Browsing by Subject "Salmonella"
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Item A Case Study and Framing Analysis of the 2008 Salmonella Outbreak(Texas Tech University, 2009-08) Irlbeck, Erica; Akers, Cindy; Baker, Matt; Brashears, Mindy M.; Burris, Scott; Duemer, Lee S.In April 2008, the United States Food and Drug Administration began investigating a potential Salmonella outbreak in Texas in New Mexico. Initially, tomatoes were the suspected carrier of the pathogen; however, after three months of investigation, the FDA determined jalapenos grown in Mexico were the culprit. Tomato growers across the United States reported losses of $250 million. The purpose of this study was to examine television news coverage of the Salmonella outbreak through a case study using framing theory in order to gain an understanding of how reporters’ ideologies, attitudes, and corporate pressures influenced the frames that were reported on the ABC, CBS, and NBC news networks. A qualitative case study using interviews with reporters and content analysis was used to investigate the research questions. The reporters revealed they supported the farmers, they wanted change within the FDA, and they had confidence in the U.S. food supply. The frames presented in the television news coverage were health risk, financial impact, devastation of tomato growers, and frustration with the FDA. The frames that were built by reporters’ inputs were devastation of the tomato grower and frustration with the FDA. This dissertation concluded that in some instances, television news frames are influenced by the reporters’ attitudes and ideologies, and in other instances, they are not.Item A case study of the risk and crisis communications used in the 2008 Salmonella outbreak(2010-12) Palmer, Ashley; Irlbeck, Erica; Meyers, Courtney; Chambers, ToddThe Salmonella outbreak of 2008 was one of the largest ever foodborne illness outbreaks to impact the produce industry. Tomatoes were initially pinpointed as the source of the outbreak. Eventually, the FDA was able to trace the outbreak to imported jalapeño peppers, but the find came too late to recover the $100 million losses for the tomato industry. The purpose of this study was to examine the risk and crisis communication efforts taken by public relations practitioners in the produce industry during the 2008 Salmonella outbreak to determine which efforts were successful and which were ineffective. This qualitative case study used the interviews of nine public relations practitioners in the tomato industry to collect the information needed to fully explore the research objectives of the study. The study found that all of the public relations practitioners attempted to communicate effectively with their audiences despite the negative nature of the 2008 Salmonella crisis. Additionally, the practitioners revealed their thoughts and perceptions about the outbreak, the media, and the communications used during the outbreak, which provided valuable insight into the communication efforts of an organization during a crisis. The study concluded with a list of effective and ineffective communication efforts gathered from the responses of the interviewed practitioners that will serve as the basis for a risk and crisis model to be developed and used in the future.Item A case study of the risk and crisis communications used in the 2009 salmonella outbreak in peanut products(2012-05) Fry, Jessica; Irlbeck, Erica; Meyers, Courtney; Chambers, ToddCrisis management is a tool designed to fight a crisis; minimize the inflicted damage; and protect the organization, stakeholders, and industry from harm. Crisis management processes include preventative measures, crisis management plans, and post-crisis evaluations (Coombs, 2010a, 2007b). The 2009 Salmonella outbreak in peanut products was the second outbreak caused by contaminated peanut butter and created a period of negative publicity for the food and peanut industry. It was one of many large food outbreaks that the United States has seen in the past six years, all of which negatively impacted the food industries and agriculture. The public assumed that tainted peanuts might have entered into peanut butter and other food items (Smith, 2009). It is important for the various channels of distribution and public relations practitioners in the food and agriculture industry to be able to work together to uphold the strong reputation of the organization and agriculture in the midst of a crisis. Public relations practitioners worked to communicate with consumers to increase their confidence in the peanut industry. Organizational crisis communication messages play a vital role in crisis situations; they provide information for those affected by the crisis and assist in reducing the damage and impact of the crisis on the organization (Coombs, 2010b; Fediuk, Coombs, & Botero, 2010).Item A comparison of diagnostic techniques for detecting salmonella spp in equine fecal samples using culture methods, gel-based pcr, and real-time pcr assays(Texas A&M University, 2007-09-17) Smith, Shelle AnnSalmonellae are enteric bacteria infecting animals and humans. Large animal clinics and Veterinary Teaching Hospitals are greatly affected by Salmonella outbreaks and nosocomial infection. The risk of environmental contamination and spread of infection is increased when animals are confined in close contact with each other and subjected to increased stress factors. This study was designed to compare double-enrichment culture techniques with Gel-based and Real-time PCR assays in the quest for improved diagnostic methods for detecting Salmonella in equine fecal samples. 