Percloacal infection of chickens with Salmonella typhimurium

The characteristics of Salmonella typhimurium infection in hatchlings and adult poultry given by the intravenous, oral and percloacal routes were compared. Based on LD₅₀ determinations, 1-day-old birds were most susceptible to percloacal infection. It is claimed that this infection technique yields predictable results in terms of mortality and numbers of organisms in the liver, spleen and intestinal tissues. Though older birds do not die when given large doses of organisms by this route, small numbers are sufficient to establish transient infection or carriage in the intestine.Based on quantitative data, the course of the percloacal infection appeared similar to that given by the oral route in hatchlings; however, the number of organisms required to establish infection by the former route was significantly less. It is suggested that the percloacal infection route may be a useful model for studying Salmonella infection-immunity in birds, particularly if resistance mechanisms operating in the intestine are to be taken into account. The possibility that it may be an important infection route in natural circumstances must also be considered.     

Epizootiology of Salmonella typhimurium infection in chickens]

The incidence of S. typhimurium infections among fowl increased in thr region of Potsdam in general, and on various big farms in particular, 1976 and over the first half of 1977. The outbreaks included subclinical infections and clinically manifest diseases which caused remarkable loss of broilers from the affected stocks (up to 15.92 per cent). Parent stocks contaminated with S. typhimurium were to be the sources of infection in all cases. A total of 1,220 Salmonella strains were isolated from fowl and its environment, with 1,151 of them being S. typhimurium (2.98 per cent of all samples tested). The following amounts of S. typhimurium strains were isolated from different types of samples which had been collected from infected broiler stocks: 8.10 per cent from dead broilers, 5.86 per cent from dead broiler parents, 2.11 per cent from pulp linings of transport cages for day-old chicks, 1.23 per cent from litter, 1.0 per cent from hatching material (eggs or dead and jammed embryos, and 0.12 per cent from swabs used in hygiene supervision). No Salmonellae were isolated from feedstuff. The transmission of S. typhimurium, therefore, is though to have taken the route via the hatching egg and via congenitally infected chicks traded between breeders and propagation farms. The control and prophylaxis of S. typhimurium infections, therefore, should be based primarily on action in the centralised breeding stocks. Specific steps of such action are proposed. Fifty-three strains were biochemically and lysotypically analysed, with the following types being determined: ut/Ph 30 BT b, ut/Ph 30 BT c, n.c. 1/72/n.c. BT b, 2 n.c. BT a, and 1A/6 BT a. The first two types covered 84.9 per cent of all strains isolated from the fowl. All lysotype ut/Ph 30 strains isolated from fowl fell under the copenhagen variant which had rarely been isolated from man in the past. These results are likely to support the demand for a joint control programme for enteritis Salmonellae, with particular emphasis on S. typhimurium, for implementation in human and veterinary medicine.     

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.     

Antibody response to experimental Salmonella typhimurium infection in chickens measured by ELISA

An indirect ELISA has been developed to detect Salmonella typhimurium antibodies in chicken sera, using whole bacterial cell protein, flagellar protein or lipopolysaccharide as antigens. In experimental infections high concentrations of S typhimurium-specific IgG persisted after the faecal excretion of S typhimurium had ceased, whereas the specific IgM response was transitory. Some uninfected chickens placed in contact with experimentally infected birds developed high IgG titres in the absence of detectable faecal excretion. Other S typhimurium strains, which varied in their invasive abilities, also induced high titres of IgG. The ELISA allowed chickens infected experimentally with S typhimurium to be differentiated from chickens infected with 10 other serotypes, including S enteritidis. The use of whole blood in place of serum in the ELISA reduced the titres slightly. The storage of serum dried on to filter paper strips for four weeks produced little change in ELISA antibody titre, and the treatment of such strips with phenol or chloroform vapour had little or no effect on the antibody titre.     

Effect of reticuloendotheliosis virus on the response of chickens to Salmonella typhimurium infection

Groups of 25 chickens free of maternal antibody to reticuloendotheliosis virus (REV) were inoculated with either third or seventh passage REV at either one or seven days of age. Some of the birds inoculated at day 1 with REV were inoculated with Salmonella typhimurium either concurrently or six or 13 days later while some of those inoculated with REV at day 7 were inoculated concurrently with S typhimurium. At day old, infection with S typhimurium alone caused the death of 12 of 25 chicks whereas in the dual infection, using the third passage REV, 18 of 25 birds died. Similarly no seven or 14 day old chickens died when challenged with S typhimurium alone, but previous day-old infection with REV caused a respective mortality of eight of 25 and five of 25 birds. With the seventh passage REV a similar pattern was seen. At day old S typhimurium infection alone killed seven of 25 birds whereas combined with virus the mortality was 14 of 25 and while S typhimurium alone killed none of 25 chicks infected at seven days old, the mortality in birds also infected with REV was 14 of 25. Combined virus and bacterial infections did not increase the proportion of feathering defects in birds surviving S typhimurium infections. There was a significantly higher proportion of feathering defects in birds infected with third passage virus compared with seventh passage virus. Although a higher proportion of birds had antibody responses to REV in the seventh than in the third passage group, there was no discernible difference in the effect the different viruses had on chickens' susceptibility to S typhimurium.     

