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1.
Experimental infection models are useful tools for understanding how Salmonella enteritidis is deposited in eggs and for testing potential strategies to control eggborne transmission of disease to humans. Oral inoculation of laying hens is presumed to provide the closest simulation of naturally occurring infections, but alternatives such as intravenous or aerosol inoculation have sometimes been recommended as options to induce higher incidences of egg contamination. The present study compared the frequency, level, and location of S. enteritidis deposition in egg contents after experimental inoculation by three different routes. In two replicate trials, specific-pathogen-free laying hens were infected with an S. enteritidis culture mixture prepared to optimize invasive behavior. Groups of hens received either an oral dose of 10(9) S. enteritidis, an aerosol dose of 10(9) S. enteritidis, or an intravenous dose of 10(5)-10(7) S. enteritidis. Oral inoculation led to the highest incidence of fecal shedding of S. enteritidis, whereas intravenous inoculation produced the highest specific antibody titers. Eggs laid during the first 21 days postinoculation were cultured to detect and enumerate S. enteritidis in the yolk and albumen. No significant differences were observed among the three inoculation routes in the frequencies of isolation of S. enteritidis from either yolk or albumen. For all three routes of administration, S. enteritidis was recovered more often from yolk (at frequencies ranging from 4% to 7%) than from albumen (0 to 2%). Over 73% of contaminated eggs harbored fewer than 1 colony-forming unit (CFU) of S. enteritidis per milliliter, and only 3% of such eggs contained more than 100 CFUs/ml. Significantly higher levels of S. enteritidis contaminants were associated with intravenous inoculation than with the other routes. No advantage of using aerosol or intravenous administration of S. enteritidis as an alternative to oral inoculation for inducing the production of contaminated eggs was evident in this study. 相似文献
2.
Laying hens were inoculated orally, intracloacally (IC), or intravenously (IV) with Salmonella enteritidis phage type 8 isolates from a human (E700-87) eggs (Y-8P2), or the ovary of a hen (27A). Oral or IV inoculation of 2 x 10(8) to 4 x 10(8) colony-forming units (CFU) of E700-87 caused depression, anorexia, reduced egg production, diarrhea, and some mortality. Lower doses resulted in milder clinical signs. S. enteritidis was cultured from the shells of a few eggs but not from egg contents. Fecal shedding persisted for up to 6 weeks in some birds. Isolate Y-8P2 (10(6) CFU) also caused anorexia, diarrhea, and a drop in egg production. Hens inoculated orally or IC were less severely affected than those inoculated IV. Fecal shedding was intermittent and lasted up to 18 days. Eggshells from the IC-inoculated birds had the highest rate of contamination, and S. enteritidis was isolated from the albumen of 11 and yolk of three of 726 eggs. Oral inoculation of 10(6) CFU of isolate 27A resulted in a bacteremic infection with seeding of the liver, spleen, peritoneum, ovule, and oviduct. However, the birds remained clinically normal with normal egg production. S. enteritidis was cultured from the yolk and albumen of a small number of eggs until 11 days postinfection. Antigen prepared from S. enteritidis detected antibody in more sera than did commercially available S. pullorum antigen in agglutination tests. 相似文献
3.
Yang B 《New Zealand veterinary journal》1992,40(3):117-119
Japanese quails were inoculated orally with 1 x 10(10) colony-forming units of Salmonella enteritidis phage type 4 isolated from chicks to obtain information concerning S. enteritidis infection and egg transmission. The inoculation resulted in a bacteraemic infection with seeding of the liver, spleen, intestine, peritoneum, ovule, ovary and oviduct. Some infected birds showed diarrhoea, ruffled feathers, depression, loss of appetite and death. However, most infected birds remained clinically normal with normal egg production. Salmonella enteritidis was isolated from the albumen of 7, yolk of 15, shell of 13, and shell membrane of 15 of 164 eggs. The experiment suggests that S. enteritidis phage type 4 is invasive for Japanese quails and the infected eggs laid by S. enteritidis infected quails are probably the result of transovarian infection. 相似文献
4.