120 fecal samples submitted to the Clinical Microbiology Laboratory of the Veterinary Medical Teaching Hospital at Texas A&M University (CML, VMTH, TAMU) were tested for Salmonella using all three techniques. Double-enrichment bacterial culture detected 29 positive results (24%), Real-time PCR detected 33 positive results (27.5%), and Gel-based PCR detected 73 positives results (60.8%). While culture and real-time PCR methods had similar results, the gel-based PCR method detected many more positive results, indicating probable amplicon contamination. Real-time PCR can be completed as soon as the day after submission while culture techniques may take 2 to 5 days to complete. However, viable bacterial cells are needed for antimicrobial susceptibility testing and serotyping: both important for epidemiological studies. Therefore, double-enrichment bacterial culture performed concurrently with real-time PCR methods could be efficient in clinical settings where both accurate and expedient results are required.Item Application of antimicrobial treatments in a commercial simulation to reduce E. coli O157:H7 and Salmonella spp. in beef trim and in ground beef(2006-12) Harris, Deidrea D.; Miller, Markus F.; Brashears, Mindy M.; Brooks, Chance J.Pathogens are of great concern for processors for food safety issues and for economic reasons. While beef trimmings and ground beef are to be cooked by the consumer, the processor must recall the raw product if testing indicates the presence of Escherichia coli O157:H7. Processors have very few interventions for beef trimmings and ground beef. A limited amount of research has been completed to determine antimicrobial effects under commercially simulated conditions on beef trim to reduce pathogens. The objective of this study was to validate the effectiveness of acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water in reducing pathogen levels in beef trim prior to and after grinding in a simulated processing environment utilizing a belt turning and spray application. The effectiveness of these interventions on Escherichia coli O157:H7 and Salmonella Typhimurium were determined prior to treatment and at the following processing points: 1) just after treatment (20 minutes); 2) just after grind (6 hours); and 3) 24 hours after anaerobic storage at 4°C. Trim was inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium, with an inoculation level of 1x105 cfu/g. Sensory preparation was similar to the experimental design above except none of the trim was inoculated with pathogens. The organoleptic properties were evaluated during short term refrigerated storage at 6 and 24 hours after preparation. Raw patties were packaged on a Styrofoam tray and displayed in a retail display case. Visual panelists were trained to determine beef color, color uniformity, percentage of discoloration and browning evaluations of the raw patties based on appearance and composition. Muscle luminance, redness and yellowness of the raw product were objectively measured using the Minolta Spectrophotometer. Triangle test were used for comparison of the control and treated samples at 6 and 24 hours after production. Panelists (n = 24) were given three coded samples, including two of the same sample and one odd sample. Panelists were asked to determine the odd or different sample. Results from this study indicate that all antimicrobial interventions, including sterile water, reduced pathogen loads (P < 0.05) for both Escherichia coli O157:H7 and Salmonella Typhimurium in ground beef by almost 1 log cycle. The antimicrobial treatments of: sterile water, 5% lactic acid, 2% acetic acid, 5% acetic acid, and acidified sodium chlorite (1000 ppm) significantly reduced Escherichia coli O157:H7 (P < 0.05) in ground beef. The antimicrobial treatments of: acetic and lactic acids (2% and 5%), acidified sodium chlorite (1000 ppm), and sterile water significantly reduced pathogen loads of Salmonella Typhimurium (P < 0.0001) in ground beef 6 and 24 hours after processing. Utilizing a triangle test there was no significant difference P < 0.05 in the mean of correct responses between controls, 2% lactic acid, 5% lactic acid, 2% acetic acid, 5% acetic acid and acidified sodium chlorite (1000 ppm) within treatment, 6 or 24 hours samples from a non-trained sensory panel.Item Attachment of Salmonella on cantaloupe and effect of electron beam irradiation on quality and safety of sliced cantaloupe(Texas A&M University, 2006-04-12) Palekar, Mangesh PrafullIncrease in consumption of fresh produce over the past decade has resulted in a rise in incidents of foodborne outbreaks due to pathogens. Chemical sanitizers have been extensively used in the industry for decontamination of fresh produce. However, they are ineffective in certain commodities and under certain processing conditions, necessitating the evaluation of alternative technologies. Electron beam irradiated sliced cantaloupe were tested for 21 days of storage for total aerobic bacterial counts, texture, color and sensory parameters as a function of irradiation doses 0, 0.7 and 1.4 kGy and the wash treatments, water and 200 mg/L chlorine applied to the melons before cutting. Melons washed only with water prior to cutting had total aerobic bacterial counts of 4.0, 2.0 and 0.8 log cfu/g on day 0 at irradiation doses of 0, 0.7 and 1.4 kGy respectively. On day 0, melons washed with chlorine prior to cutting had total aerobic bacterial counts of 2.7, and 0.7 log cfu/g at irradiation doses of 0 and 0.7 kGy and below detection limit at 1.4 kGy. Texture measured as compression force was lower only for cantaloupe irradiated at 