Reduction of fecal shedding and egg contamination of Salmonella enteritidis by increasing the number of heterophil adaptations

Serial passage of Salmonella enteritidis (SE) in chicken heterophils resulted in heterophil-adapted SE (HASE). We now report that an additional five heterophil passages have further reduced the number and frequency of fecal shedding of HASE. Eleven-times HASE (11 x HASE) given to 12 laying hens for three consecutive days reduced fecal shedding of 11 x HASE to three isolations from fecal samples during the 70-day postexposure observation period. Hens were exposed to challenge SE 74 days after treatment with 11 x HASE. Three of 12 11 x HASE-treated hens were positive for challenge SE (11/396 fecal samples, or 2.8%) between days 5 and 40 postchallenge, whereas all 12 challenge control birds were positive (118/420 fecal samples, or 28.1%) for SE. None of 12 11 x HASE-treated hens was fecal positive from day 9 postchallenge, whereas 10 of 12 challenge control hens (82/372 fecal samples, or 22.0%) remained positive until day 40, the termination of the experiment. None of 525 eggs and eggshells cultured after 11 x HASE exposure was positive for Salmonella, and none of 422 eggs and eggshells cultured after challenge SE exposure was positive for Salmonella. Eggs or eggshells from challenge control hens were positive for Salmonella in 12/479 (2.5%) cases after challenge SE exposure.     

Salmonella prevalence in crops of Ontario and Quebec broiler chickens at slaughter

Swabs of crop contents of 635 broiler chickens were obtained from 9 Ontario and 12 Quebec processing plants and cultured for Salmonella to determine prevalence in broiler crops. Serotypes of positive cultures were determined to evaluate the serotype profile. The overall prevalence of contamination was low (4.3%). Prevalence was higher in broilers sampled in Quebec (5.8%) than in those sampled in Ontario (2.2%). In Quebec, there were differences in prevalence among the groups of broilers sampled at the various plants. These differences were believed to be attributable to differences in Salmonella prevalence among groups of flocks delivered to the plants due to the limited exposure of the chickens to the plant. The serotype profile of Salmonella isolated from the crops of broilers in this study was similar in several respects to profiles obtained from other surveys of Canadian broiler flocks using either environmental samples or cloacal swabs. Similarities included: predominance of Salmonella hadar and Salmonella heidelberg; several other common serotypes at a low prevalence; little Salmonella enteritidis isolated in other studies, and no S. enteritidis isolated in this study. Results of this field survey of Salmonella in crops of broilers are similar to those of Canadian studies of other internal and environmental sites of broilers. The similarity indicates that monitoring of Salmonella environments of flocks of live broiler chickens should define profiles of Salmonella contamination of the carcasses and would also aid in determination of Salmonella contamination status of broiler flocks. Such information would assist efforts to reduce Salmonella contamination in broiler chickens.     

Isolation of Salmonella from ovaries and oviducts from whole carcasses of spent hens

Spent hens containing hard-shelled eggs were obtained to study the influence of sample collection and sample preparation methodology on the detection of Salmonella in ovaries. Four hundred eighteen birds from 19 flocks were collected, and the carcasses were opened aseptically within 8-12 hours of collection. A sample set containing hard-shelled egg, ovary, and oviduct section were collected from each carcass, and surface contaminants were removed from ovaries with polyoxyethylene ether. Three of 19 flocks (15.8%) and six of 407 ovary samples were positive for Salmonella; two oviduct samples were positive (0.5%). No eggs were Salmonella-positive. Single and multiple serotypes were detected in ovaries. Results indicated that Salmonella recovery rates can be significantly affected by speed in processing samples after collection, by cleanliness of the tissue-collection environment (laboratory vs. slaughter plant), and by removal of surface contaminants.     

Prevalence of Salmonella in broilers at retail outlets, processing plants and farms in Malaysia

A study was conducted to estimate the prevalence of Salmonella among broilers retailed at wet-markets and processing plants. Litter and feed samples obtained from both broiler and breeder farms were also examined for Salmonella. A total of 158 out of 445 (35.5%) and 52 out of 104 (50.0%) broiler carcasses obtained from wet-markets and processing plants were contaminated with Salmonella, respectively. Salmonella was isolated from 14 out of 98 (14.3%) samples of intestinal content. Litter samples from broiler and breeder farms were positive for Salmonella, 8/40 (20%) and 2/10 (20%), respectively. Salmonella isolates (230) belonging to 15 different serovars were isolated. Predominant serovars were S. enteritidis, S. muenchen, S. kentucky and S. blockley.     

