RESUMO

Salmonella enterica subsp. enterica serovar Gallinarum biovar Gallinarum (SG) causes fowl typhoid (FT), a septicaemic disease which can result in high mortality in poultry flocks. The absence of flagella in SG is thought to favour systemic invasion, since bacterial recognition via Toll-like receptor (TLR)-5 does not take place during the early stages of FT. In the present study, chicks susceptible to FT were inoculated with a wild type SG (SG) or its flagellated motile derivative (SG Fla(+)). In experiment 1, mortality and clinical signs were assessed, whereas in experiment 2, gross pathology, histopathology, systemic invasion and immune responses were evaluated. SG Fla(+) infection resulted in later development of clinical signs, lower mortality, lower bacterial numbers in the liver and spleen, and less severe pathological changes compared to SG. The CD8(+) T lymphocyte population was higher in the livers of chicks infected with SG at 4 days post-inoculation (dpi). Chicks infected with SG had increased expression of interleukin (IL)-6 mRNA in the caecal tonsil at 1 dpi and increased expression of IL-18 mRNA in the spleen at 4 dpi. In contrast, the CD4(+) T lymphocyte population was higher at 6 dpi in the livers of birds infected with SG Fla(+). Therefore, flagella appeared to modulate the chicken immune response towards a CD4(+) T profile, resulting in more efficient bacterial clearance from systemic sites and milder infection.

Assuntos

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The rise of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in food-producing animals is a growing concern for public health. We investigated ESBL producers isolated from broiler chickens in Brazil and characterized 19 CTX-M-2-producing E. coli. The ISCR1 was detected upstream of the chromosome-located gene bla(CTX-M-2), associated with sul-1 type integron structure. CTX-M-2-producing E. coli exhibited different PFGE-types and phylogenetic groups, showing a non-clonal dissemination. The sequence types found (ST93, ST155 and ST2309) have been associated with humans and animals worldwide. Herein, we report the chromosomal location of bla(CTX-M-2) on E. coli, highlighting the risks of multidrug-resistant bacteria in food-producing animals.

Assuntos

RESUMO

Salmonella enterica serovar Gallinarum (SG) is an intracellular pathogen of chickens. To survive, to invade and to multiply in the intestinal tract and intracellularly it depends on its ability to produce energy in anaerobic conditions. The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHIJ) operons in Salmonella Typhimurium (STM) encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO, TMAO, and nitrate, respectively. They are regulated in response to nitrate and oxygen availability and changes in cell growth rate. In this study mortality rates of chickens challenged with mutants of Salmonella Gallinarum, which were defective in utilising anaerobic electron acceptors, were assessed in comparison to group of bird challenged with wild strain. The greatest degree of attenuation was observed with mutations affecting nitrate reductase (napA, narG) with additional attenuations induced by a mutation affecting fumarate reductase (frdA) and a double mutant (dmsA torC) affecting DMSO and TMAO reductase.

RESUMO

Young poultry are very susceptible to Salmonella Enteritidis (SE) infections because of the absence of complete intestinal flora colonization and an immature immune system. This study evaluated the role of passive immunity on the resistance of young birds against early infections caused by SE. The progeny of broiler breeders vaccinated with an oil-emulsion bacterin was compared to the progeny of unvaccinated birds. Efficacy was determined by challenging birds at 1 and 14 days of age with SE Nal Spc strain, phage type 4. After challenge at 1 day of age, the progeny of vaccinated birds presented a significantly lower number (log10) of SE Nal Spc reisolation (P < 0.05) in liver (2.21), spleen (2.31), and cecal contents (2.85) compared with control groups (2.76, 3.02, and 6.03, respectively). The examination of the internal organs, 3 days after infection, revealed that 28% of the birds (7/25) from vaccinated breeders were positive, whereas 100% (25/25) of the chicks derived from unvaccinated birds were positive. Birds challenged at 14 days of age presented a lower number of positive samples compared with those challenged at 1 day of age, and the progeny of vaccinated birds presented statistically lower numbers (log10) of colony-forming units/ml of SE Nal Spc only in the cecal contents compared with nonvaccinated breeder progeny (2.11 vs. 2.94). Age seems to influence the susceptibility of birds to SE infections: in control groups, the number of positive birds at 14 days of age (9/25) was lower when compared with the group infected at 1 day of age (25/25). The number of positive fecal samples of the progeny of vaccinated birds was significantly lower (36) than those of the control group (108) after challenge at 1 day of age. Unchallenged progeny of vaccinated birds presented passive antibodies detectable by enzyme-linked immunosorbent assay (ELISA) up to 21 days of age. On the other hand, antibodies of the control group were detected by ELISA 14 days after challenge. These results show a significant contribution of breeder vaccination by increasing the resistance of the progeny against early SE infections. However, the bacteria were not completely eliminated, suggesting that additional procedures are needed to effectively control SE infections.