Experimental infection models are valuable tools for understanding and preventing the deposition of Salmonella enteritidis inside eggs. Oral inoculation is believed to closely simulate naturally occurring S. enteritidis infections of chickens, but oral infection studies have often generated relatively low frequencies of egg contamination. The present study assessed whether repeated in vivo passage of an S. enteritidis strain could affect its ability to cause egg contamination in experimentally infected hens. The incidence of egg contamination was determined in groups of hens inoculated orally with either a phage type 13a S. enteritidis strain or derivatives of this parent strain that were obtained by three successive rounds of passage and reisolation from tissues of infected hens. Passaged S. enteritidis isolates recovered from ovaries and oviducts induced a significantly higher incidence of egg contamination (16.97%) than was attributed to the parent strain (8.27%). However, passaged S. enteritidis isolates recovered from livers and spleens were not associated with a significantly increased frequency of deposition in eggs. By either inducing or selecting for the expression of relevant microbial properties, passage of S. enteritidis through reproductive tissues of chickens may be useful for improving the efficiency at which experimental infection models produce egg contamination. 相似文献
5.
Internal contamination of eggs by Salmonella Enteritidis has been a significant source of human illness for several decades and is the focus of a recently proposed U.S. Food and Drug Administration regulatory plan. Salmonella Heidelberg has also been identified as an egg-transmitted human pathogen. The deposition of Salmonella strains inside eggs is apparently a consequence of reproductive tissue colonization in infected laying hens, but the relationship between colonization of specific regions of the reproductive tract and deposition in different locations within eggs is not well documented. In the present study, groups of laying hens were experimentally infected with large oral doses of Salmonella Heidelberg, Salmonella Enteritidis phage type 13a, or Salmonella Enteritidis phage type 14b. For all of these isolates, the overall frequency of ovarian colonization (34.0%) was significantly higher than the frequency of recovery from either the upper (22.9%) or lower (18.1%) regions of the oviduct. No significant differences were observed between the frequencies of Salmonella isolation from egg yolk and albumen (4.0% and 3.3%, respectively). Some significant differences between Salmonella isolates were observed in the frequency of recovery from eggs, but not in the frequency or patterns of recovery from reproductive organs. Accordingly, although the ability of these Salmonella isolates to colonize different regions of the reproductive tract in laying hens was reflected in deposition in both yolk and albumen, there was no indication that any specific affinity of individual isolates for particular regions of this tract produced distinctive patterns of deposition in eggs. 相似文献
6.
Detecting infected laying flocks is a vital part of many efforts to control egg-associated transmission of Salmonella enteritidis to humans. The relationship between the development of a specific antibody response in infected hens and the deposition of S. enteritidis in eggs is important for establishing the epidemiologic relevance of serologic testing methods. In two trials, laying hens were infected with large oral doses of phage types 13a and 14b isolates of S. enteritidis. Approximately 38% of all infected hens produced at least one contaminated egg, at an overall incidence of 5.2%, between 3 and 23 days postinoculation. As determined by enzyme-linked immunosorbent assay with an S. enteritidis flagellar antigen, 91.7% of inoculated hens produced specific serum antibodies. Although hens with very high antibody titers were associated with a significantly elevated frequency of egg contamination, a consistently direct relationship was not evident between the magnitude of the antibody responses of individual hens and the frequency at which they laid contaminated eggs. Accordingly, although serologic tests can be valuable screening tools for preliminary detection of S. enteritidis infections in poultry, the magnitude of the antibody responses detected in individual hens may not predict the overall risk of egg contamination associated with particular laying flocks. 相似文献
7.