Effect of vaccination of hens with an avirulent strain of Salmonella typhimurium on immunity of progeny challenged with wild-Type Salmonella strains

The avirulent Salmonella typhimurium chi3985 was used to vaccinate white leghorn chickens at 16 and 18 weeks of age, and the effect of maternal antibody on Salmonella colonization of progeny of vaccinated hens was assessed with S. typhimurium F98 or chi3985. Progeny of hens that had been vaccinated at 1 and 3 or 2 and 4 weeks of age with chi3985 were used to determine the effect of maternal immunity on vaccine efficacy. Vaccination of hens induced long-lasting Salmonella-specific antibodies which were transferred into eggs and were detected as immunoglobulin G (IgG) in the egg yolk. Maternal antibody was detected in the progeny of vaccinated birds as IgG and IgA in serum and intestinal fluid, respectively. The titer of maternally transmitted IgG or IgA was highest in the first week of life of the progeny and declined with age. Maternal antibodies prevented colonization of the chicks by S. typhimurium chi3985 and reduced colonization by S. typhimurium F98. Overall, chicks from vaccinated hens had significantly higher antibody responses than did the progeny of nonvaccinated hens after oral infection with Salmonella strains. Maternal antibody reduced the efficacy of vaccination of progeny with chi3985 at 1 and 3 weeks of age. But vaccination at 2 and 4 weeks of age induced excellent protection against challenge with S. typhimurium F98 or S. enteritidis 27A PT 8 in birds from vaccinated hens and in specific-pathogen-free chickens. Vaccination of chickens at 2 and 4 weeks of age has been shown to protect the birds against challenge with homologous and heterologous Salmonella serotypes. A combination of vaccination of adult animals and use of the progeny of vaccinated birds will enhance effective control of Salmonella infections in the poultry industry. This will complement the present control of Salmonella-associated food poisoning caused by Salmonella enteritidis in eggs because the avirulent S. typhimurium vaccine strain chi3985 induced excellent protection against S. enteritidis in chickens.     

Evaluation of the chicken crop as a source of Salmonella contamination for broiler carcasses

Much previously published research has focused on the role of cecal and intestinal Salmonella contamination of poultry carcasses within commercial processing plants. Presently, we have evaluated the persistence of experimentally inoculated Salmonella enteritidis in the crops and ceca of commercial broiler chickens during the last week of growth (Weeks 6 to 7) and the presence of crop and cecal Salmonella in 7-wk-old broilers in a commercial processing plant. When broilers were inoculated with 1 x 10(6) cfu S. enteritidis at 6 wk of age by oral gavage, the incidence of crop and cecal contamination was equivalent 2d after challenge (30%), with only 1 of 29 crops contaminated and 0 of 29 ceca contaminated at 7 d following challenge. When broilers were inoculated with 1 x 10(8) cfu S. enteritidis at 6 wk of age by oral gavage, 2 d after challenge the crops and ceca were observed to be 57 and 67% positive for S. enteritidis, respectively. Seven days after inoculation with 1 x 10(8) S. enteritidis, the crops and ceca were 37 and 57% positive, respectively, for the challenge organism. At a commercial broiler processing plant, 286 of 550 crops from three flocks were Salmonella-positive, whereas only 73 of 500 ceca from these flocks were contaminated. Furthermore, data from this plant indicated that the crops were far more likely to rupture than ceca (86-fold) during processing, increasing the possibility of carcass contamination with Salmonella derived from crop contents. The results of these studies suggest that the crop may serve as a source of carcass contamination with Salmonella within some processing plants.     

Sanitation of biowaste compost by using Salmonella enteritidis as a pathogen indicator and survival of Salmonella in seepage water

The following investigations show the frequency of the occurrence of Salmonella in biowastes. Salmonellae, belonging to the serotypes Salmonella enteritidis, infantis and agona were detected in 50% of the investigated biowaste samples. In order to control the reliability of compositing techniques on eliminating pathogens, Salmonella enteritidis was used as a pathogen indicator, which was brought into a container composting process and investigated on it's decline. Although the input indicator bacteria were eliminated in every case latest until the end of container composting, Salmonella was detected in 36% of the investigated fresh compost samples. Every time when Salmonella was detected in input material, the same serotypes were to be found in seepage water and survived there until the end of intensive rot. In laboratory experiments the maximum survival time of Salmonella enteritidis in seepage water at +5 degrees C was 42 days. Seepage water was found out to be a reservoir for survival of Salmonellae and has to be considered as a permanent source of contamination. In the question of the disposal of seepage water there are disagreements between the instructions of TA Siedlungsabfall and TA Luft.     