1.4 kGy. Irradiation did not affect objective color and descriptive attribute flavor and texture sensory attributes of cantaloupe. Irradiation reduced Salmonella Poona by 1.1 log cfu/g at 0.7 kGy and 3.6 log cfu/g at 1.5 kGy. The D-value of S. Poona on irradiated sliced cantaloupe was found to be 0.211 kGy. Among the spoilage organisms, lactic acid bacteria and mold were reduced effectively by irradiation but there was no significant effect on reduction of yeasts. Our results show that electron beam irradiation in combination with chemical sanitizers is effective in decontamination of fresh-cut produce. Electron microscopy images provided valuable information on attachment sites of S. Poona on cantaloupe rind. The ineffectiveness of chemical sanitizers due to possible inaccessibility to pathogens in these attachment sites provides the basis for application of irradiation in decontamination of fresh produce.Item Baseline of salmonella prevalence in retail beef and produce from Honduras and Mexico(2012-08) Maradiaga, Martha; Brashears, Mindy M.; Miller, Markus F.; Thompson, Leslie D.Salmonella is a common cause of food-borne illness worldwide, especially with must recent outbreaks. The sources of these outbreaks include contaminated animal products, including raw or undercooked meat as well as contaminated produce. The objective of the current study was 1) to develop a baseline for the prevalence and identification of Salmonella in beef and produce in Honduras, and produce in Mexico; and 2) to identify Salmonella serotypes in both Honduras and Mexico. A total of 393 retail whole muscle beef cuts samples and 383 produce samples (cantaloupes, cilantro, cucumbers, leafy greens, peppers, and tomatoes) were collected from major cities in different regions in Honduras in 4 different trips. A total of 514 produce samples were collected from major cities in Mexico in 6 different trips. Produce types and analysis followed the same as in Honduras. All retail beef and produce samples were tested using the BAX® System PCR Assay for Salmonella detection, with positive samples isolated for Salmonella using traditional cultural methods. Positive isolates were agglutinated and prepared for serotyping. Overall, the prevalence of Salmonella-positive samples in Honduras (N = 393) retail beef resulted in 5.9% with a 95% CI [3.9, 8.7]. Whereas positive beef carcass swabs was 7.8% in both beef plants in Honduras (11/141). The most common serotypes identified in Honduras were Salmonella serotype Typhimurium followed by Salmonella serotype Derby. The overall prevalence of Salmonella in Honduras produce (N 383) was 2.4% with a 95% CI [1.2, 4.5]. Overall, the prevalence of Salmonella-positive samples in Mexico (N = 514) produce resulted in 2.1% with a 95% CI [1.2, 3.8]. The most common serotype identified in Mexico was Salmonella serotype Meleagridis. Other serotypes found in Mexico were Typhimurium, Kentucky, and Newport.Item The c-di-GMP binding protein, YcgR, is the primary inhibitor of motor function in Salmonella and Escherichia coli.(2013-12) Nieto, Vincent Michael; Harshey, Rasika M.E. coli and Salmonella enterica have multiple c-di-GMP cyclases and phosphodiesterases. Absence of a specific phosphodiesterase YhjH impairs motility in both bacteria. yhjH mutants have elevated c-di-GMP levels and require YcgR, a c-di- GMP-binding protein, for motility inhibition. This study demonstrates that YcgR interacts with the flagellar switch-complex proteins FliG and FliM, with the primary interaction site located within FliM. Interaction of YcgR with these proteins induces a CCW motor bias and reduces the efficiency of torque generation, thus inhibiting both chemotaxis and the speed of movement. In collaboration with David Blair’s group at the University of Utah, we propose a "backstop brake" model showing how both effects of YcgR on the motor can result from an initial disruption of the FliM/FliG interface, followed by destabilization and disorganization of the FliG C-terminal domain, which interacts with the stator protein MotA. Support for this order of events i.e. induction of a CCW bias followed by reduction of torque, is provided for S. enterica motors. Data from single motor analysis show that E. coli and S. enterica motors have inherently different properties, but that YcgR is solely responsible for disruption of motor function in both bacteria. This study also finds that E. coli and S. enterica employ c-di-GMP in additional and different pathways to impede motility. Inhibition of motility and chemotaxis may represent a bacterial strategy to prepare for sedentary existence by disfavoring migration away from a substrate on which a biofilm is to be formed.Item Challenges of Pathogen Control in Beef Cattle Production and Processing in South Texas(2013-01-04) Haneklaus, Ashley NThis multi-phase project was designed (1) to evaluate existing post-harvest process controls and intervention strategies used to reduce Escherichia coli O157:H7, (2) to evaluate the impacts of cattle source and environmental factors on Salmonella prevalence in bovine lymph nodes, and (3) to evaluate sanitary conditions of feedyards in South Texas. The ultimate goal of this project was to identify and implement measures that reduce E. coli O157:H7 in beef harvest facilities, and Salmonella prevalence in feedyards. To evaluate process control of E. coli O157:H7 throughout the beef harvest process, samples were collected from harvest floor processing areas at two commercial beef slaughter establishments, and enumerated for aerobic plate counts, E. coli/coliform, and Enterobacteriaceae. To survey existing Salmonella prevalence, bovine