The recent isolation of phage type 4 Salmonella enteritidis strains from poultry and humans in the United States has generated considerable concern because this phage type is predominant in both animals and humans in many other nations. Understanding whether the presence of these strains in poultry flocks poses an elevated threat to public health is a critical issue for developing effective disease control programs. The present study evaluated whether S. enteritidis strains of various phage types found in poultry in the United States (phage types 4, 8, and 13a) differed in their potential for horizontal transmission from experimentally infected chicks to uninoculated chicks housed in the same isolator units. Five days after two seeder chicks in each group of 12 were inoculated with oral doses of approximately 10(3) S. enteritidis cells at 8 days of age, ceca and livers were sampled from seeder chicks and from their contact-exposed penmates. On the basis of the detection of S. enteritidis in cecal samples, phage type 4 strains were transmitted horizontally at a significantly lower frequency than were strains of other phage types. Nevertheless, two of three phage type 4 strains evaluated were very highly invasive. 相似文献
8.
Production of Salmonella enteritidis-contaminated eggs by experimentally infected hens 总被引：9，自引：0，他引：9
Laying hens of three different ages were experimentally infected with a strain of Salmonella enteritidis by either oral inoculation or contact transmission. Total egg production was depressed in exposed hens of all three age groups. Persistent intestinal shedding was observed in a small number of hens. Eggs with contents contaminated by S. enteritidis were produced by exposed hens at a high frequency, but only during a fairly short period of time that extended through approximately 1 week postinoculation for older hens and through 2 weeks for younger hens. S. enteritidis was recovered from whole yolks and albumen of these eggs at similar frequencies, but not from the content of yolks. Eggs with contaminated shells were also produced, but at a lower frequency. Contaminated eggs were produced by orally inoculated and contact-exposed hens at similar frequencies. S. enteritidis was not isolated from the contents of eggs laid by hens infected with other S. enteritidis strains. 相似文献
9.
Internal contamination of eggs laid by hens infected with Salmonella enteritidis has been a prominent international public health issue since the mid-1980s. Considerable resources have been committed to detecting and controlling S. enteritidis infections in commercial laying flocks. Recently, the Centers for Disease Control and Prevention also reported a significant association between eggs or egg-containing foods and S. heidelberg infections in humans. The present study sought to determine whether several S. heidelberg isolates obtained from egg-associated human disease outbreaks were able to colonize reproductive tissues and be deposited inside eggs laid by experimentally infected hens in a manner similar to the previously documented behavior of S. enteritidis. In two trials, groups of laying hens were orally inoculated with large doses of four S. heidelberg strains and an S. enteritidis strain that consistently caused egg contamination in previous studies. All five Salmonella strains (of both serotypes) colonized the intestinal tracts and invaded the livers, spleens, ovaries, and oviducts of inoculated hens, with no significant differences observed between the strains for any of these parameters. All four S. heidelberg strains were recovered from the interior liquid contents of eggs laid by infected hens, although at lower frequencies (between 1.1% and 4.5%) than the S. enteritidis strain (7.0%). 相似文献
10.
The level of Salmonella enteritidis contamination in Zambian table eggs and ready market chicken carcasses was studied. Nine of the 240 (3.8%) pooled samples of table eggs and 18 of 382 (4.7%) chicken carcasses were contaminated with S. enteritidis. All the isolates from the table eggs belonged to the enteropathogenic invasive phage type 4, whereas seven isolates from the chicken carcasses belonged to phage type 4, three were phage type 7, and eight were untypable (rough type). All the isolates were sensitive to gentamycin, ampicillin, tetracycline, cotrimoxazole, amoxycillin, furazolidone, and chloramphenicol. 相似文献
11.