Mice as carriers of Salmonella enteritidis on persistently infected poultry units

Evidence of the possible role of wild mice in the epidemiology of Salmonella enteritidis infection on broiler breeder and layer breeder units was obtained by a bacteriological examination of local mice. Persistent S enteritidis infection in birds on these units had been a problem and a high proportion of the mice were found to carry salmonella. S enteritidis was isolated from the liver and the intestine of most of the mice, indicating a systemic infection. Three-week-old chicks were infected by contact with droppings from mice which had been infected experimentally with S enteritidis two and five months previously. Wild mice infected artificially or naturally excreted S enteritidis intermittently, with up to 10(4) organisms in some individual droppings. A naturally infected mouse which died after intermittently excreting small numbers of S enteritidis in its droppings for 19 weeks had 10(4) organisms/g of liver and 10(3)/g of macerated intestine and contents. S enteritidis was also found in fetal tissue in a naturally infected mouse suggesting the possibility that the organism might be transmitted vertically.     

Salmonella enteritidis colonization in turkey poults

An experimental trial on the colonization of two Salmonella enteritidis strains (phage types 4 and 8) originating from meat turkey flocks, were carried out. Three-day old poults were inoculated orally with approximately 10(6) cfu/bird (one group with PT8 and the other with PT4). clinical signs were not observed in any of the groups. The total reisolation rates from cloacal swabs in birds inoculated with PT4 was higher than from birds inoculated with PT8. The inoculated strains could also be detected in contact birds. Examination of internal organs 21 days p.i. revealed higher isolation rates in the group infected with PT4 than with PT8. The results indicate that both phage types of S. enteritidis were able to colonize the intestinal tract and the internal organs of turkey poults. However, the colonization and duration of shedding differed between the two phage types. This may be due to the fact that PT8 strain used was free from the S. e. virulence plasmid 37 MDa.     

Frequency of isolation of Salmonella from protective foot covers worn in broiler houses as compared to drag-swab sampling

In this study we tested the hypothesis that the frequency of Salmonella isolation from protective foot covers worn in individual broiler production houses would compare favorably to isolation rates obtained from conventional drag-swab methods. Salmonella was detected with equal frequency from protective foot covers and drag-swab assemblies on nine individual broiler farms over three separate sampling periods. Salmonella was detected in 13 of a total 27 individual samplings by culturing the protective foot covers, whereas positive detections occurred in 16 of a total 27 samplings when using the drag-swab method. Of the total number of houses identified as positive, these frequencies were unaltered when evaluated against the flock status of each farm at the time of sampling. Both methods were equally as likely to detect Salmonella when houses were either vacant (awaiting the placement of the next flock) or occupied (currently housing chickens of any age). In addition to highlighting the development of a potential new Salmonella monitoring technique, this study reinforces our current understanding regarding the importance of stringent biosecurity practices on poultry farms.     

Evaluation of bacterins containing three predominant phage types of Salmonella enteritidis for prevention of infection in egg-laying chickens

Six Salmonella enteritidis bacterin formulations differing in adjuvant content and whole-cell inactivation procedures were evaluated in egg-laying chickens. Chickens given S enteritidis bacterins containing modified Freund's incomplete adjuvant had greater humoral immune responses to S enteritidis than did birds given other bacterin formulations (P < 0.05). Better protection against infection by S enteritidis phage types 8, 13a, and 23 was obtained in birds vaccinated with bacterin 5. Bacterin 5 contained S enteritidis cells inactivated by 20% acetone and modified Freund's incomplete adjuvant.     

Group selection for adaptation to multiple-hen cages: humoral immune response

A selected line of White Leghorns, which has shown improved survivability and reduced feather loss in large multiple-hen cages, was evaluated for humoral immune response to SRBC under both stressed and unstressed conditions. Three lines of chickens (selected, control, and commercial) were housed in either single- (1 hen) or multiple-hen cages (12 hens, social competition) and subjected to a cold ambient temperature (0 C) at 33 wk of age and to two heating episodes (38 C) at 44 wk of age. Each hen was challenged intravenously with 1 mL of a 7% saline suspension of SRBC at the time that cold exposure was initiated. Hens subjected to high ambient temperatures had been exposed previously to a cold temperature, but were not challenged with SRBC until 16 to 18 h following the end of the second heating episode. Exposure to cold caused immunosuppression in single-caged hens, but not in hens in colony cages. Single- vs colony-caged hens of the control environment challenged with SRBC at 33 wk of age had similar primary hemagglutinin responses to SRBC. Hens subjected to heat experienced immunosuppression at 9 and 12 d following challenge to SRBC when compared to the controls. Hens of multiple-bird cages challenged with antigen at 44 wk of age had a significantly lower hemagglutinin response to SRBC than those reared in single-bird cages. The three lines of genetic stock had similar primary hemagglutinin responses to SRBC; the interactions of genetic stock with cage size or environmental temperature were not significant. It was concluded that genetically selecting hens for survival in multiple-hen cages did not affect their humoral immune response to SRBC.     