lymph nodes (n = 307) were collected from beef carcasses at a commercial beef processing plant. Lymph nodes were extracted from cattle sourced from seven feedyards. Salmonella prevalence in lymph nodes was found to be 0% in cattle sourced from only one of the seven yards. Lymph nodes from cattle sourced from the other feedyards yielded positive samples, with varying prevalence. Of the remaining six feedyards, one feedyard yielded 88.2% prevalence of Salmonella in bovine lymph nodes, which was significantly higher than all other feedyards (42.9, 40.0, 40.0, 24.0, and 4.0%). The prevalence of Salmonella in the feedlot environment was compared among three feedyards; one yard had 65.0% environmental prevalence of Salmonella, which was statistically higher than the other feedyards surveyed. Of the two remaining yards, one had 0% prevalence of Salmonella in fecal and soil samples, which was also the feedyard with 0% prevalence of Salmonella in lymph nodes. Findings include (1) the significance of effective sanitary dressing procedures and intervention strategies in a beef harvest environment, (2) that there is clear feedyard-to-feedyard variation with relation to Salmonella prevalence in bovine lymph nodes, and (3) that differences in environmental factors existed among feedyards although the reasons remain unclear.Item Common messenger molecules and cell types demonstrating neuroendocrine-immune interactions in the chicken(Texas A&M University, 2006-08-16) Oubre, Cherie MorganThe aim of this study was to identify common messenger molecules used in both the immune and the neuroendocrine systems in birds, and to shed light on a cell type within the bursa of Fabricius that has historically been postulated as a potential neuroendocrine-immune link, the bursal secretory dendritic-like cells (BSDC). An immunocytochemical approach was used to identify neuroendocrine cell populations in the thymus, pituitary and bursa of Fabricius in the chicken. Molecular confirmation of the neuroendocrine cell marker, chromogranin A (CgA) in the thymus tissue of the chicken was reported. Previously the serine protease inhibitor, ovoinhibitor, was localized in bursal follicles, specifically the cortico-medullary border region. The presence of ovoinhibitor was identified and confirmed in the chicken pituitary by this study. Continued focus on the neuroendocrine-immune interactions in chicken immune tissue narrowed the study around the BSDC population. The BSDC are a component of the stromal, non-lymphoid cellular environment of the bursa of Fabricius and are thought to play a role in B-cell maturation and differentiation. They are located mainly along the cortico-medullary border of the bursal follicles in the same area as the majority of the ovoinhibitor-positive cell population. During attempts to isolate the BSDC population by flow cytometry and laser capture microdissection, a cell culture method was developed that enriched the BSDC population by 10-fold. This enriched population was used to evaluate protein product secretion following lipopolysaccharide (LPS) challenge and compared to in vivo challenge with live Salmonella. For the first time, up-regulation of the pro-inflammatory cytokine IL-12 was documented in the chicken following in vivo challenge. In addition, the gene expression of serine protease inhibitors was markedly decreased in the adherent cell population following LPS stimulation. As a result of this research a novel method for the enrichment of an adherent population, including the BSDC, was developed, providing a valuable tool for the analysis of this population during immune stimulation.Item Comparative Analysis of Live, Heat-inactivated, and Electron Beam Inactivated Salmonella Typhimurium Infection in Human Host Cells(2013-08-07) Corkill, CarolinaSalmonella Typhimurium continues to be a leading cause of human gastroenteritis worldwide. This organism is a facultative intracellular pathogen, meaning that it is able grow and reproduce within the host cell it inhabits. S. Typhimurium has the ability to invade and replicate within human intestinal epithelial cells, which in turn causes induced cell death or apoptosis. The human intestinal epithelial cells, HCT-8, were challenged with live, heat inactivated, and electron beam inactivated S. Typhimurium for various time points. Infected cell monolayers were collected for RNA extractions, and Real-time PCR was performed on the samples to analyze differential gene expression. Genes of the host cell that were expected to be differentially expressed were shortlisted and Real-Time PCR analysis was performed. Internalized Salmonella within the host cell was unable to be successfully visualized using fluorescent light microscopy. However, differential gene expression for a common transcriptional regulator and inflammatory chemokine were observed to be expressed significantly higher in response to e-beam inactivated Salmonella infection. Genes coding for extracellular and intracellular pattern-recognition receptors of the host cells were shown to be up-regulated in response to e-beam inactivated Salmonella infection at 4 and 24 hours, but were not statistically significant. Additional studies must be conducted to definitively confirm e-beam irradiated Salmonella has the ability to invade human host cells.Item Comparison of cecal colonization of Salmonella enterica serotype Typhimurium in white leghorn chicks and Salmonella-resistant mice(2009-05-15) Sivula, Christine PatriciaSalmonellosis is one of the most important bacterial food borne illnesses worldwide. Among the many Salmonella serotypes, Typhimurium is the most commonly