Assuntos

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This study aimed at evaluating the susceptibility of commercial laying hens to Salmonella Gallinarum (SG). Two experiments were carried using a mutant strain of Salmonella Gallinarum resistant to nalidix acid (SGNALr). In the first trial, the resistance of birds was evaluated based on clinical signs, faecal shedding, and mortality. It was carried out with six lines of commercial layers being three light white layers, considered to be resistant to SG (W1, W2, W3), and three semi-heavy brown varieties (B1, B2, B3), considered susceptible to SG. Each group contained 15 one-day-old birds. Hens were inoculated in the crop at 5 days of age with 0.2 mL of SGNALr neat culture. In addition, to each brown variety, a new group of 15 birds was challenged with 0.2mL of the same SGNALr culture diluted at 10-3. At the end of the first experiment, the surviving birds were sacrificed, and microbiological culture of liver and spleen was performed. In the second experiment, white and brown birds were inoculated with neat culture at five days of age. Samples were collected for evaluation of blood parameters and histopathology assessment at 1, 3, 5, 7, 9, 12, and 14 days post-infection. The results of the first experiment showed higher resistance of white birds (p 0.05), although there was no uniformity in the responses against fowl typhoid among the birds within these groups. In the second experiment, there were differences between white and brown birds both in blood parameters and in organ lesion intensity.

RESUMO

This study aimed at evaluating the susceptibility of commercial laying hens to Salmonella Gallinarum (SG). Two experiments were carried using a mutant strain of Salmonella Gallinarum resistant to nalidix acid (SGNALr). In the first trial, the resistance of birds was evaluated based on clinical signs, faecal shedding, and mortality. It was carried out with six lines of commercial layers being three light white layers, considered to be resistant to SG (W1, W2, W3), and three semi-heavy brown varieties (B1, B2, B3), considered susceptible to SG. Each group contained 15 one-day-old birds. Hens were inoculated in the crop at 5 days of age with 0.2 mL of SGNALr neat culture. In addition, to each brown variety, a new group of 15 birds was challenged with 0.2mL of the same SGNALr culture diluted at 10-3. At the end of the first experiment, the surviving birds were sacrificed, and microbiological culture of liver and spleen was performed. In the second experiment, white and brown birds were inoculated with neat culture at five days of age. Samples were collected for evaluation of blood parameters and histopathology assessment at 1, 3, 5, 7, 9, 12, and 14 days post-infection. The results of the first experiment showed higher resistance of white birds (p 0.05), although there was no uniformity in the responses against fowl typhoid among the birds within these groups. In the second experiment, there were differences between white and brown birds both in blood parameters and in organ lesion intensity.

RESUMO

BACKGROUND: Salmonellosis is a common problem worldwide in commercially reared poultry. It is associated with human Salmonellosis. No fully satisfactory method of control is available. METHOD: Nosodes to an antibiotic-resistant strain of Salmonella enterica serovar Enteritidis in D30 (30X) potency were prepared. One day old chicks (N = 180) were divided into four groups: two control and two different preparations of the nosode. Treatments were administered in drinking water for 10 days. The birds were challenged by a broth culture of the same Salmonella, by mouth, on day 17. Cloacal swabs were taken twice weekly for Salmonella enterica serovar Enteritidis. RESULTS: Birds receiving active treatment were less likely to grow the strain of Salmonella from cloacal swabs compared to control. CONCLUSION: Isopathy is low cost and non-toxic. It may have a role to play in the widespread problem of Salmonella in poultry. Further research should be conducted.

Assuntos

RESUMO

An experiment was carried out to investigate the biology of Salmonella Pullorum in two varieties of laying hens, from 5 days of age up to 9 months. One variety was resistant to systemic salmonellosis (light layers producing white eggs) and the other was considered susceptible (brown layers producing brown eggs). The brown birds were more affected by the infection, showing signs of clinical disease in the first month of life. Later, these signs disappeared, but postmortem examination revealed persistent gross pathological changes in the liver, spleen, heart and ovary. The rapid agglutination test detected reactors throughout the experiment, with the strongest agglutination from 1 to 7 months post-infection. S . Pullorum was isolated from some of the organs and the eggs laid throughout the experiment. The relationship between white birds and S . Pullorum was less intense, and there were no noticeable signs of disease. There were few gross pathological changes, and the bacteria were isolated infrequently and only for a brief period after infection, although contaminated eggs were laid by these birds. The strongest serological response in the white chickens occurred between the second and the fifth month post-infection.

RESUMO

An indirect ELISA using soluble whole cell antigen was used to screen serum samples obtained from breeder and layer flocks some of which had shown clinical or bacteriological evidence of infection with Salmonella Gallinarum or S. Pullorum. There was good correlation between Salmonella infection and the presence of serum samples showing high optical density (OD) values. Sera from seven flocks showing high values were retested using group D (0-1, 9, 12) lipopolysaccharide (LPS) and g,m-H flagella as detecting antigens. Sera from six flocks produced high OD values with LPS and low values with flagella confirming infection with a non-flagellate, group D Salmonella while one produced high values with both antigens indicating mixed infection with another group D serotype.

RESUMO

This experiment was undertaken to determine the possible presence of Salmonella in poultry diets.A total of two hundred samples of ration fr4om 4 commercial poultry feed industries were examined.The results revealed the presence of salmonellae in 10 cents of the samples studied and 14 serotypes were identified.The produce for Salmonella isolation included the pre-enrichment step and the strains were submited to antimicrobial tests.The 29 strains were resistant to the followings antimicrobial agents(porcents

Assuntos