Salmonella enteritidis and other Salmonella in laying hens and eggs from flocks with Salmonella in their environment. 总被引：2，自引：1，他引：1 
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下载免费PDF全文 C Poppe R P Johnson C M Forsberg R J Irwin 《Canadian journal of veterinary research》1992,56(3):226-232
Seven Canadian layer flocks with Salmonella enteritidis in their environment were investigated to determine the numbers of hens infected with S. enteritidis, the localization of S. enteritidis in organs of infected hens and the numbers of S. enteritidis-infected eggs produced by two affected flocks. By a microagglutination test (MAT) using S. pullorum antigens, these flocks had more seropositive hens (mean 51.9 +/- 16.9%) than two Salmonella-free flocks (mean 13.0 +/- 4.2%). Culture of tissues of 580 hens (433 seropositive) from the seven flocks detected 26 (4.5%) S. enteritidis-infected hens from two flocks. In one flock, 2/150 hens were infected with S. enteritidis phage type (PT) 8, which was confined to the ceca, and no Salmonella spp. were isolated from 2520 eggs (one day's lay). In the second flock, where 24/150 hens were infected with S. enteritidis PT13, extraintestinal infection was found in nine hens and involved the ovaries and/or oviduct in two hens. Salmonella enteritidis PT13 was isolated from one sample of egg contents and from one sample of cracked shells from among 14,040 eggs (one day's lay) from this flock. The overall prevalence of S. enteritidis-contaminated eggs from the two flocks with infected hens was less than 0.06%. Other Salmonella spp. isolated were S. heidelberg from 58 hens (10%), and S. hadar, S. mbandaka and S. typhimurium from one hen (0.2%) each. The MAT with antigens of S. pullorum had a sensitivity of 81% and a specificity of 24% for detecting S. enteritidis-infected hens.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
12.
To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment. 相似文献
13.
1. Effects of two housing systems (cages vs outdoor) on external and internal egg characteristics were investigated. 2. In total 785 eggs from three different lines in cages and 268 eggs from outdoor-housed layers were examined for egg weight, albumen, yolk and shell content, albumen height and pH, and albumen and yolk dry matter content. 3. Interactions between layer age and housing systems were found for egg weight, eggshell content, albumen height, albumen pH, and dry matter content of the albumen and yolk. This was mainly due to the greater variation with age in the outdoor layers, compared to the caged layers. 4. Irrespective of age eggs from outdoor layers were relatively broader than eggs from the caged layers. Yolk colour was considerably darker in the outdoor group (11.0 vs 9.3). 5. We concluded that it is more difficult to maintain constant external and internal egg quality in an outdoor housing system than in a battery cage system. Factors that determine the greater fluctuations in internal egg quality need to be investigated. 相似文献
14.
[目的]研究鸡蛋暗斑对蛋品质及其抗氧化能力的影响。[方法]从饲喂同种日粮、饲养环境相同、同日龄褐壳蛋鸡同一批次所产的褐壳蛋中,用灯光照射法挑选出24枚典型正常蛋、24枚典型暗斑蛋进行试验,并分别对正常蛋和暗斑蛋进行蛋品质、蛋黄抗氧化指标的测定及比较。[结果]蛋品质比较:暗斑蛋与正常蛋相比,其蛋形指数、蛋壳强度、蛋重、哈氏单位、蛋白高度、鸡蛋等级、蛋黄颜色、蛋黄重、蛋壳重、蛋清重、蛋壳厚度、蛋黄比重、蛋壳比重、蛋清比重均差异不显著(P>0.05);暗斑蛋蛋壳颜色极显著深于正常蛋(P<0.01)。抗氧化指标比较:暗斑蛋蛋黄的总抗氧化能力(T-AOC)显著低于正常蛋蛋黄的总抗氧化能力(P<0.05),暗斑蛋蛋黄的丙二醛(MDA)含量与正常蛋蛋黄的丙二醛含量相比差异不显著(P>0.05)。[结论]与正常蛋相比,暗斑蛋的蛋壳颜色较深,总抗氧化能力较差。 相似文献
15.
Detection of antibody to Salmonella enteritidis and S typhimurium in the yolk of hens' eggs 总被引：2，自引：0，他引：2
Enzyme-linked immunosorbent assays (ELISAs) have been developed to detect IgG antibodies to Salmonella enteritidis and S typhimurium in the yolk of hens' eggs. Better discrimination and more consistent results were obtained between eggs from experimentally infected and uninfected hens by using saline-dilution of yolk rather than chloroform extraction. Threshold absorbance values were determined in three salmonella-free flocks, and on the basis of these results ELISA optical density values greater than 0.25 were considered to be positive for antibodies to salmonella. Four flocks with a history of salmonella infection were examined; three contained birds which were seropositive for S enteritidis by ELISA and from which S enteritidis was isolated, and a large proportion of eggs from these birds contained antibody to S enteritidis. Eggs from the fourth flock had no detectable antibody, although serum antibody was detected in some birds. No salmonellae were isolated from the yolks of the eggs from any of the four flocks. 相似文献
16.