implicated serotype in human disease in the United States. A major source of infection for humans is consumption of chicken or egg products that have been contaminated with S. Typhimurium. The breadth of knowledge regarding colonization and persistence factors in the chicken is small when compared to our knowledge of factors that are important for these processes in other species used in Salmonella research, such as cattle and mice. Defining the factors important for these processes in the chick is the first step in decreasing the transmission of Salmonella between animal and human hosts. In this work, we developed a chicken model to identify and study intestinal colonization and persistence factors of Salmonella enterica serovar Typhimurium. We studied the degree of enteric and systemic colonization of wild type S. Typhimurium ATCC14028, one of the most widely studied Typhimurium isolates, in White Leghorn chicks and in Salmonella-resistant CBA/J mice during infection. Furthermore, we determined the distribution of wild type S. Typhimurium and a SPI-1 mutant (invA) during competitive infection in the cecum of 1-week-old chicks and 8-week-old mice. Cell associated, intracellular and luminal distributions of these strains in the cecum were analyzed as total counts in each compartment and also as a competitive index. Localization of S. Typhimurium ATCC14028 and the role of SPI-1 in colonization are well studied in murine models of infection, but comparative infection in chicks with the same strain has not been undertaken previously. We show that the cecal contents are the major site for recovery of S. Typhimurium in the cecum of 1-week-old chicks and Salmonella-resistant mice. We also show that while SPI-1 is important for successful infection in the murine model, it is important only for cell association in the cecum of 1-week-old chicks. Finally, we found that in chicks infected at 1 week of age, bacterial counts in the feces do not reflect those seen in the cecum as they do in mice.Item Comparison of Current Almond Pasteurization Methods and Electron Beam Irradiation as an Alternative(2012-02-14) Cuervo Pliego, MaryTwo outbreaks of salmonellosis were linked to the consumption of raw California almonds in 2001 and 2004. Current federal regulations mandate that all almonds grown in California are to be treated with a process that results in a 4-log reduction of Salmonella. Since four out of the five approved technologies to pasteurize almonds rely on the application of heat to control Salmonella, the evaluation of alternative technologies against heat resistant Salmonella Senftenberg was imminent. In this study, almonds that were inoculated with S. Enteritidis PT 30 and S. Senftenberg, were treated with electron beam irradiation (e-beam), blanching and oil roasting. The thermal death time (D-value) for S. Enteritidis PT 30 when treated with e-beam was 0.90 kGy, 15 s when subjected to blanching at 88 degrees C, and 13 s when treated with oil at 127 degrees C. Irradiation and thermal resistance of S. Senftenberg was not significantly different (P > 0.05) from S. Enteritidis PT 30. The commercial application of e-beam as a pathogen intervention was assessed through Monte Carlo simulations (MCS) and experimental measurements. The sensory characteristics of almonds commercially treated by e-beam, blanching and roasting were assessed by a consumer panel. Irradiated and blanched almonds did not differ in consumer overall like (P > 0.05). Bitterness and rancidity attributes of irradiated almonds were between a "dislike slightly" and "dislike moderately", whereas blanched and roasted almonds were between "neither like nor dislike" and "like slightly". Almonds commercially irradiated, blanched and roasted were subjected to an accelerated shelf-life test (ASLT) evaluating percentage free fatty acids, peroxide value, and 2-thiobarbituric acid reactive substances (TBARs). No clear differences between treatments were observed at any given point in time in any of the chemical tests. A gas chromatography-mass-spectrometry-olfactometry (MDGC-MS-O) technology was used to compare full aroma and flavor profiles from raw and e-beam irradiated almonds. Differences in the aroma/odor profile and the taste analysis revealed that the difference between raw and irradiated almonds is extremely subtle. In conclusion, e-beam may be a feasible technology to control Salmonella in almonds if used at low doses, as a part of a series of interventions.Item Controlling Salmonella in Poultry using Bacteriophages(2012-10-19) Sanchez Pena, AnaPublic health concerns associated with high prevalence of foodborne salmonellosis, the emergence of antibiotic-resistant organisms and the identification of poultry meat and products as one of the most common sources of Salmonella support the need for new pathogen control strategies in the poultry industry. Scientific research has focused on the use of bacteriophages as therapeutic agents for humans and animals; however, limited studies have been conducted on bacteriophage application on food safety, especially on poultry. Therefore, the objective of this study was to evaluate the phage density and exposure time required to reduce Salmonella load on experimentally inoculated chicken meat. In Experiment 1, serovars of Salmonella were tested for antimicrobial susceptibility and rifampicin-resistant isolates were generated. Cocktails of the serovars Enteritidis, Kentucky and Typhimurium (EKT), and Hadar and Heidelberg (HH), were inoculated on chicken breast samples to a target of 104 CFU/g. A mixture of three lytic bacteriophages, active against multiple Salmonella serovars