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1.
In the chicken, maternal antibodies are transferred into the egg and subsequently transported into the developing embryo. IgG (called IgY) is the primary immunoglobulin isotype of the egg yolk. Their level in serum depends on the correct function of immunological system in laying hens. Many factors have a direct or indirect influence on antibody level in fowl. One of them is a commonly used antibiotic, but its influence on avian immune system is still unknown. The objective of the study was to determine the effect of enrofloxacin and chloramphenicol on the level of IgY antibody in serum and egg yolk after immunostimulation of hens with living cells of Salmonella enterica subsp. enterica serovar Enteritidis and lipopolisaccharide. Forty adult egg-laying Arbor Acres and Isa 215 hens (32 and 50 weeks old) from the reproductive flocks and 1640 of their eggs were used for the investigation. No clinical symptoms of any diseases were observed in birds during the entire breeding period. Additionally the birds were checked as free from Salmonella spp. in the beginning of the experiment. The birds were divided into 6 experimental and 2 control groups (5 birds in one group). The hens in the experimental groups were immunized with S. Enteritidis antigens: living bacteria and lipopolisaccharide and treated with enrofloxacin or chloramphenicol. Antibiotics were administered in drinking water for 10 days (from 3rd to 13th day of experiment). To indicate anti-S. Enteritidis, antibodies in sera and egg yolk were used indirectly on ELISA based on lipopolisaccharide from S. Enteritidis. As conjugate these were applied anti-chicken IgY with horseradish peroxidase and ABTS with H2O2 as obtained. Additionally, to detect antibody in serum, a rapid slide test was used with Pullognost and Enterognost standard antigens made in the laboratory. The study revealed that both antibiotics tested decreased the level of specific IgY in laying hens immunized with living bacteria and lipopolisaccharide. It seems that antibiotics have a suppressive effect on the immunological system. The strongest immunosuppressive effect was exerted by chloramphenicol.  相似文献   

2.
Pang Y  Wang H  Li Z  Piao J  Piao J  Chi Y  Jin J  Liu Q  Li W 《Avian diseases》2012,56(2):347-353
In order to generate Salmonella enterica serovar Enteritidis fimbriae antigens (rSEF21), the intact region encoding SEF21 was amplified from Salmonella Enteritidis by PCR and subcloned into a prokaryotic expression vector pET-28a(+) to yield pET-28a(+)-SEF21. The rSEF21 protein was highly expressed and purified by nickel affinity chromatography. Liposomeassociated rSEF21 was prepared for oral immunization to seek protective efficacy for intestinal infection with Salmonella Enteritidis. Evidence of IgA and IgG responses were found in the intestinal tracts and in the sera of a group of chickens immunized. Two weeks after the booster immunization, the chickens were challenged orally with 2 x 10(6) colony-forming units of live Salmonella Enteritidis, and fecal samples were examined for bacterial excretion from the intestinal tract. Significantly less fecal excretion of bacteria was observed in immunized chickens for 4 wk after challenge. The numbers of bacteria in the intestinal contents (cecum and rectum) were also significantly lower in immunized chickens than in unimmunized controls. Therefore, oral immunization with liposome-associated rSEF21 elicits both systemic and mucosal antibody responses, leading to a reduction in bacterial colonization in the intestinal tract and excretion of Salmonella Enteritidis in the feces.  相似文献   

3.
This experiment was conducted to ascertain whether the growth of Salmonella Enteritidis (SE) or Salmonella Typhimurium (ST) would be suppressed in the presence of antibodies contained in egg yolks. Specific pathogen-free chickens (102 days of age) were subcutaneously immunized with oil-adjuvanted bacterin of SE or ST, twice within a four-week interval. During 160 to 170 days of age, eggs were collected, the yolks were removed and mixed with an equal volume of physiological buffered saline, inoculated with ten colony forming units (CFU) of SE or ST, and incubated at 37 degrees C or 20 degrees C for 23 hr. The growth of organisms in each yolk solution was examined. The egg yolk derived from non-immunized hens was examined in the same manner as the controls. There was no difference in the growth titer between the antibody-positive yolk and the negative yolk. The result suggests that the antibodies in the yolk do not influence the growth of each organism, even if the hens are highly immunized.  相似文献   

