A type III protein secretion system encoded by Salmonella pathogenicity island 2 (SPI2) has been found to be required for virulence and survival within macrophages. Here, SPI2 was shown to allow Salmonella typhimurium to avoid NADPH oxidase-dependent killing by macrophages. The ability of SPI2-mutant bacteria to survive in macrophages and to cause lethal infection in mice was restored by abrogation of the NADPH oxidase-dependent respiratory burst. Ultrastructural and immunofluorescence microscopy demonstrated efficient localization of the NADPH oxidase in the proximity of vacuoles containing SPI2-mutant but not wild-type bacteria, suggesting that SPI2 interferes with trafficking of oxidase-containing vesicles to the phagosome.

Salmonella Pathogenicity Island 2—Dependent Evasion of the

Great progress has been made in addressing global undernutrition over the past several decades, in part because of large increases in food production from agricultural expansion and intensification. Food systems, however, face continued increases in demand and growing environmental pressures. Most prominently, human-caused climate change will influence the quality and quantity of food we produce and our ability to distribute it equitably. Our capacity to ensure food security and nutritional adequacy in the face of rapidly changing biophysical conditions will be a major determinant of the next century's global burden of disease. In this article, we review the main pathways by which climate change may affect our food production systems-agriculture, fisheries, and livestock-as well as the socioeconomic forces that may influence equitable distribution.

https://www.annualreviews.org/doi/pdf/10.1146/annurev-publhealth-031816-044356

Climate Change and Global Food Systems: Potential Impacts on Food Security and Undernutrition.

Salmonellosis is the second leading cause of bacterial foodborne illness in the United States, and the great majority of these infections are associated with the consumption of products such as meat, poultry, eggs, milk, seafood, and fresh produce contaminated with Salmonella. The per capita consumption of meat and poultry in United States has increased significantly over the past century. This increase is especially evident with poultry products, where there has been a nearly 6-fold increase in chicken consumption and 17-fold increase in turkey consumption since 1909. The per capita consumption of pork has also increased over this time from 18.7 to 21.7 kg/yr. With this increase in meat and poultry consumption, the dynamics of animal production and consumer exposure have changed leading to new challenges in limiting salmonellosis. To meet the demands of consumers, more intensive agricultural practices have been adopted, which has likely changed the population characteristics of Salmonella present among poultry flocks and swine populations. In Salmonella isolated from swine in the United States, S. Typhimurium has replaced S. Choleraesuis as the predominant serovar in recent years. Among isolates from turkeys collected in 2004, serovars S. Senftenberg and S. Hadar were most common overall; however, S. Heidelberg was most common from clinical diagnostic sources, potentially indicating increased virulence. Salmonella Heidelberg was also the most commonly detected serovar among chicken isolates from clinically ill birds and Salmonella surveillance samples. Overall among the 10 serovars most commonly associated with human infections, 6 are also found in the top serovars of swine and poultry. These include S. Typhimurium, S. Enteritidis, S. Heidelberg, S. Montevideo, S. Saintpaul, and S. I 4,[5],12:i:-.

Salmonella challenges: prevalence in swine and poultry and potential pathogenicity of such isolates.

http://ssu.ac.ir/cms/fileadmin/user_upload/Moavenatha/MBehdashti/Pishgiri_Bimariha/00malt3/52.pdf

Non-typhoidal Salmonella infections in pigs: A closer look at epidemiology, pathogenesis and control

Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to (1) summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress, (2) illustrate that this pathophysiology is dependent on the intensity and duration of heat stress, (3) present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals. Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant reserves. Some phytochemicals, such as various types of flavonoids and related compounds, were shown to be beneficial in chronic heat-stressed poultry, but were less or not effective in non-heat-stressed counterparts. This supports the contention that antioxidant phytochemicals have potential under challenging conditions. Though substantial progress has been made in our understanding of the association between heat stress and oxidative stress, the means by which phytochemicals can alleviate oxidative stress have been sparsely explored.

https://biblio.ugent.be/publication/8518014/file/8519404.pdf

Association between heat stress and oxidative stress in poultry; mitochondrial dysfunction and dietary interventions with phytochemicals.

Understanding and controlling environmental conditions is crucial to successful poultry production and welfare. Heat stress is one of the most important environmental stressors challenging poultry production worldwide. The detrimental effects of heat stress on broilers and laying hens range from reduced growth and egg production to decreased poultry and egg quality and safety. Moreover, the negative impact of heat stress on poultry welfare has recently attracted increasing public awareness and concern. Much information has been published on the effects of heat stress on productivity and immune response in poultry. However, our knowledge of basic mechanisms associated to the reported effects, as well as related to poultry behavior and welfare under heat stress conditions is in fact scarce. Intervention strategies to deal with heat stress conditions have been the focus of many published studies. Nevertheless, effectiveness of most of the interventions has been variable or inconsistent. This review focuses on the scientific evidence available on the importance and impact of heat stress in poultry production, with emphasis on broilers and laying hens.