Experimental Salmonella typhimurium infection in calves.

The paper describes the clinical, bacteriological and pathological findings in experimental Salmonella typhimurium infection in calves. Oral doses of 10(8) and 10(9) organisms produced clinical disease and high mortality; doses ranging from 10(4)--10(7) organisms were less consistent in their action. Jersey calves appeared more susceptible to infection than Friesian calves. The clinical signs in most calves were pyrexia and a characteristic diarrhoea that lasted for up to 11 days; more severe symptoms were seen in the calves that received the higher doses. Following infection, all calves excreted S typhimurium in their faeces, the highest counts being observed in the calves that died. In the calves that survived, counts ranging from 10(2)--10(5)/g faeces occurred continuously for up to a maximum of 20 days and subsequent intermittent excretion occurred in a number of calves. In the calves that died, necrotic enteritis in the ileum and large intestine was the most striking lesion; lesions were uncommon in other organs. The findings are discussed in relation to the pathogenesis, diagnosis and control of the disease.     

Biological control of Salmonella typhimurium in young chickens

The effect of dietary lactose and anaerobic cultures of cecal microflora of mature chickens on the colonization of young broiler chickens by Salmonella typhimurium was evaluated. Newly hatched chicks were given either no treatment (controls), anaerobic cecal cultures, lactose (2.5%) in the drinking water, or both anaerobic cultures and lactose. Chicks were challenged per os at 3 days of age with either 10(6) or 10(8) S. typhimurium resistant to nalidixic acid and novobiocin. On day 10, the cecal contents of the chicks were examined for S. typhimurium, pH, short-chained volatile fatty acids (VFAs), undissociated VFAs, and lactic acid. Chicks given either lactose alone or cecal anaerobes alone had significantly (P less than 0.05) fewer S. typhimurium recovered from their ceca than the controls. Chicks given the combination of dietary lactose and cecal anaerobes had significantly fewer S. typhimurium recovered from their ceca than the chicks given dietary lactose or cecal anaerobes alone. Chicks given lactose had significant (P less than 0.05) increases in the lactic acid concentration of their cecal contents. Increased lactic acid concentrations were directly correlated to decreased cecal pH values and caused a reduction in the total concentration of VFAs but a significant (P less than 0.05) increase in the undissociated form of some VFAs.     

Oral administration of neomycin to chickens experimentally infected with Salmonella typhimurium.

Groups of healthy chickens with a light experimental Salmonella typhimurium infection were fed on a diet containing 225 g per ton (1016 kg) of neomycin for two days. This brought about only a slight reduction in the incidence of chickens that were excreting S typhimurium in their faeces. Examination of caecal contents two days after the cessation of treatment revealed the neomycin had not had any effect in eliminating infection. In one experiment, the neomycin administration resulted in the emergence of enormous populations of Escherichia coli in the alimentary tract of treated chickens that possessed multiple antibiotic resistance of the transmissible type. For these reasons the practice of feeding broiler chickens on diets containing neomycin immediately before slaughter should be actively discouraged.     

Effect of T-2 toxin on resistance to systemic Salmonella typhimurium infection of newly hatched chickens

Newly hatched chickens were treated with the trichothecene mycotoxin, T-2 toxin, during the first day of life. Control chickens were treated with other agents known to cause immunosuppression--cyclosporine, cyclophosphamide, and aflatoxin. Chickens were infected on day 6 (5 days after treatment with T-2 toxin) by intraperitoneal inoculation with Salmonella typhimurium. Blood samples were collected from treated chickens (noninfected) and used to assess the responsiveness of blood lymphocytes to T-cell or B-cell mitogens, phytohemagglutinin, or lipopolysaccharide, respectively. The T-2 toxin had a profound negative effect on the ability of the chickens to resist salmonellosis, as measured by survival. However, the toxin effect in reducing phytohemagglutinin- and lipopolysaccharide-stimulated mitogenesis, though significant (P greater than 0.05), was not severe. Our data indicate a direct effect of T-2 toxin on native resistance to systemic salmonellosis, which was not accompanied by marked alteration in T- or B-cell responses to mitogenic stimulation.     

Serological response of chickens naturally infected with Salmonella typhimurium detected by ELISA.