4.
Salmonella Enteritidis in contaminated eggs is a public health hazard that may cause hospitalization or death in the elderly, infants, and individuals with impaired immune systems. Prevention of Salmonella Enteritidis infection of laying hens is an essential first step in reducing Salmonella Enteritidis outbreaks in humans. Multiple interventions at several stages during egg production can combine to reduce numbers of infected chickens and keep egg contamination to low levels. Every effort should be made to exclude Salmonella Enteritidis from egg production premises by implementing effective biosecurity measures, stocking the farm with Salmonella Enteritidis-free replacement pullets, controlling rodent and insect vectors, and denying wild birds and pets access to chicken houses. Diligent cleaning and disinfection of chicken houses before introduction of a new flock will minimize environmental exposure and indirect horizontal transmission of multiple pathogens, including Salmonella Enteritidis. Increased resistance of chickens to intestinal colonization by Salmonella Enteritidis can be attained by the use of probiotics, prebiotics, and synbiotics. Laying hens should be immunized with live and killed vaccines to stimulate mucosal and systemic immunity and reduce the prevalence of Salmonella Enteritidis-contaminated eggs. Shell eggs should be refrigerated as soon as possible after laying to keep Salmonella Enteritidis cells at low levels in any contaminated eggs. Comprehensive Salmonella Enteritidis-control programs have proven to be successful in reducing the incidence of Salmonella Enteritidis infections in both egg-laying flocks and humans.  相似文献   

5.
A comparison on the prevalence of Salmonella infection in layer hens from commercial layer farms with high and low rodent densities was investigated. Out of 280 laying hens sampled from three commercial layer farms with high rodent densities, Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Enteritidis) was isolated from 20 (7.14%) hens and Salmonella enterica subsp. enterica serovar Infantis (Salmonella Infantis) from three (1.07%) hens. In contrast, layer hens sampled from four commercial layer farms with low rodent densities were negative for any salmonellae. Significant differences (P < 0.05) in the isolation rates of Salmonella from various organs of infected layer hens were also noted. For Salmonella Enteritidis, liver (55.0%) and the oviduct (55.0%) had the highest isolation rates while all Salmonella Infantis isolates were from the oviduct. Pulsed field gel electrophoresis (PFGE) analysis of BlnI-digested chromosomal DNA of Salmonella Enteritidis isolated from layer hens and rodents showed similar patterns. PFGE analysis of Salmonella Infantis isolated from layer hens, rodents, eggs, and the environment yielded identical patterns. In this study, the significantly higher prevalence rate (P < 0.05) of Salmonella Enteritidis and Salmonella Infantis in layer hens from high rodent density farms could be attributed to the high rodent population density. The persistent Salmonella Enteritidis and Salmonella Infantis infection inside layer houses may have been amplified by the increasing numbers in the rodent population over the years, which increased the opportunity for environment-rodent-chicken interaction and the transmission of salmonellae to chickens. Monitoring of salmonellae from rodents inside poultry premises is recommended to be an effective additional tool in the assessment of the Salmonella status of layer flocks.  相似文献   

6.
Salmonella enterica serovar Enteritidis (S. Enteritidis) is one of the most prevalent causes for human gastroenteritis and is by far the predominant Salmonella serovar among human cases, followed by Salmonella Typhimurium. Contaminated eggs produced by infected laying hens are thought to be the main source of human infection with S. Enteritidis throughout the world. Although previous studies have looked at the proportion of infected eggs from infected flocks, there is still uncertainty over the rate at which infected birds produce contaminated eggs. The aim of this study was to estimate the rate at which infected birds produce contaminated egg shells and egg contents. Data were collected from two studies, consisting of 15 and 20 flocks, respectively. Faecal and environmental sampling and testing of ovaries/caeca from laying hens were carried out in parallel with (i) for the first study, testing 300 individual eggs, contents and shells together and (ii) for the second study, testing 4000 eggs in pools of six, with shells and contents tested separately. Bayesian methods were used to estimate the within‐flock prevalence of infection from the faecal and hen post‐mortem data, and this was related to the proportion of positive eggs. Results indicated a linear relationship between the rate of contamination of egg contents and the prevalence of infected chickens, but a nonlinear (quadratic) relationship between infection prevalence and the rate of egg shell contamination, with egg shell contamination occurring at a much higher rate than that of egg contents. There was also a significant difference in the rate of egg contamination between serovars, with S. Enteritidis causing a higher rate of contamination of egg contents and a lower rate of contamination of egg shells compared to non‐S. Enteritidis serovars. These results will be useful for risk assessments of human exposure to Salmonella‐contaminated eggs.  相似文献   