Serological study of the occurrence of L. hardjo in sheep in The Netherlands

Sheep (3918) from 137 farms in the regions of North-, West- and Mid-Netherlands and Gelderland were serologically investigated for the presence of antibodies against Leptospira hardjo. Antibodies were detected in 3.3% of the sheep. There were large regional differences with respect to both the percentage of positive sheep and the percentage of positive flocks. All sera from sheep in Gelderland were negative. In West- en Mid-Netherlands there were 0.9 and 6.5% positive sera, respectively, and 19.4 and 32.7% positive flocks. The percentage of positive sheep per positive flocks varied from 1 tot 51.6. Serological positive sheep were from farms with and without cattle. On farms with cattle, there was no clear relationship between serologically sheep and the presence of hardjo antibodies in cattle. It thus seems plausible that sheep can be infected with hardjo independently of cattle.     

Changes in microflora of the cloaca and oviduct of hens after intracloacal or intravaginal inoculation with Salmonella enteritidis

Quantitative and qualitative microbiological examination was carried out on cloacal and oviductal contents pre- and postinfection with Salmonella enteritidis (SE) intracloacally or intravaginally. Before inoculation with SE, the means +/- standard deviation (SD) of total bacterial counts, anaerobic bacterial counts, and aerobic bacterial counts in the cloaca were log10 7.7 +/- 0.7, 7.4 +/- 0.2, and 6.9 +/- 0.8 colony-forming units (CFU)/g, respectively. The predominant bacteria were Bacteroidaceae, Lactobacillus, and Escherichia coli. Before inoculation with SE, the means +/- SD of total bacterial counts, anaerobic bacterial counts, and aerobic bacterial counts in the vagina were log10 5.7 +/- 1.4, 5.5 +/- 1.3, and 3.6 +/- 2.7 CFU/g, respectively. Bacteroidaceae and Lactobacillus were predominant. Following inoculation with SE, only the cloacal population of Lactobacillus in hens inoculated intracloacally was significantly increased compared to that before the inoculation. Other indigenous microflora were stable even after the inoculation. In the uterus, very few bacteria, Lactobacillus and Staphylococcus, were isolated. Five of 20 eggs (25%) from hens inoculated with SE intravaginally were positive for SE, whereas no SE was recovered from 22 eggs in hens inoculated with SE intracloacally. SE was recovered from the uterus after intravaginal inoculation with SE and from the vagina after intracloacal inoculation with SE. Contamination may ascend from the cloaca into the lower parts of the oviduct and subsequently contaminated eggs may occur.     

Clinical and health care cost consequences of infective endocarditis in mitral valve prolapse

In 1990-1991, a national survey was conducted to estimate the prevalence of Salmonella species among Canadian commercial turkey flocks. Two hundred and seventy flocks were randomly selected across Canada. The proportion sampled from each province was selected according to each province's share of the national turkey market. Samples, consisting of 12 pooled litter and four pooled dust samples, were used to determine the Salmonella status of the environment of each flock. Additionally, a one kilogram sample of feed was taken from each flock premise. Salmonella was recovered from environmental samples in 234/270 (86.7%) of flocks and from feed samples in 26/266 (9.8%) of flocks. Forty-eight different Salmonella serovars were isolated from flock environmental samples. The most prevalent serovars were S. anatum, S. hadar, S. agona, S. heidelberg and S. saintpaul which were isolated from 53/270 (19.6%), 49/270 (18.1%), 49/270 (18.1%), 42/270 (15.6%) and 34/270 (12.6%) flocks, respectively.     

Bacteriological and serological investigation of persistent Salmonella enteritidis infection in an integrated poultry organisation

Bacteriological monitoring of broiler breeder farms, the hatchery, rendering plant and animal feed mill during 1991 identified a number of potential cross-contamination hazards, such as the use of processed poultry proteins in the company feed mill and contamination of egg trolleys and trays, which may have led to widespread dissemination of Salmonella enteritidis within an integrated poultry organisation. Serological monitoring of the flocks suggested that, in most cases, substantial exposure to S. enteritidis infection occurred during the mid-rearing stage whereas routine bacteriological monitoring of poultry house litter and dust samples, and meconium samples taken in the hatchery identified infection only after the onset of the laying period. At least 10 phage types and six plasmid profile types of S. enteritidis were identified in historic submissions from the organisation including one apparently specific plasmid profile type that was distributed throughout the various parts of the company. During sampling for this investigation, most of these strains were not identified, and the number of plasmid profile types was reduced to a single common UK type.     