Four laying flocks of chickens in Britain, each with a history of Salmonella typhimurium infection, were investigated serologically and bacteriologically. Blood samples were taken from identified birds from a single house on each site and sent to the Central Veterinary Laboratory, Weybridge for serological examination using enzyme-linked immunosorbent assays (ELISA) and rapid slide agglutination test (RST) using stained S. pullorum. The identified birds were taken to the local Veterinary Investigation Centre for bacteriological examination. On site A no salmonellae were recovered from birds in the house chosen for serological examination. Of these birds approximately 20% had antibodies to S. typhimurium in ELISA which used either a lipopolysaccharide (LPS) or heat-extract (HE) antigen from S. typhimurium. S. typhimurium was recovered from birds in one other of the four houses on the same site; these birds were not tested serologically. On site B, S. typhimurium was isolated from 8% of the birds examined. Of the total tested serologically, a third to half were seropositive by S. typhimurium ELISA using the LPS and HE antigen respectively. A small proportion of birds was seropositive by S. enteritidis ELISA and RST. No salmonellae were isolated from the other two sites although about 10% of birds tested on site C were seropositive in S. typhimurium ELISA. Cross-reactions were seen between S. typhimurium antigens in the ELISA and experimentally prepared antiserum to S. enteritidis. The S. enteritidis ELISA was generally more specific although cross-reacting antibodies were detected in sera from birds on sites A and B.     

Effect of carbohydrates on Salmonella typhimurium colonization in broiler chickens

The effect of carbohydrates in the drinking water of broiler chickens on Salmonella typhimurium colonization was evaluated. Results indicate that mannose and lactose (2.5%) significantly (P less than 0.05) reduced intestinal colonization of S. typhimurium by at least one-half, as compared with dextrose, maltose, and sucrose. Lactose and mannose also significantly reduced (P less than 0.01) the mean log10 number of S. typhimurium in the cecal contents. Although mannose was the most effective sugar at blocking colonization, lactose may be more practical because it is effective and costs much less than mannose. Provision of carbohydrates in the drinking water had no significant effect on weight gain.     

Intracloacal Salmonella typhimurium infection of broiler chickens: reduction of colonization with anaerobic organisms and dietary lactose

The combined effect of treatments with dietary lactose plus anaerobic organisms on cecal colonization of broiler chicks by Salmonella typhimurium was evaluated. Chickens treated with a combination of anaerobic organisms and 7% dietary lactose were resistant to cecal colonization by S. typhimurium. The number of recoverable S. typhimurium cells per gram of cecal contents taken on days 10 and 15 after infection was significantly reduced. Treatment with anaerobes without the addition of lactose did not effectively control cecal colonization. Intracloacal inoculations with bacterial concentrations that varied by 10,000-fold resulted in roughly similar levels of colonization. The treatments resulted in reduced cecal pH and elevated levels of undissociated volatile fatty acids. Statistically significant correlations (P less than 0.01) were observed between the S. typhimurium concentrations in cecal material and the concentrations of undissociated fatty acids (r = -0.79, and between the bacterial counts and pH (r = 0.72).     

Infection and immune responses in chickens exposed to Salmonella typhimurium

The transmission of Salmonella typhimurium among adult chickens maintained in wire-floored cages was examined. Within 6 days, organisms had spread from infected seed chickens to the majority of uninoculated chickens. Initially, organisms were found in the intestinal tract alone, but by day 20, all chickens were infected, and most of these had organisms in the liver, spleen, and intestinal tract. Antibodies to whole bacterial cells and lipopolysaccharide were detected in the serum and bile of all chickens from day 24. Clearance of organisms from the tissues was not apparent until after day 33. Cell-mediated immunity to salmonella antigens was also induced in chickens that naturally acquired the infection. The role of these parameters of immunity in the clearance of organisms is discussed.     

Infection and reinfection of chickens with Salmonella typhimurium: bacteriology and immune responses.

Four-day-old chickens infected orally with a spectinomycin-resistant (Spcr) mutant of a highly invasive avian Salmonella typhimurium strain excreted salmonellae in the feces for at least 10 weeks. When these chickens were reinfected at this time with a nalidixic acid-resistant (Nalr) mutant of the same strain, they excreted this mutant in significantly smaller numbers (P less than 0.01) than did a previously uninfected control group. The Nalr mutant had a shorter survival rate in the tissues of the immunized chickens than in tissues of the control birds. The Spcr mutant stimulated strong IgG, IgA, and IgM responses in serum, small-intestinal contents, and bile. These were detected by enzyme-linked immunosorbent assay (ELISA) against antigens of crude whole bacterial cell protein sonicate, lipopolysaccharide, flagella, and outer-membrane proteins. There was some evidence of an anamnestic response with IgA in bile following reinfection with the Salmonella. The peak response of antibody-producing cells from the spleens of infected chickens, assayed by solid-phase ELISA, occurred at 3 weeks postinoculation. A strong delayed hypersensitivity reaction, detected by foot-pad swelling after inoculation with either whole-cell or outer-membrane proteins, was observed between 2 and 5 weeks after infection with the Spcr mutant. The data indicate that outer-membrane proteins are major immunogens for both humoral and cell-mediated arms of the immune system.