Meat Science Commons^™

Sensitivity Of Wild-Type And Rifampicin-Resistant O157 And Non-O157 Shiga Toxin-Producing Escherichia Coli To Elevated Hydrostatic Pressure And Lactic Acid In Ground Meat And Meat Homogenate, Abimbola Allison, Aliyar Cyrus Fouladkhah

Agricultural and Environmental Sciences Faculty Research

Various serogroups of Shiga toxin-producing Escherichia coli have been epidemiologically associated with foodborne disease episodes in the United States and around the globe, with E. coli O157: H7 as the dominant serogroup of public health concern. Serogroups other than O157 are currently associated with about 60% of Shiga toxin-producing E. coli related foodborne illness episodes. Current study evaluated sensitivity of the O157 and epidemiologically important non-O157 serogroups of the pathogen to elevated hydrostatic pressure and 1% lactic acid. Pressure intensity of 250 to 650 MPa were applied for 0 to 7 min for inactivation of strain mixtures of …

Effects Of Commercial Feed Additives On Growth Performance And Gut Microbiota Of Nursery Pigs, Xiaoyuan Wei

Graduate Theses and Dissertations

To secure animal welfare and maximum production, feed additives are often added to nursery pig diets to increase nutrition digestibility, enhance intestinal health, and prevent or mitigate disease, with the ultimate goal of improving growth performance. This thesis performed a longitudinal analysis using next-generation sequencing to investigate the dynamic changes of gut microbiota in weaned pigs fed commercial feed additives. Chapter II was used to evaluate the effects of organic acid mixture on growth performance and gut microbiota of weaning pigs. This study demonstrated that the inclusion of 0.035% (SBA0.035) or 0.070% (SBA0.070) sodium butyrate in a diet containing 0.5% …

Is Tb Testing Associated With Increased Blood Interferon-Gamma Levels?, Aideen E. Kennedy, Jim O'Mahony, Noel Byrne, John Macsharry, Riona G. Sayers

Department of Biological Sciences Publications

The Republic of Ireland reports a relatively low prevalence of Johne’s disease (JD) compared to international counterparts. Postulated reasons for this include a lower average herd size and a grass-based production system. Ireland also engages in high levels of bovine tuberculosis (bTB) testing. As interferon-gamma (IFN-γ) is believed to play a key role in protecting against JD, it is our hypothesis that administration of purified protein derivative (PPD), as part of the bTB test, is associated with a systemic increase in IFN-γ production, which may potentially limit clinical progression of the disease. We studied 265 cows (202 Friesian and 63 …

Detection And Quantitation Of Tetracycline Antibiotics In Agricultural Swine Wastes, Ali Jamal Abdulrheem

Masters Theses & Specialist Projects

The spread of tetracyclines through agricultural systems is causing the present bacteria to develop antibiotic resistance. The spread of this bacteria, as well as the tetracycline antibiotics in the environment is dangerous because these antibiotics pose health hazards for humans. The overuse of antibiotics, which are added to livestock feed, results in the antibiotics being released into the environment via animal feces. In this research, we have attempted to design an analytical method to isolate antibiotics from agricultural wastes with subsequent detection using liquid chromatography and mass spectrometry (LC-MS). The antibiotics investigated in this study were tetracycline, chlortetracycline, and oxytetracycline. …

A Tail Of Two Phages: Genomic And Functional Analysis Of Listeria Monocytogenes Phages Vb_Lmos_188 And Vb_Lmos_293 Reveal The Receptor-Binding Proteins Involved In Host Specificity, Aidan Casey, Kieran Jordan, Horst Neve, Aidan Coffey, Olivia Mcauliffe

Department of Biological Sciences Publications

The physical characteristics of bacteriophages establish them as viable candidates for downstream development of pathogen detection assays and biocontrol measures. To utilize phages for such purposes, a detailed knowledge of their host interaction mechanisms is a prerequisite. There is currently a wealth of knowledge available concerning Gram-negative phage-host interaction, but little by comparison for Gram-positive phages and Listeria phages in particular. In this research, the lytic spectrum of two recently isolated Listeria monocytogenes phages (vB_LmoS_188 and vB_LmoS_293) was determined, and the genomic basis for their observed serotype 4b/4e host-specificity was investigated using comparative genomics. The late tail genes of these …

Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares

Doctoral Dissertations

Emerging non-O157 Shiga toxin-producing Escherichia coli (STEC) were recently added to the zero tolerance policy by the USDA-FSIS. Therefore, the precise characterization of their thermal inactivation kinetics in different foods and the effect of stress on thermal inactivation are needed. This research aimed at determining the heat inactivation kinetics of non-O157 and O157 STECs in buffer and model food matrices and the effects of DnaK levels on thermal resistance after acid and heat-shock. Thermal inactivation was carried out in either in 2-ml glass vials or nylon vacuum-sealed bags for buffer and food (spinach, ground-beef, turkey deli-meat, pasta) samples, respectively. Vials …

Letter From The Dean, Lalit Verma

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

No abstract provided.

Delayed-Incubation Method For Microbiological Analysis Of Environmental Specimens And Samples, James S. Dickson, M. H. Brodsky, C. A. Davidson, M. J. Pettis, T. L. Tieso

James S. Dickson

Five laboratories compared the quantitative recovery of heterotrophic bacteria, yeasts and molds, coliforms, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus from a variety of naturally contaminated food and water samples, using traditional incubation procedures and a delayed-incubation method. Refrigeration of inoculated media for up to 3 days prior to incubation was shown to be a viable option for many quantitative analyses, but needs to be validated for each application. Some inoculated media withstood refrigeration for up to 7 days prior to incubation without any detrimental effect on the recovery of target cells, while the incubation of other media for similar …

Cell Surface Charge And Initial Attachment Characteristics Of Rough Strains Of Listeria Monocytogenes, James S. Dickson

James S. Dickson

The relative negative surface charge and hydrophobicity of four bacterial strains were evaluated by gravity flow and spin column methods. There was no significant difference between the two methods, indicating that spin column chromatography is an acceptable alternative method of determining cell surface charge or hydrophobicity. Six strains of Listeria monocytogenes which exhibited rough colony appearance were evaluated for surface charge and hydrophobicity and their ability to contaminate beef muscle tissue. With one exception, all of the rough strains exhibited greater net negative surface charge and reduced ability to contaminate beef during the initial stages of attachment. Since greater net …

Antimicrobial Effects Of Trisodium Phosphate Against Bacteria Attached To Beef Tissue, James S. Dickson, C. G. Nettles Cutter, G. R. Siragusa

James S. Dickson

Sliced beef tissue was artificially contaminated with Salmonella typhimurium, Listeria monocytogenes and Escherichia coli OI57:H7. The contaminated tissue was immersed in 8, 10 and 12% solutions of trisodium phosphate at 25, 40 and 55°C with contact times of up to 3 min. The concentration of the trisodium phosphate solution was not a significant factor in reducing the populations of the bacteria on either lean or adipose tissue. Reductions in bacterial populations of I to 1.5 loglocycles were obtained on lean tissue contaminated with the gram-negative pathogens, although less reduction in population was seen with L. monocytogenes. Greater reductions in bacterial …

Bacterial Starvation Stress And Contamination Of Beef, James S. Dickson, J. F. Frank

James S. Dickson

Salmonella typhimurium, Listeria monocytogenes, ad Escherichia coli 0157;H7 were starved by suspending washed cells in phosphate buffer for 5 days at 10, 25 or 37 degrees C. Starved bacteria were evaluated for their ability to attach to beef tissue and their sensitivity to acetic acid sanitizing. Starvation stress generally decreased the numbers of bacteria which attached to the tissue when compared to control bacterial cultures grown to late logarithmic growth phase. Starvation temperature was negatively correlated to the numbers of attached bacteria. Starvation slightly increased the sensitivity of attached S. typhimurium and L. monocytogenes cells to acetic acid, but did …

Isolation Of Listeria Spp. From Feces Of Feedlot Cattle, James S. Dickson, G. R. Siragusa, E. K. Daniels