was applied to chicken samples. A total of 84 samples (25 +/- 2 g) per each cocktail were distributed among a negative control, Salmonella-inoculated positive control, Salmonella-inoculated samples treated with the phage mixture at differing titers (105, 106, 107, 108, and 109 PFU/ml) with two identical samples at 0, 15, 30, 60, 120, 360 min at 4 degrees C. Experiment 2 evaluated nalidixic acid-resistant Salmonella Typhimurium among negative control, Salmonella-inoculated control (positive control), Salmonella with two phage titers (105 and 109 PFU/ml) at 0, 30, 60 and 120 min at 25 degrees C and 4 degrees C. Results showed differences in means for Salmonella cocktail EKT ranged from 0.1 to 0.7 log10 CFU/g with 0.7 log10 for 108 PFU/ml, 30 min, 4 degrees C. For Salmonella cocktail HH, reductions ranged from 0.1 to 0.4 log10 CFU/g with 0.4 log10 on samples treated with 108 PFU/ml, 120 min, 4 degrees C. For the Experiment 2, a higher phage concentration (109 PFU/ml) at 120 min post-inoculation storage at 25 degrees C was required to yield a 0.9 log10 difference in means. These findings showed that higher concentrations of bacteriophage were more effective controlling Salmonella than lower ones at both temperatures. In addition, temperature, time and bacterial attachment may influence phage efficacy.Item DETERMINING THE PREVALENCE OF SALMONELLASanders, Shanequa GeNey; Branham, Loree A.; Braden, Kirk W.; Wright, Andrew P.; Pate, Sandra K.Experiment one’s objective was determining prevalence of Salmonella in small ruminants, their carcass and products. Experiment two’s objective was to validate a commercial PCR system for Salmonella detection in fecal and hide samples. Goat and lamb carcass swabs were collected pre-evisceration (n=66), post-evisceration (n=70) and post-intervention (n=70). Hide swabs (n=103) and fecal samples (n=102) were aseptically retrieved. Samples were analyzed for Salmonella using Chi-square and McNemar’s statistics were performed using SAS. Salmonella was found in 22.55% of fecal, 17.48% of hide, 7.81% of pre-evisceration, 5.71% of post-evisceration, 1.43% of post-intervention and 18.18% of products. Results show real-time PCR systems are reliable detection methods for fecal and hide samples. Analysis of concordance showed substantial agreement beyond chance between the two methods when analyzing fecal samples (Kappa=0.65). Almost perfect agreement beyond chance between the two methods was detected when analyzing hide samples (Kappa=0.84).Item Effect of Accelerated Drying on the Reduction of Salmonella on Almonds by Thermal and Electron Beam Irradiation Pasteurization Treatments(2013-08-08) Mohammed, Zahra HassanAfter two outbreaks of salmonellosis that were linked to the consumption of almonds in 2001 and 2004, scientific community and industry have encouraged the study of pathogen inactivation kinetics in almonds. However, these studies often have overlooked the increase of water resulting from the inoculation of almonds. This increase of free water may result in data that may be overestimating the final outcome of treatments applied to pasteurize almonds in industrial settings. Therefore, in 2011 a study of almonds was performed at Texas A&M University to determine whether there was a need for Aw restoration. In this study, the effect of accelerated drying on the reduction of Salmonella on almonds was investigated, Salmonella Entritidis PT 30 isolated from one of the outbreaks linked to almonds, and Salmonella Typhimurium LT2 were used. For irradiation, the effect of vacuum packaging and air packaging on the sensitivity of Salmonella to e- beam irradiation was evaluated for both accelerated drying and conventional drying. The D value for Salmonella Entritidis PT 30 when treated with blanching at 88?C with accelerated drying was 10.7? 0.1 s, and 12.8 ? 0.3 s with conventional drying. When subjected to oil roasting at 127?C, the D values were 10.5 ? 0.1 s with accelerated drying, and 10.2 ? 0.2 s with conventional drying. For irradiation treatments, the D10 value for vacuum packaged almonds was 0.35 ? 0.02 kGy with accelerated drying, and 0.38 ? 0.04 kGy with conventional drying. When irradiated in the presence of air, the D10 value of Salmonella was 0.26?0.04 kGy for almonds with accelerated drying, and 0.29 ? 0.03 kGy conventional drying. In conclusion, the accelerated drying process resulted in greater reduction in Salmonella on almonds in comparison to conventional drying when subjected to blanching but no differences were found for oil roasting (P > 0.05). For e-beam irradiation the D_10 values were significantly greater (P < 0.05) for vacuum with accelerated drying than for Air almonds with accelerated drying. This indicates that if a process applied in the industry were to be developed based on challenge studies when conventional drying was achieved, the almonds might likely be subjected to a treatment that is stronger than necessary to achieve pasteurization.Item Effect of heat shock on hilA expression in Salmonella Typhimurium(Texas A&M University, 2005-02-17) Churi, Asawari ShreeniwasThe effect of heat shock was observed on the expression of hilA in Salmonella Typhimurium by creating a fluorescence-based reporter strain of Salmonella and by realtime reverse transcriptase polymerase chain reaction (RT-PCR). The hilA gene in Salmonella is known to play an important role in its pathogenesis. hilA is known to be activated when the bacteria encounter stress-inducing conditions. A number of factors have been identified that affect hilA expression, such as, pH, osmolarity, oxygen tension. When Salmonella enter their warm-blooded hosts, they encounter