https://www.mdpi.com/2076-2615/3/2/356/pdf

Impact of Heat Stress on Poultry Production

The objective of this study was to determine whether abattoir pens can provide a Salmonella enterica infection source during the 2 to 4 h of preharvest holding. Previous work has suggested that pigs may be getting infected, but little has been reported on the environmental contamination of abattoir holding pens. For 24 groups of pigs studied ( approximately 150 animals/group) at two high-capacity abattoirs, six pooled fecal samples (n, 10 per pool) were collected from each transport trailer immediately after pigs were unloaded. Holding pens were sampled (one drinking water sample and six pooled floor samples consisting of swabs, residual liquid, and feces) prior to entry of study pigs for the routine holding period ( approximately 2.5 h). After slaughter, cecal contents and ileocecal lymph nodes were collected, on the processing line, from 30 pigs in each studied group. All samples were cultured for the isolation and identification of S. enterica by primary enrichment in GN-Hajna and tetrathionate broths, secondary enrichment in Rappaport-Vassiliadis broth, and plating on brilliant green sulfa and xylose-lysine-tergitol-4 agars, followed by biochemical and serological identification. The study pens were highly contaminated with S. enterica; all holding pens sampled had at least one positive sample. Additionally, 33% (8 of 24) of drinking water samples were positive for S. enterica. All 24 groups of pigs had S. enterica-positive cecal contents and ileocecal lymph nodes, including those groups from transport trailers with no positive samples. From pigs, trailers, and pens, 586 isolates representing 36 different Salmonella serovars were isolated. Of the 353 isolates from pigs (109 from ileocecal lymph nodes plus 244 from cecal contents), 19% were identified as belonging to the same serovars as those isolated from the respective pens; 27% were identified as belonging to the same serovars as those isolated from the trailers. Sixteen percent of the unique serovars were isolated from both pigs and pens, suggesting that pens served as the infection source. This study demonstrates highly contaminated abattoir holding pens and watering sources. It also demonstrates that holding pens can serve as an infection source. This study identifies the abattoir holding pens as a significant hazard and a potential control point for Salmonella contamination in the preharvest pork production chain.

/pdf/preslaughter-holding-environment-in-pork-plants-is-highly-wqdmb766qk.pdf

Preslaughter holding environment in pork plants is highly contaminated with Salmonella enterica

Pre-harvest risk factors for Salmonella enterica in pork production ☆

https://vetmed.iastate.edu/sites/default/files/labs/Food_Risk_Modeling_and_Policy_Lab/Rostagno%202006.pdf

Salmonella Prevalence in Market-Age Turkeys On-Farm and at Slaughter

Recent research has shown that much preharvest Salmonella entericainfection in pigs occurs immediately before slaughter during this rest period in the contaminated abattoir holding pens. The objective of this study was to evaluate a potential intervention strategy to reduce the prevalence of S. enterica‐positive pigs at slaughter, which consisted of resting pigs prior to slaughter on their transport vehicle, instead of in the abattoir holding pen. Additionally, the effect of transportation of pigs from farm to the abattoir on S. enterica prevalence was investigated. A total of 120 animals were included in the experiment, divided in four replicates (n 5 30 pigs per replicate). Fecal samples were collected from each animal at the farm and at the abattoir, where 15 randomly chosen pigs were unloaded and moved to a holding pen, while the remaining 15 pigs stayed in the transport trailer. After approximately 1.5 h of resting, both groups were slaughtered. Samples collected included distal ileum portion, cecal contents, and ileocecal lymph node. The overall S. enterica prevalence (pigs positive in at least one of the samples collected at slaughter) was higher for pigs held in the abattoir pens (40.7% versus 13.3%, P , 0.05). There was no difference (P . 0.05) for the S. enterica prevalence before and after transportation from farm to abattoir (5.8% versus 0.8%, respectively). This study demonstrates that resting pigs on the transport vehicle has the potential to decrease S. enterica levels entering the abattoir. Food safety is a defining issue in the global pork market, and Salmonella entericais of great concern for the pork production industry. Although the S. enterica contaminating the slaughter and processing line in the abattoirs originates from the production farms, the perimarketing portion of the production chain (particularly, the preslaughter holding) has been demonstrated to constitute a putative factor for the carriage of S. enterica into the abattoirs (9, 15, 17). Prior to slaughter, pigs are held for a period of time to recover from the physiological changes attributed to transport, improve meat quality, and maintain a constant supply for the slaughter line (3, 20). However, we have demonstrated (7, 9, 15) that (i) abattoir holding pens are highly contaminated with S. enterica, (ii) swine exposed to a S. enterica‐contaminated environment can become rapidly infected, and (iii) much of the preharvest S. enterica infection in pigs occurs immediately before slaughter during this rest period in the contaminated abattoir holding pen. Consequently, at slaughter, the intestinal tract of the pigs and its associated lymph nodes are frequently contaminated or infected with S. enterica and provide the main source from which the bacteria may be spread in the abattoir, contami

Marcos H. Rostagno

Papers

Impact of Heat Stress on Poultry Production

Preslaughter holding environment in pork plants is highly contaminated with Salmonella enterica

Pre-harvest risk factors for Salmonella enterica in pork production ☆

Salmonella Prevalence in Market-Age Turkeys On-Farm and at Slaughter

Research Note Resting Pigs on Transport Trailers as an Intervention Strategy To Reduce Salmonella enterica Prevalence at Slaughter