Current perspectives in avian salmonellosis: Vaccines and immune mechanisms of protection

Salmonellosis is one of the most prevalent foodborne diseases worldwide. Food animals have been identified as reservoirs for nontyphoid Salmonella infections. in poultry, host-specific Salmonella infections cause fowl typhoid and pullorum diseases that produce economic losses in different parts of the world. Several measures have been used to prevent and control Salmonella infections in poultry, and vaccination is the most practical measure because it avoids contamination of poultry products and by-products and prevents disease in humans. Salmonella vaccines can decrease public health risk by reducing colonization and organ invasion, including invasion of reproductive tissues, and by diminishing fecal shedding and environmental contamination. We review available information on the host-specific and non-host-specific Salmonella serotypes found in poultry and the improved understanding of the pathogenesis of and immune responses to infection. We also include some approaches based on updated publications regarding killed and live attenuated vaccines and their immune mechanisms of protection.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP), BrazilFAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo, Sao Paulo, Brazil) [07/53046-7

Salmonella antibiotic-mutant strains reduce fecal shedding and organ invasion in broiler chicks

We investigated the exposure to antibiotics in the production of antibiotic-mutant strains of Salmonella. Ten isolates of poultry origin were assayed for antibiotic susceptibilities. One strain of Salmonella Enteritidis, one of Salmonella Heidelberg, and one of Salmonella Typhimurium were selected to induce antimicrobial resistance. Each strain was exposed to high concentrations of streptomycin, rifampicin, and nalidixic acid, respectively. Parent and antibiotic-mutant strains were assayed for antibiotic susceptibilities using a commercial microdilution test and the disk susceptibility test. The strains were assessed for virulence genes and evaluated for fecal shedding, cecal colonization, organ invasion, and mean Salmonella counts after inoculation in 1-day-old chicks. The study revealed that exposure to high concentrations of streptomycin produced the antibiotic-mutant strain SE/LABOR/USP/08 and the exposure to rifampicin produced the antibiotic-mutant SH/LABOR/USP/08. These strains showed significantly reduced fecal shedding (P = 0.05) and organ invasion, persisting less than the parental strains and showing no clinical signs in inoculated chicks. High concentrations of nalidixic acid produced the antibiotic-mutant strain ST/LABOR/USP/08, which did not show any differences compared with the parent strain. Likewise, SE/LABOR/USP/08 did not show the expression of plasmid-encoded fimbriae (pefA) and plasmid virulence protein (spvC), suggesting that after exposure to streptomycin, the parent isolate lost the original gene expression, reducing fecal shedding and organ invasion in inoculated chicks.Biovet S.A., Tarragona, SpainFAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (Sao Paulo, Brazil)[07/53046-7

Prevention of Salmonella Typhimurium colonization and organ invasion by combination treatment in broiler chicks

The effects in broiler chicks of treatment with a competitive exclusion (CE) product, an experimental dietary probiotic, and the abiotic beta-glucan on cecal colonization, organ invasion, and serum and intestinal IgG and IgA levels to Salmonella challenge was evaluated. Four groups of 1-d-old chicks were treated by oral gavage on d 1 with an appropriate dose of a commercial CE product. Three groups received daily doses of probiotic, beta-glucan, or both, for 6 d. Three other groups were fed daily from d 1 onwards with probiotic, beta-glucan, or both. Subgroups of 30 chicks from each group were challenged on d 1, 9, 16, or 23 with 10(7) cfu/mL of Salmonella Typhimurium (1769NR) and killed 7 d later. Control groups were maintained untreated and remained unchallenged (negative control), or were challenged with Salmonella Typhimurium (1769NR; positive control), as described above. Cecum, liver, and spleen samples were examined for the presence of Salmonella, whereas serum and intestinal fluid samples were assayed for total antibody (IgG and IgA) concentrations. Data were analyzed by 1-way ANOVA, and means were compared using Duncan`s multiple range test. In comparison with other treatments, those involving CE product and beta-glucan, with or without probiotic during the first week, resulted in a superior inhibition of cecal colonization and organ invasion by Salmonella and also offered a higher level of protection (P < 0.05). During the second week, treatments containing experimental dietary probiotic and beta-glucan, with or without CE product, resulted in an inhibition of liver invasion (P < 0.05). The IgA levels were significantly higher (P < 0.05) in intestinal fluid compared with serum, whereas IgG had low levels. The results in the first and third week indicate that combination treatments involving CE product, probiotic, and beta-glucan are a more effective control of Salmonella colonization than the corresponding individual preparations.CNPq Conselho Nacional de Desenvolvimento Cientifico e TecnologicoFAPESP Fundacao de Amparo a Pesquisa do Estado de Sao Paulo[02/10386-9

In vitro virucidal and bactericidal activities of Aviclor (a formulation of sodium dichloroisocyanurate) against pathogens of poultry origin

This study was conducted to determine whether the new disinfectant Aviclor (HidroAll do Brazil Ltda., Valinhos, São Paulo, Brazil), a formulation containing sodium dichloroisocyanurate, acetylsalicylic acid, sodium chloride, and a dye pigment, was effective in killing a group of selected pathogens obtained from chickens. The use of Aviclor completely eliminated several viruses, including infectious laryngotracheitis virus, infectious bronchitis virus, infectious bursal disease virus, and rotavirus, at disinfectant concentrations in the range of 0.5 to 0.77 g/L, with exposure times between 5 and 10 min. In addition, Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica serovar Enteritidis phage type 4, Clostridium perfringens, and Staphylococcus aureus were killed after treatments with Aviclor concentrations ranging from 0.67 g/L for 15 min to 0.93 g/L for 20 min. Pseudomonas aeruginosa was the most sensitive to the product, and S. aureus was the most resistant to the disinfectant; the concentration required for eliminating the bacteria was 1.067 g/L for 15 min. We conclude that because of the virucidal and bactericidal activities of Aviclor and the short effective exposure times, together with the low corrosive action and the absence of toxicity to birds and the environment, Aviclor is suitable as a disinfectant for poultry productio