7.
As laying hens age, egg production and quality decreases. Egg producers can impose an induced molt on older hens that results in increased egg productivity and decreased hen mortality compared with non-molted hens of the same age. This review discusses the effect of induced molting by feed removal on immune parameters, Salmonella enterica serovar Enteritidis (SE) invasion and subsequent production of SE-contaminated eggs. Experimental oral infections with SE show molted hens are more susceptible to SE infection and produce more SE-contaminated eggs in the first few weeks post-molt compared with pre-molt egg production. In addition, it appears that molted hens are more likely to disseminate SE into their environment. Molted hens are more susceptible to SE infection by contact exposure to experimentally infected hens; thus, transmission of SE among molted hens could be more rapid than non-molted birds. Histological examination of the gastrointestinal tracts of molted SE-infected hens revealed more frequent and severe intestinal mucosal lesions compared with non-molted SE-infected hens. These data suggest that induced molting by feed deprivation alters the normal asymptomatic host-pathogen relationship. Published data suggest the highest proportion of SE-positive eggs is produced within 1-5 weeks post-molt and decreases sharply by 6-10 weeks and dissipates to the background level for non-molted hens by 11-20 weeks. Appropriate treatment measures of eggs produced in the fist 5 weeks post-molting may decrease the risk of foodborne infections to humans.  相似文献   

8.
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9.
ABSTRACT: Human cases of bacterial gastro-enteritis are often caused by the consumption of eggs contaminated with Salmonella species, mainly Salmonella enterica serovar Enteriditis (Salmonella Enteritidis). To reduce human exposure, in several countries worldwide surveillance programmes are implemented to detect colonized layer flocks. The sampling schemes are based on the within-flock prevalence, and, as this changes over time, knowledge of the within-flock dynamics of Salmonella Enteritidis is required. Transmission of Salmonella Enteritidis has been quantified in pairs of layers, but the question is whether the dynamics in pairs is comparable to transmission in large groups, which are more representative for commercial layer flocks. The aim of this study was to compare results of transmission experiments between pairs and groups of laying hens. Experimental groups of either 2 or 200 hens were housed at similar densities, and 1 or 4 hens were inoculated with Salmonella Enteritidis, respectively. Excretion was monitored by regularly testing of fecal samples for the presence of Salmonella Enteritidis. Using mathematical modeling, the group experiments were simulated with transmission parameter estimates from the pairwise experiments. Transmission of the bacteria did not differ significantly between pairs or groups. This finding suggests that the transmission parameter estimates from small-scale experiments might be extrapolated to the field situation.  相似文献   

10.
In the last 2 decades, the prevalence of Salmonella enterica serotype Enteritidis (Salmonella Enteritidis) has dramatically increased worldwide, becoming the leading cause of food-borne illnesses and an important public health issue. Many studies have suggested the role of the SEF14 fimbrial protein in the adhesion of Salmonella Enteritidis to the host. In the present study, the sefA gene, which encodes the main subunit of the SEF14 fimbrial protein, was cloned into a temperature-sensitive expression vector and transformed into a nonpathogenic, avirulent strain of Escherichia coli. The recombinant strain was used as a vaccine to elicit specific immune response against the SefA protein of Salmonella Enteritidis in 1-day-old chickens. The recombinant strain was reisolated from the intestines of treated birds for up to 21 days posttreatment, demonstrating its ability to colonize the intestinal tracts of 1-day-old chickens. In addition, immunoglobulin A (IgA) against the SefA protein was detected in intestinal secretions from treated birds at 7 days posttreatment and in bile samples from 14 to 21 days posttreatment by enzyme-linked immunosorbent assay. Nontreated birds did not show any evidence of intestinal colonization by the recombinant strain or anti-SefA IgA response in their bile or intestinal secretions. Preliminary evaluation of the recombinant strain showed a potential use of this strain to elicit protection against Salmonella Enteritidis infection in chickens. Further experiments are needed to study the ability of the recombinant strain to protect birds against Salmonella Enteritidis colonization.  相似文献   