an increase in temperature. Therefore, heat is another stressor that is encountered by Salmonella during infection of their hosts. A fluorescence-based strain of Salmonella was created to study the effect of heat shock. The gene for green fluorescent protein (gfp) was placed under the control of the promoter of hilA on a plasmid. This plasmid was used to transform Salmonella cells to create a fluorescent strain. In this strain, when the hilA promoter is activated, gfp is transcribed, which encodes the green fluorescent protein. This protein can be measured by a fluorescence assay. The results of this study indicated that at 45?C, hilA is activated. RT-PCR was used to look at hilA expression at different temperature. The results of this study indicated that, compared to 37?C, higher temperatures like 45?C and 55?C significantly activate hilA.Item Effect of sanitizer treatments on Salmonella enterica serotype Poona on the surface of cantaloupe and cell transfer to the internal tissue during cutting practices(Texas A&M University, 2005-02-17) Vadlamudi, SasiIn recent years, due to the increasing number of produce-related outbreaks, greater attention has been given to interventions that remove human pathogens on fresh produce. Survival of Salmonella Poona on the surface and stem scar portions of inoculated cantaloupe, effect of chlorine or lactic acid or ozone on the survival of bacteria, transfer of pathogen from the rind to the fresh-cut tissue during cutting and growth and survival of Salmonella Poona on the fresh-cut tissues during 15 days of refrigerated storage were investigated. Preliminary studies were conducted to confirm that the rifampicin-resistant strain used in the study was indistinguishable from the parent strain of Salmonella Poona. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Cantaloupes were immersed in an inoculum containing rifampicicn-resistant strain of Salmonella Poona (107 CFU/ml) for 3 min and then dried for 12 h. The inoculated melons were washed with chlorine (200 ppm) for 3 min or lactic acid (2%) for 2 min or ozone (30 ppm) for 5 min and fresh cut tissues were prepared by peeling the rind and cutting into pieces or cutting the melon and removing the rind. Results obtained indicate that the levels of Salmonella Poona recovered were higher when the sample was obtained from the scar portion than the surface. Surface treatment with tap water or chlorine did not reduce Salmonella Poona. However treatment with lactic acid or ozone reduced the levels by 2.5 and 2.3 log10 CFU/cm2 respectively on the surface. Fresh-cut tissue prepared from melons sanitized with lactic acid resulted in less transfer during cutting and reached below detectable limits after 9 days of refrigerated storage. Cutting melons after peeling the rind was found effective in reducing the transfer of Salmonella Poona into the tissue in comparison with cutting of melons and removing the rind later. Thus these data suggest that treatment with lactic acid and ozone may be effective in reducing Salmonella from the surface of the cantaloupe where as lactic acid was effective in reducing the transfer from the surface to the flesh.Item Effects of Cytosine-phosphate-Guanosine Oligodeoxynucleotides (CpG-ODN) on vaccination and immunization of neonatal chickens(Texas A&M University, 2005-02-17) Barri, AdrianaThe objective of this investigation was to evaluate the effects of administering CpG-ODN to commercial strain chickens as a potential adjuvant to vaccination against Salmonella, Eimeria spp., and Newcastle disease virus, or immunization to bovine serum albumin (BSA). During Experiment 1, which evaluated the dual application of CpG-ODN and a Newcastle disease virus vaccine, in the first of three replicate trials, on day 28 of the experiment, animals in the Vaccine + CpG 1& 14 experimental group were observed to have the highest levels of (p<0.05) anti-NDV IgG in serum. These levels were elevated above levels in animals from all other experimental groups. This suggestion for an adjuvant effect associated with CpG-ODN administration was not supported in the remaining two trials of experiment 1. Experiment 2 evaluated the potential for CpG-ODN to adjuvant a commercial live oocyst coccidial vaccine when applied by an oral route to neonatal broiler chickens. Overall, when body weight gain during challenge, development of intestinal lesions, and anti-Eimeria IgG levels were evaluated, vaccine administration alone was demonstrated to provide the best measure of protection among animals in all experimental groups, including those receiving either CpG-ODN or Non CpG-ODN. Experiment 3 investigated the simultaneous administration of CpG-ODN or Non-CpG ODN and a commercially acquired Salmonella typhimurium vaccine to SCWL chickens. Similar to experiments 1 and 2, antigen specific IgG responses in serum and indices of protection against field strain Salmonella challenge were variable and inconsistent. Anti-BSA IgG levels were compared in broiler and SCWL chickens immunized against BSA by a drinking water route of administration alone, or in combination with two different concentrations of CpG-ODN or Non CpG-ODN in experiment 4. The only observation where CpG-ODN and BSA co-administration resulted in anti-BSA IgG levels that were elevated above BSA alone immunized chickens was measured in broilers at day 19 post-final immunization. Taken together, given the variable results reported in this investigation related to the co-administration of ODN and vaccine or protein antigen, these data are largely inconclusive for suggesting that CpG-ODN can effectively adjuvant humoral immune responses in