本试验分析了不同贮存温度和时间对鸽蛋新鲜度、组分、蛋品质及蛋白透明度的影响,寻求鸽蛋贮存的最佳条件,并探索不同贮存条件下鸽蛋蛋白透明度的变化规律,为实际生产中鸽蛋合理贮存和出售提供理论依据。以1~2岁公母配对白羽王鸽为试验对象,采用3（低温、中温、高温）×4（1、2、3、4周）因子交叉完全随机设计,试验开始后每周随机采集90枚鸽蛋,分别放置在3种不同温度条件下,每组30枚,分别持续1、2、3、4周,而后对鸽蛋进行新鲜度、组分、蛋品质及蛋白透明度的测定分析。结果显示,低温条件下,鸽蛋放置4周未出现散黄和可见霉变现象。高温和中温条件下,鸽蛋只可放置1周不变质。随着时间的延长和温度的升高,鸽蛋的失重率显著上升（P<0.05）。时间对蛋壳率、蛋白率及蛋黄率均有显著影响（P<0.05）,但温度对其无显著影响（P>0.05）。不同贮存温度和时间对鸽蛋的蛋白高度和蛋黄颜色均有显著影响（P<0.05）,即随着时间的延长和温度的升高,鸽蛋的蛋白高度呈下降趋势,蛋黄颜色变深。不同贮存温度和时间对煮熟的鸽蛋蛋白L*、a*和b*值均有显著影响（P<0.05）;中温贮存透明鸽蛋所占比例最高。综上所述,鸽蛋贮运和贩售需在冷藏条件下进行。在低温冷藏条件下,鸽蛋可贮存4周以上。在中温条件下（20℃左右）保存,有利于提高鸽蛋蛋白透明度。 相似文献
17.
不同周龄母鸡鸡蛋及不同蛋壳质地鸡蛋的蛋品质比较 总被引：1，自引：0，他引：1
本文比较了同一品种不同周龄(26、40周龄和64周龄)母鸡所产蛋的蛋壳品质和蛋品质,包括蛋重、蛋壳相对重、蛋形指数、蛋壳强度、蛋壳厚度、蛋黄颜色、蛋黄指数、蛋黄比率、哈氏单位、蛋清pH值。之后,还比较了该鸡种不同蛋壳质地鸡蛋(正常蛋和砂壳蛋)之间上述指标的差异。结果表明:在不同周龄母鸡所产蛋之间,蛋重、蛋黄指数、蛋黄比率、哈氏单位等均存在显著差异(p<0.05),而蛋壳厚度之间差异不显著(p>0.05)。此外,蛋重、蛋形指数、蛋黄颜色、蛋黄比率随着母鸡周龄的增加呈上升趋势,而蛋壳强度、蛋壳相对重、哈氏单位、蛋黄指数、蛋清pH值呈下降趋势。最后,蛋壳质地不同的鸡蛋(正常蛋与砂壳蛋)之间,蛋重、蛋壳相对重、蛋壳强度、蛋清pH值之间存在极显著差异(p<0.01),而其他参数之间差异不显著(p>0.05)。 相似文献
18.