11.
To evaluate the efficacy of a novel attenuated Salmonella Enteritidis (△lon△cpxR) vaccine candidate (JOL919), chickens were immunized through oral and intramuscular routes to reduce egg contamination against S. Enteritidis challenge. Birds were orally immunized with JOL919 on the first day of life and were subsequently boosted in the 6th and 16th weeks through oral (group B) or intramuscular (group C) route, while control birds were unimmunized (group A). The chickens of all groups were challenged intravenously with the virulent S. Enteritidis strain in the 24th week. The immunized groups B and C showed significantly higher plasma IgG and intestinal secretory IgA levels as compared to those of the control group. The lymphocyte proliferation response and CD45+CD3+ T‐cell number in the peripheral blood of the groups B and C were significantly increased. In addition, the egg contamination rates were significantly lower in the group B (0%, 10.7% and 0%) and the group C (3.6%, 14.3% and 3.6%) as compared to the group A (28.6%, 42.8% and 28.6%) in the 1st, 2nd and 3rd weeks post‐challenge. All animals in the groups B and C showed lower organ lesion scores in the liver and spleen and lower bacterial counts in the liver, spleen and ovary at the 3rd week post‐challenge. These results indicate that this vaccine candidate can be an efficient tool for prevention of Salmonella infections by inducing protective humoral and cellular immune responses. In addition, this vaccine did not prevent egg contamination, but did appear to reduce incidence. Booster immunizations, especially via oral administration route, showed an efficient protection against internal egg contamination with S. Enteritidis.  相似文献   

12.
Levels of Salmonella enterica subsp. enterica serovar Enteritidis infection and serum S. Enteritidis antibodies after experimental S. Enteritidis challenge and feed withdrawal were investigated in S. Enteritidis-vaccinated and unvaccinated hens. The results were used to determine whether formalin-inactivated S. Enteritidis vaccination can protect layer hens from S. Enteritidis challenge during feed withdrawal periods. S. Enteritidis infection rates were evaluated from cloacal swabs, eggs and organs. Serum antibody titers to deflagellated S. Enteritidis whole cells (DEWC) and S. Enteritidis FliC-specific 9-kDa polypeptide (SEp 9) were examined by commercial ELISA kits. Cloacal S. Enteritidis recovery rates were lower in the vaccinated than unvaccinated group. Recovery rates of S. Enteritidis from samples increased after feed withdrawal and decreased after re-introduction of feed. S. Enteritidis counts in cloacal swabs were lower in the vaccinated than in the unvaccinated group (P<0.05). More S. Enteritidis-positive eggs were detected from the unvaccinated group. Before S. Enteritidis challenge, the DEWC ELISA titer of the vaccinated group was higher (P<0.05) than the unvaccinated group; subsequently, the S. Enteritidis DEWC ELISA titers of both groups increased gradually. In contrast, only the vaccinated group elicited high SEp-9 antibody titer during post-challenge and feed withdrawal. Additionally, vaccinated hens yielded negative S. Enteritidis isolation rates from egg contents. There is a correlation between negative S. Enteritidis isolation rates and high SEp 9 titers in vaccinated layer hens challenged with S. Enteritidis and subjected to feed withdrawal regimens. These findings suggest the S. Enteritidis vaccination of pullets may protect against S. Enteritidis infection during forced molting and that SEp 9 titer could be a potential indicator of antibody protection against S. Enteritidis infection. The potential of the SEp 9 peptide as an antigen for S. Enteritidis vaccination in the future is worth noting.  相似文献   

13.
Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) titres to BC14 virus and increasing numbers of birds with HI titres were observed from 3 weeks to 15 weeks of age. Sixty-one per cent of the hens and 77 per cent of the cocks had 2 log HI BC14 virus titres exceeding 4 at an age of 15 weeks. Some birds which han been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus. EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the results of a production drop in the hens showing serconversion at 27 or 28 weeks of age. In this group of fowl vertically infected with EDs'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.  相似文献   