James S. Dickson

Healthy feedlot beef cattle were surveyed for the presence of Listeria spp. in fecal grab samples taken over 3 months. Composite samples were made from 224 individual animals each month. Listeria monocytogenes was isolated from one composite sample (4%) from the first sampling and not from the subsequent two. Listeria innocua was found in composite samples from all three samplings at levels of 17, 9, and 35%, respectively. From the individual samples comprising the Listeria spp.—positive composites, L. monoytogenes was isolated from one sample (3%) in the second sampling but not in the first or third samplings. L. innocua was …

A Computer-Controlled Spray Chill Unit For Red Meat Carcasses, Maynard E. Anderson, James S. Dickson, Mark M. Hulse, Scott T. Drummond, John D. Crouse, Robert T. Marshall

James S. Dickson

A computer controlled and operated spray chill unit which can be used in future research studies for both spray chilling and decontamination of red meat carcasses is described. The unit consists of two parts: (1) an electromechanical system, and (2) a data acquisition/control system. Design concepts for the spray chill system are (1) versatility, (2) rapid change of spray parameters, and (3) computer control of the electromechanical system. An added feature is the computer data collection system for recording information related to each carcass (pH of muscle, surface and internal tissue temperatures, and weights of each half carcass during the …

Microbiological Decontamination Of Food Animal Carcasses By Washing And Sanitizing Systems: A Review, James S. Dickson, Maynard E. Anderson

James S. Dickson

Microbial contamination of animal carcasses is a result of the necessary procedures required to process live animals into retail meat. The contamination can be minimized by good manufacturing processes, but the total elimination of foodborne pathogenic microorganisms is difficult, if not impossible. A variety of methods have been developed to reduce the levels of contaminating bacteria on carcasses, although most of the current methods focus on washing and sanitizing procedures. The commonly used sanitizing agents include hot water, chlorine, and short-chain organic acids. The effectiveness of these compounds varies by the concentration used, the temperature of the sanitizers and contact …

Inhibition Of Listeria Monocytogenes On Beef Tissue By Application Of Organic Acids Immobilized In A Calcium Alginate Gel, James S. Dickson, Gregory R. Siragusa

James S. Dickson

Organic acids added to calcium alginate gels and immobilized on lean beef tissue inoculated with LLtetia monocytogenes (Lm) reduced the population significantly more than did acid treatment alone. Lactic acid (1.7% v/v) immobilized in alginate reduced counts by 1.3 log,, units vs 0.03 log unit decrease from the acid treatment alone. Acetic acid (2% v/v) reduced counts 1.5 and 0.25 log units, respectively. Over 7 days, Lm proliferated in samples without acid and/or alginate treatment. Differential counts on selective and non-selective agars indicated sublethal cellular injury occurred. Alginate coatings did not enhance acid inhibition on fat tissue. Immobilized agents may …

Acetic Acid Action On Beef Tissue Surfaces Contaminated With Salmonella Typhimurium, James S. Dickson

James S. Dickson

Beef tissue surfaces (lean and fat) were artificially contaminated with Salmonella typhimurium and then sanitized with 2% acetic acid. The reduction in bacterial population by the acid treatment was consistently proportional to the initial inoculum level for both tissue types. Increasing the amount of organic material in the inoculating menstra reduced the bactericidal effects of acetic acid on Salmonella typhimurium on fat tissue, although there was no change in effectiveness on lean tissue. Acid treatment sublethally injured about 65% of the population on both lean and fat tissue, and the residual effects of the acid resulted in a 1 log …

Control Of Salmonella On Beef Tissue Surfaces In A Model System By Pre- And Post-Evisceration Washing And Sanitizing, With And Without Spray Chilling, James S. Dickson, Maynard E. Anderson

James S. Dickson

Beef tissue was inoculated with a nalidixic acid resistant strain of Salmonella California and processed under conditions simulating pre- and post-evisceration carcass washing and sanitizing. These treatments, using distilled water to wash and 2% acetic acid to sanitize, reduced the population of salmonellae by as much as 2-log10 cycles when compared to samples which were washed only in distilled water. Increasing the acid temperature to 55°C reduced the bacterial populations further. Spray chilling, when used in series with the pre- and post-evisceration treatments, apparently resulted in recovery of some injured Salmonella.

