eimeria tenella on the establishment of salmonella infection in day-old chickens were investigated. Chickens were divided into five groups: uninfected recipient birds placed in a cage contaminated by donor birds infected with E. tenella and S. typhimurium; E. tenella-infected recipients placed in a cage contaminated by S. typhimurium-infected donors; uninfected recipients placed in a cage contaminated by S. typhimurium-infected donors; E. tenella-infected recipients placed in a cage contaminated by uninfected donors; and uninfected recipients placed in a cage contaminated by uninfected donors. Three identical trials were conducted. Recipient birds were necropsied 4, 7, and 11 days after caging. In the cage where donor birds infected with both organisms had been reared, S. typhimurium counts in feces and number of feces positive for S. typhimurium were significantly (P less than 0.05) greater than those in the other cages on days 0, 4, and 7 after caging. Moreover, in this cage, more chicks died, counts of S. typhimurium in cecal contents were greater, and more birds were positive for S. typhimurium than in the other groups. This suggests that S. typhimurium infection in day-old chickens is enhanced in cages contaminated with E. tenella and S. typhimurium compared with infection in cages contaminated with S. typhimurium alone.     

乳酸菌对仔犬生长性能、发病率、粪中大肠杆菌数量的影响

试验选用60只健康的德国牧羊犬仔犬,共计10窝,随机将每窝仔犬分成2组,试验组20-30日龄饲喂混有3.2 g乳酸菌素的奶粉,30日龄断乳后继续饲喂混有3.2 g乳酸菌的饲料,与对照组进行比较。以此来研究日粮中添加乳酸菌对仔犬生长性能、发病率、肠道菌群的影响。结果表明:在日粮中添加乳酸菌可提高断乳仔犬生长性能,增重明显,饲料利用率提高;降低仔犬发病率、死亡率(P<0.05)及缩短腹泻时间;降低粪便pH值约0.3-0.5单位,使断乳前厌氧菌群呈优势分布,同时增加乳酸菌的含量、减少大肠杆菌的含量(P<0.05)。