14.
Using a deletion mutant in the regulator of SPI-2, ssrA, we investigated the role of SPI-2 in invasion, intestinal colonization and reproductive tract infection of chickens by Salmonella Enteritidis. The ssrA mutant was fully invasive in phagocytic and non-phagocytic cells but failed to persist within chicken macrophages. The ability of Salmonella Enteritidis to cause disease in orally infected 1-day-old chicks was not altered when ssrA was deleted. Furthermore, caecal colonization was not affected, while spleen and liver showed reduced colonization. Following intra-peritoneal and intravenous infection of 1-day-old chicks, internal organ colonization was strongly reduced. After intravenous inoculation in adult laying hens bacterial numbers of the ssrA mutant were significantly lower in oviducts and ovaries as compared to the wild type strain. The chickens showed less reproductive tract lesions and the recovery of egg production were faster compared to the wild type strain infected chickens. These findings indicate that the SPI-2 regulator ssrA promotes reproductive tract colonization, but is not essential for intestinal colonization of chickens with the host non-specific serotype Enteritidis.  相似文献   

15.
Gast RK  Guraya R  Guard J  Holt PS 《Avian diseases》2011,55(2):243-247
Contamination of eggs by Salmonella Enteritidis has been a prominent cause of human illness for several decades and is the focus of a recently implemented national regulatory plan for egg-producing flocks in the United States. Salmonella Heidelberg has also been identified as an egg-transmitted pathogen. The deposition of Salmonella strains inside eggs is a consequence of reproductive tract colonization in infected laying hens, but prior research has not determined the relationship between the numbers of Salmonella that colonize reproductive organs and the associated frequency of egg contamination. In the present study, groups of laying hens in two trials were experimentally infected with large oral doses of strains of Salmonella Enteritidis (phage type 13a), Salmonella Heidelberg, or Salmonella Hadar. Reproductive tissues of selected hens were cultured to detect and enumerate Salmonella at 5 days postinoculation, and the interior contents of eggs laid between 6 and 25 days postinoculation were tested for contamination. Significantly more internally contaminated eggs were laid by hens infected with Salmonella Enteritidis (3.58%) than with strains of either Salmonella Heidelberg (0.47%) or Salmonella Hadar (0%). However, no significant differences were observed between Salmonella strains in either isolation frequency or the number of colony-forming units (CFU) isolated from ovaries or oviducts. Salmonella isolation frequencies ranged from 20.8% to 41.7% for ovaries and from 8.3% to 33.3% for oviducts. Mean Salmonella colonization levels ranged from 0.10 to 0.51 log CFU/g for ovaries and from 0.25 to 0.46 log CFU/g for oviducts. Although parallel rank-orders were observed for Salmonella enumeration (in both ovaries and oviducts) and egg contamination frequency, a statistically significant relationship could not be established between these two parameters of infection.  相似文献   

16.
Egg contamination by Salmonella Enteritidis has remained a significant public health problem for nearly two decades, and Salmonella Heidelberg has also been recently implicated in egg-transmitted human illness. Colonization of the intestinal tract is a necessary precursor to the invasion of reproductive organs and subsequent deposition inside eggs laid by infected hens, but the relationship between the persistence of Salmonella in the intestinal tract and the likelihood of egg contamination has been uncertain. In this study, groups of laying hens were inoculated with large oral doses of strains of Salmonella Enteritidis and Salmonella Heidelberg, including variants of the original parent strains that had been reisolated from eggs laid by infected hens in a prior study. The shedding of Salmonella in voided feces was monitored for 6 wk postinoculation, and all eggs laid by infected hens between 5 and 22 days postinoculation were cultured for Salmonella in their contents. The mean duration of fecal shedding was significantly longer for the previously passaged Salmonella strains (26.7 days) than for the original parent strains (17.5 days), and the passaged strains caused a significantly higher frequency of egg contamination (6.4%) than did the parent strains (3.3%). However, the duration of fecal shedding and the frequency of egg contamination were not correlated for any of the Salmonella Enteritidis or Salmonella Heidelberg strains.  相似文献   

17.
Summary

Following EDS'76 virus (BC14 virus) infection of breeder chickens by the conjunctival route, vertical transmission occurred in the first week after infection. In the progeny which had been infected with EDS'76 virus by the vertical route, increasing haemagglutination inhibiting (HI) litres to BC14 virus and increasing numbers of birds with HI litres were observed from 3 weeks to 15 weeks of age. Sixty‐one per cent of the hens and 77 per cent of the cocks had 2log HI BC14 virus litres exceeding 4 at an age of 15 weeks.