Contamination Of Beef Tissue Surfaces By Cattle Manure Inoculated With Salmonella Typhimurium And Listeria Monocytogenes, James S. Dickson

James S. Dickson

Contamination of beef lean and fat tissue surfaces by Salmonella typhimurium and Listeria monocytogenes was evaluated using phosphate buffer or sterilized manure as an inoculation menstruum. Immersion in inoculated phosphate buffer resulted in an increase in numbers of attached cells during the 120 min inoculation for both bacterial species. Tissue immersed in inoculated manure generally showed an increase in cell numbers up to 10 min of immersion with only slight increases in cell numbers from lOto 120 min. Fewer cells attached to either tissue type from the manure inoculum (P<0.05), although actual numerical differences were small.

Attachment Of Salmonella Typhimurium And Listeria Monocytogenes To Glass As Affected By Surface Film Thickness, Cell Density, And Bacterial Motility, James S. Dickson, E. K. Daniels

James S. Dickson

With equal cell densities, surface film thickness did not influence the numbers &Salmonella typhimurium and Listeria monocytogenes cells which attached to glass. Motile L. monocytogenes cells had a greater cell surface charge and generally attached in higher numbers than non-motile cells.

Control Of Salmonella Typhimurium, Listeria Monocytogenes, And Escherichia Coli 0157:H7 On Beef In A Model Spray Chilling System, James S. Dickson

James S. Dickson

Simulated water spray chilling cycles were modified to include acetic acid as a sanitizer. The modified cycles were tested for effectiveness in reducing levels of S. typhimutium, L. monocyfogenes, and E. coli 0157:H7 on beef lean and fat tissue. Reductions of up to 3 log cycles were obtained for all three bacterial species on fat tissue. Reduction was less on lean tissue with the same treatments, although the modified cycles reduced populations when compared to the control cycle.

Storage And Bacterial Contamination Effects On Myofibrillar Proteins And Shear Force Of Beef, James S. Dickson, John D. Crouse, M. Koohmaraie

James S. Dickson

Thirty-two steaks from the longissimus muscle, fifth rib to third lumbar vertebra, were obtained from youthful carcass beef. Half were sterilized by ultraviolet light and all vacuum packaged and stored for 1, 14, 28 or 57 days at 2°C. After storage, steaks were examined for microbial populations, myofibril fragmentation index (MFI), cooking characteristics and shear force (SF). Aerobic and anaerobic counts decreased during storage. Psychrotrophic counts were low throughout. Sterilization had no effect on SF or MFI. Cooking loss tended (P < 0.09) to increase with time of storage. SF values decreased and MFI values increased through day 14, but remained relatively constant after that. Results of SDS-PAGE, SF and MFI indicate major changes in proteolysis of myofibrils and tenderness were completed by day 14.

Attachment Of Salmonella Typhimurium And Listeria Monocytogenes To Beef Tissue: Effects Of Inoculum Level, Growth Temperature And Bacterial Culture Age, James S. Dickson

James S. Dickson

The effects of inoculum level, growth temperature and culture age on the attachment of Salmonella typhimurium and Listeria monocytogenes to beef tissue surfaces were evaluated. An increase in inoculum level resulted in an increase in the number of attached cells for both bacteria which was proportional to the increase in inoculum. Bacteria grown at 23°C attached in higher numbers flVO5) to fat tissue than bacteria grown at 37°C or at 37°C followed by 24 h at 5°C. Growth temperature did not affect attachment to lean tissue for either bacterium. Overnight cultures of both bacteria attached in greater numbers 0VO.05) to …

Surface Moisture And Osmotic Stress As Factors That Affect The Sanitizing Of Beef Tissue Surfaces, James S. Dickson

James S. Dickson

The use of osmotic stress or desiccation in combination with 2% acetic acid reduced the numbers of Salmonella typhimurium or Listeria monocytogenes on beef tissue to a greater degree than the acid alone. Bacteria were osmotically stressed by NaCl, CaCl2, or sucrose solutions. Pre-washing with 20% NaCl followed by sanitizing with acetic acid reduced the numbers of S. typhimurium an additional 1.5-to 2-log cycles compared with acetic acid alone. Similar reductions were seen by allowing the tissue surfaces to dry before the application of the acid. Desiccation in combination with acetic acid was also effective in reducing the numbers of …