commercial strain chickens.Item Effects of two-percent Ascophyllum nodosum supplementation on carcass characteristics, retail shelf-life, and prevalence of Escherichia coli O157:H7 and Salmonella spp. in feedlot steers(Texas Tech University, 2003-08) Braden, Kirk WayneDried brown seaweed, Ascophylium nodosum (ANOD) has decreased the prevalence of Escherichia coli 0157:H7 (EHEC) in animals fed 14d prior to harvest. Supplementation of ANOD has been shown to increase marbling (Allen et al 2001) and increase shelf life of beef steaks. Crossbred beef cattle (Bos indicus X Bos Taurus n=579) in a large commercial finishing facility were supplemented with 2% ANOD on a dry matter (DM) basis to determine effects on carcass merit, shelf-life and prevalence of EHEC and Salmonella spp. (SAL). Treatment (TRT n=400) animals received a steamrolled com base diet containing 2% ANOD, on a DM basis immediately following a 45d adjustment period at the finishing facility for a 14d period, and again 14d prior to harvest at the abattoir. Control (CON n=179) animals received steam-rolled com base diet at identical feeding periods. TRT and CON cattle were segregated into two harvest groups, harvest one (HI) and harvest two (H2) at feedlot per feedlot management practices. Both harvest groups consisted of TRT and CON cattle; with HI having 100 TRT and 100 CON and H2 consisting of 300 TRT and 80 CON. HI and H2 cattie were transported to harvesting facility (Excel Corporation, Plainview, TX) in close proximity to the finishing facility, and harvested at the conclusion of an 170 d and 177 d respective feeding period. Left carcass sides of all TRT and CON cattle from HI and H2 were retained after 36 h postmortem and evaluated for quality grade and yield grade (USDA, 1996) by trained Texas Tech University Meat Science personnel. Strip-loins (IMPS#180) and inside rounds (IMPS#168) were collected from each carcass side of cattle in HI group, vacuum packaged and transported to the Texas Tech University Meat Laboratory according to Montgomery et al. (2001). Vacuum packaged strip-loins and inside rounds were stored at 2°C until postmortem d 10. On postmortem d 10 strip-loins and inside rounds were removed from packaging and fabricated into three 2.54-cm steaks for sensory, Wamer- Bratzler Shear (WBS) force, and proximate analysis, and retail display. Strip-loins and inside rounds were then packaged for subsequent retail display analysis. All steaks for sensory, WBS, and proximate analysis were vacuum packaged and frozen at -26°C until a later date for determination. Hide swab and fecal samples (n=200) were obtained for EHEC and SAL evaluations according to AOAC (Association of Analytical Communities) approved microbiological assays from HI cattle. Animals were sampled (n=100 TRT, n-100 CON) one day prior (d-1) to feeding of ANOD and immediately following exsanguinations at the abattoir. Strip-loins and inside rounds were vacuum-packaged and stored at 2°C. At postmortem d 10, 17, 24, 31 and 38, strip-loins and inside rounds were removed from packaging and fabricated into 2.54-cm steaks. Following each fabrication day postmortem, the strip-loins and inside rounds were repackaged and stored at 2°C until the following postmortem time. After prescribed fabrication, steaks were over-wrapped with polyvinyl chloride film, subjected to simulated retail display at 2°C for up to 5d, and subjective color was evaluated daily by a trained panel. Prevalence of EHEC 0157 hide/fecal (P = 0.0001; P < 0.0001) and EHEC 0157:H7 hide/fecal (P < 0.0001; P < 0.0001) was significantly reduced from d-1 prevalence for TRT samples as compared to CON. Prevalence of SAL on hide swabs did not change for TRT (P = 0.64); however, CON animals exhibited an increase for SAL prevalence (P < 0.0001) from d-1 feeding levels. SAL prevalence increased for both TRT and CON fecal samples over d-1 levels (P = 0.002). However, TRT treatment samples exhibited a significantly lower post feeding prevalence of SAL for fecal samples as compared with CON. TRT animals exhibited higher marbling scores {P < 0.05) for HI group but exhibited no difference for H2 group. A number of effects such as final yield grade and preliminary yield grade were statistically significant and measurable in that regard; however, these effects were not biologically significant. There were no significant affects of treatment on sensory, shear or purge attributes when data were analyzed with the exception of inside round TRT steaks having a higher initial tenderness (P = 0.02) and lower off flavor score (P = 0.002) when compared to CON. Chemical analysis of strip-loin and inside round steak samples found that strip-loin TRT samples had a higher percentage of fat (P= 0.001), lower percentage of protein (P = 0.001), and no statistical difference in percent moisture (P = 0.43). Inside round samples exhibited a significant treatment affect for percent moisture (P = 0.03), but no affect on percent fat (P = 0.75) or protein (P = 0.09). TRT had no effect on lean color of strip-loin or inside round steaks. TRT improved color uniformity within PM l0d and 24d (P < 0.05). CON steaks from inside rounds and strip loins exhibited additional discoloration (P < 0.05) when compared to TRT steaks on retail display days 3, 4 and 5 within all postmortem aging periods. CON steaks exhibited increased lean browning on retail display day 5 of PM days 10, 17 and 24 when compared to TRT steaks (P < 0.05). Results from this study indicate that 2% ANOD supplementation in feedlot cattle diets significantly reduces EHEC and EHEC 0157:H7 prevalence, increases carcass merit and prolongs retail display shelf-life.