Some birds which had been serologically negative throughout the rearing period, seroconverted between 25 and 28 weeks of age. This phenomenon occurred in hens as well as in cocks. Simulation of stress twice during the laying period by injection of corticosteroid hormone did not increase the number of birds serologically positive to EDS'76 virus.

EDS'76 was observed in the group of hens that was vertically infected, since egg production was significantly depressed between 28 and 34 weeks of age. Probably this was mainly the result of a production drop in the hens showing seroconversion at 27 or 28 weeks of age.

In the group of fowl vertically infected with EDS'76 virus, serologically positive birds appeared to be protected for the greater part to BC14 virus challenge at 50 weeks of age, while negative birds seemed to be fully susceptible. Chicks hatched from eggs collected in the third and fourth week after infection of the dams had maternal antibodies. Fertility and hatchability of apparently normally shelled eggs seemed not to be affected after BC14 virus infection of the dams. Intensive contact with contaminated faeces is probably an indispensable condition for lateral transmission of the virus.  相似文献   

18.
The ability of Salmonella enterica serotype Enteritidis isolates to adhere to immobilized secretions of the isthmus of the laying hen was determined in an ELISA-type assay. One-third of the 56 isolates tested in the logarithmic growth phase, adhered to the isthmal secretions. Using a binding assay of the isolates to thin paraffin sections of the oviduct, we demonstrated that the receptor of the adhesion was localized inside the tubular gland cells of the isthmus. The adhesion to immobilized isthmal secretions as well as to the paraffin sections was blocked by the addition of mannose. A fimD mutant of S. Enteritidis, lacking type 1 fimbriae, did not adhere, confirming that the adhesion was mediated by type 1 fimbriae. Mannosylated glycoproteins were demonstrated in the isthmus glandular cells using confocal laser scanning microscopy by FITC-labelled Lens culinaris lectins. It is hypothesized that the binding of S. Enteritidis to isthmal secretions could play a role in the contamination of eggs through incorporation of the bacteria in the shell membranes.  相似文献   

19.
In Experiment 1, mature laying hens were inoculated intravaginally with 10(6) colony-forming units of Salmonella enterica serovar enteritidis (S. enteritidis), Salmonella typhimurium, Salmonella infantis, Salmonella hadar, Salmonella heidelberg, or Salmonella montevideo to compare their abilities to colonize the reproductive organs of chickens and to contaminate eggs. Salmonella enteritidis was more frequently recovered (from 11 of 40 eggs, 27.5%) than the other serovars, and especially the inner shell was contaminated with these organisms in 10 of 40 eggs (25.0%). The contamination rates and the viable counts in cloaca were significantly (P < 0.05) higher in hens inoculated with S. enteritidis than in those inoculated with the other serovars at 4 days postinoculation (PI). In the vagina, the positive rates were 90%-100% in hens inoculated with S. enteritidis, and the viable counts of the organisms in this portion were significantly (P < 0.05) higher than those of the other serovars at 2, 4, and 7 days PI. The ceca were colonized similarly by each serovar at 7 days PI. The spleen and ovary were infected with S. enteritidis in three and one hen, respectively. No Salmonella was recovered from liver and peripheral blood in any hen. Salmonella enteritidis was recovered from other oviductal portions than the vagina (10%-20%), whereas no forming egg was contaminated in the oviduct. In Experiment 2, the in vitro adherence of these six serovars to the vaginal epithelium was compared with vaginal explants. The mean number of S. enteritidis attaching to the secondary villi in the vaginal lumen was significantly (P < 0.05) higher than those of the other serovars. These results suggest that S. enteritidis has a specific advantage over the other Salmonella serovars by its capacity to colonize the vaginal tissues of hens, and this higher affinity of S. enteritidis to the vagina may play a significant role in the production of many S. enteritidis-contaminated eggs.  相似文献   

20.
R K Gast  C W Beard 《Avian diseases》1990,34(2):438-446
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   

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