Transfer Of Listeria Monocytogenes And Salmonella Typhimurium Between Beef Tissue Surfaces, James S. Dickson

James S. Dickson

Beef tissue surfaces were inoculated with either Listeria monocytogenes or Salmonella typhimurium and placed in contact with uninoculated tissue surfaces. The transfer of bacteria from one surface to another was determined under conditions designed to simulate contamination during meat processing. Bacterial transfer decreased when the initial inoculum was allowed to adsorb to the base tissue prior to contact with the second tissue. The type of base tissue was a factor (P<0.05), with a greater transfer from fat with contact times of less than 1 min and a greater transfer from lean with longer contact times.

Comparison Of Homogenization By Blending Or Stomaching On The Recovery Of Listeria Monocytogenes From Beef Tissues, James S. Dickson

James S. Dickson

Homogenization by blending or stomaching was compared for the recovery of Listeria monocytogenes from inoculated intact beef tissue. There were no differences in numbers of recovered bacteria (P > 0.10) attributable to either homogenization time or method. Fewer viable bacteria (PcO.05) were recovered in phosphate buffer than either buffered peptone water or 2% trisodium citrate buffer. Tween 80 increased the numbers of bacteria recovered from fat tissue (PcO.05). Stomaching is an acceptable method for homogenizing samples for Listeria analysis.

Attachment And Proliferation Of Bacteria On Meat, James S. Dickson, King-Thom Chung, John D. Crouse

James S. Dickson

The attachment of bacteria (Serratia marcescens, Staphylococcus aureus, Streptococcus faecalis, Salmonella arizonae, Pseudomonas aeruginosa, and Listeria monocytogenes), to lean muscle tissue and fat tissue was investigated. The number of cells attached to the meat was directly proportional to the initial cell concentrations present. There was no significant difference in the number of cells attached between the lean muscle tissue and fat tissues among the organisms tested. All bacteria tested except P. aeruginosa proliferated better on the lean muscle tissues than on the fat tissue at ambient temperature for 72 h. No significant attachment competition to tissue samples was seen between …

Effect Of Electrical Charge On Attachment Of Salmonella Typhimurium To Meat Surfaces, James S. Dickson, John D. Crouse

James S. Dickson

Treating tissue with electrical current was found to affect both the initial attachment and total numbers of attached Salmonella typhimun’unl to meat tissues. When lean tissue was attached to the positive terminal of the power supply operating at 50 volts/125 mA DC, the total numbero f attachedc ells increasedT. hcrc was no effect when the samples were attached to the negative terminal. There was a significant (PcO.05) effect on the percentage of strongly attached bacteria with an increase in treating time. Electrical current was found to increase the percentage of strongly attached cells immediately after the current was applied.

Effects Of Dietary Fiber And Protein Concentration On Growth, Feed Efficiency, Visceral Organ Weights And Large Intestine Microbial Populations Of Swine, James S. Dickson, Friday O. I. Anugwa, Vincent H. Varel, Wilson G. Pond, Lennart P. Krook

James S. Dickson

Finishing barrows (average initial weight 55.5 ±2.4 kg) were used to determine the effects of high dietary fiber or protein on performance, visceral organ weights and large intestine microbial populations and to monitor the duration of regression of swine visceral organ mass and microbial populations to control values following trans fer from the high fiber or high protein diet to the control diet Four pigs from each diet were killed on d 17, 34, 48 and 66. From d 34 until slaughter 14 and 32 d later, all remaining pigs were fed the control diet ad libitum. High fiber resulted …

Lupinosis, M R. Gardiner

Journal of the Department of Agriculture, Western Australia, Series 4

In spite of many years of intensive investigation lupinosis remains a remarkably complex and baffling problem. Current research is throwing new light on the disease and it is now much better understood— although far from beaten.

Lupinosis research is co-ordinated by the Department of Agriculture's Lupinosis Committee, on which are represented all groups working on the disease. These include veterinary surgeons and pathologists, chemists, plant pathologists and animal husbandry specialists.

Chairman of the Committee is Dr M. R. Gardiner, Chief of the Department's Animal Division and a veteran of lupinosis research.

In this article Dr Gardiner summarises the current state …