1. Eggs from a layer-type breeder flock (Baladi, King Saud University) between 50 and 63 weeks of age were used in three trials to study the effects of electrical field (EF) during incubation on albumen and yolk heights, incubation temperature, egg weight loss and hatchability traits. The effects of egg size and eggshell characteristics on hatchability traits of eggs incubated under EF were investigated. 2. Eggs were weighed and graded into three weight classes (small, medium, and large). The physical dimensions, eggshell characteristics, and conductance of eggs were examined. The incubator was divided into two compartments for the control and EF treatments. Two aluminium plates were fitted on the inside walls of the EF compartment, face to face, and connected to a step up electric transformer. Eggs were exposed constantly to the EF during the first 18 d of incubation at the level of 30 kV/m, 60 Hz. 3. Egg size influenced the physical dimensions and eggshell characteristics of eggs. Large eggs had higher egg weight, egg surface area, egg volume, eggshell conductance, and eggshell weight and lower yolk weight percentage than medium or small size eggs. Small eggs had lower egg length and higher egg density than large or medium size eggs. Large eggs had higher eggshell thickness than small size eggs. 4. EF incubation of eggs raised incubation temperature by 0.06 degrees C, and increased the percentage of egg weight loss, hatchability, and weight of hatching chicks and reduced the early embryo deaths, and length of incubation by approximately 9.8, 19.6, 1.7, 62.1 and 2.1%, respectively. 5. There was no significant difference between the two incubation treatments in the heights of albumen and yolk of incubated eggs, percentages of late embryo deaths, and pips with live and dead embryos. Hatchability traits were not significantly influenced by egg size. 6. It was concluded that EF incubation of eggs increased hatchability, chick-hatching weight, and reduced the length of incubation of Baladi eggs. Differences in the physical dimensions and eggshell characteristics of eggs did not influence hatchability traits of eggs under EF incubation. 相似文献
19.
Differences among six Salmonella serovars in abilities to colonize reproductive organs and to contaminate eggs in laying hens 总被引：3，自引：0，他引：3
The abilities of Salmonella serovars to colonize the reproductive organs of chickens and to contaminate eggs were compared. Mature laying hens were inoculated intravenously with 10(5) colony-forming units of Salmonella enteritidis, Salmonella typhimurium, Salmonella infantis, Salmonella hadar, Salmonella heidelberg, or Salmonella montevideo to cause the systemic infection. Salmonella enteritidis was recovered from three yolks of the laid eggs (7.0%), suggesting egg contamination from the transovarian transmission of S. enteritidis. The liver, spleen, and cecum were colonized by each serovar similarly at 4 or 7 days postinoculation (PI), whereas the ovary and preovulatory follicles were colonized by S. enteritidis with significantly (P < 0.05) higher levels than by the other serovars at 4 and 7 days PI. Salmonella enteritidis was recovered from the cloaca and vagina at 2, 4, and 7 days PI and from the other portions of the oviduct at 4 and 7 days PI. In addition, S. enteritidis had been persistent in the peripheral blood for 7 days PI. These results suggest that S. enteritidis is the predominant serovar to colonize the reproductive organs of mature laying hens among six serovars used in this study, reflecting the field situatibn in which the predominant outbreaks of human salmonellosis were caused by S. enteritidis-contaminated eggs recently. The ability of S. enteritidis to colonize the reproductive organs may be one of the reasons that egg contamination with S. enteritidis has increased. 相似文献
20.
Kinde H Castellan DM Kass PH Ardans A Cutler G Breitmeyer RE Bell DD Ernst RA Kerr DC Little HE Willoughby D Riemann HP Snowdon JA Kuney DR 《Avian diseases》2004,48(3):590-594
Between the summer of 1998 and the winter of 2000, Salmonella analysis was performed on 2128 single and 532 pooled manure drag swabs obtained from 133 California commercial egg laying farms. The isolation of Salmonella from all rows and from all flocks using single or pooled swabs was 80% and 92%, respectively. Hence, there was no statistical difference between single vs. pooled swabs in terms of identifying Salmonella on a row or flock basis. A total of 14 serogroups comprising 44 serotypes were isolated from 123 of 133 farms. When the top 10 serotypes were considered, there was no significant difference in the range of serotypes isolated by the two culturing methods. The overall S. enteritidis prevalence for California flocks was 10.5% (14/133). The overall row prevalence for S. enteritidis for all the farms was 1.1% (24/2128), and the overall pool prevalence was 2.4% (13/532). Sixty percent (12/20) of the S. enteritidis isolates from the positive farms were phage type 4, and 40% (8/20) represented five other phage types (1, 6B, 7, 8, and 28). 相似文献