Simulation of the transmission of Salmonella enteritidis phage type 4 in a flock of laying hens

Simulation of disease transmission in laying flocks infected with Salmonella enteritidis phage type 4 over a 48-week egg-production period indicated that the maximum weekly incidence risk could range from 0.05 to 0.28, and the maximum proportion of culture-positive birds could range from 0.20 to 0.77 of the flock, depending on the effective contact rate. If the egg contamination proportion were 0.08, contaminated egg production could vary from a weekly maximum of 0.42 per cent to 2.24 per cent depending on the effective contact rate, but the actual rate of contamination was more important in determining the numbers of infected eggs produced. The results from previous studies suggest that this proportion could range from 0.075 to 0.25. The model produced levels of infected and immune birds similar to those reported in the literature, suggesting effective contact rates of between 2 and 4.5. There is insufficient information on transmission cycles to validate the model, but it does provide a mechanism for consolidating research findings, reviewing areas for further research, and aiding more effective planning for disease control.     

Momentum versus extinction effects in the treatment of self-injurious escape behavior

S. Enteritidis HY-1 isolated during quarantine from chicks imported from England was used. Laying hens at the age of 34 weeks were inoculated orally with 10(10) organisms (10 birds), intramuscularly with 10(9) (5 birds), and intravenously with 10(9) (5 birds). Egg production did not change in hens infected orally, although it was reduced in hens infected intramuscularly for 2-3 weeks post inoculation. For one month, internally infected eggs of which the shells were not contaminated were found: one out of 65 eggs in hens infected orally and three out of 36 eggs in hens infected intramuscularly. This experiment demonstrated the ability of S. Enteritidis isolated from chicks imported from England to cause transovarian infection.     

CD56bright natural killer cell subsets: characterization of distinct functional responses to interleukin-2 and the c-kit ligand

Horizontal transmission of Salmonella enteritidis and the effect of airflow on spreading were examined in 80 5-wk-old chickens divided into five groups. Sixteen chickens in each group were placed in four cages in a row separated by wire. One among four chickens placed in a cage at the downwind end of the row was inoculated orally with 10(9) colony-forming units of S. enteritidis. Cecal droppings, drinking water, and feed were cultured every day. Horizontal transmission was rapid in the row with low air velocity but slow in the row with high air velocity. However, in another experiment, where the inoculated chicken was situated in a cage upstream in the airflow, horizontal transmission was equally rapid whether the airflow was rapid or slow. Contamination of feed and water never preceded the appearance of positive cecal droppings. These findings suggest that the rapidity of horizontal transmission of S. enteritidis may be affected by airflow patterns.     

Drug-induced orthostatic hypotension in the elderly: avoiding its onset

Fresh and dried faeces of laying hens from battery fattening and faeces from complete confinement rearing were investigated with bacteriological and physico-chemical methods. The comparison shows that ventilated faeces from conveyor belts with significantly higher values of the autochthonous faecal flora (endogerms, coliform germs, faecal streptococci) are most unfavourable from an epidemiological-bacteriological point of view. Salmonellae occurred very frequently both in fresh faeces (in 76.9% of the samples) and in ventilated faeces from conveyor belts (in 83.9% of the samples), whereas this agent was only detectable in 1.9% of the samples of faeces from complete refinement rearing. Fifteen serovar were isolated, most frequently S. enteritidis (29.4%), but S. typhimurium only once (1.96%). The highest amount of salmonellae germs was found with 105 g in faeces from conveyor belts. There are no objections to the direct utilization of faeces as fertilizers from an epidemiological point of view. For epidemiological reasons, ventilated faeces from conveyor belts should not be directly sprayed over the soil. After air-drying in henhouses, these faeces should be stored and composted before they are used in agriculture. It was not possible to cultivate salmonellae and E. coli in summer and winter after the composting of dried hens' faeces. The salmonellae were no longer detectable from the 4th day onwards, native salmonellae from the 7th day (summer) and the 25th day (winter) onwards, and E. coli from the 88th day onwards. If all parameters, particularly the grain size, are observed, an epidemiologically perfect product comes into being after the fast drying of faeces.