Food Safety, Great Plains Institute of

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Research from the Great Plains Institute of Food Safety. The institute website may be found at https://www.ag.ndsu.edu/foodsafety

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Antimicrobial Resistance and Presence of Integrons in Salmonella Isolated from Animals and Humans in the United States of America and Uganda
(North Dakota State University, 2010) Mahero, Michael Wandanje
Salmonella has been cited as one of the leading causes of food borne illness world wide and in the United States (US), as well as an indicator organism for studying antimicrobial resistance (AMR) trends. The objective of this study was to characterise AMR patterns of Salmonella isolates from animals and humans in North Dakota, US, and Kampala, Uganda, and determine the association between the observed AMR and presence of class 1 integrons. Salmonella isolates were collected from the Veterinary Diagnostic Laboratory (VDL) at North Dakota State University and the North Dakota Department of Health respectively from 2003-2008. Samples were also retrieved from archives present at the Microbiology Department, Faculty of Veterinary Medicine at Makerere University in Kampala, Uganda. AMR profiles were determined using a panel of 15 antimicrobials as per the manufacturer's instructions (Sensitire, Trek Diagnostics System, Westlake, Ohio). Screening for the class 1 integrons was done using PCR with primers specific for the int 1. Out of 359 Salmonella isolates tested, 24. 79% were resistant to ~5 antimicrobials while 36.2% were resistant to at least 2. Pan susceptible isolates were mostly (65.05%) from human isolates. The most common multidrug resistant (MDR) phenotype among the tested isolates was the classic ACSSuT penta-resistance at 29.06% (50/172). The highest resistance frequency was seen against Tetracycline (39.6%) and Streptomycin (34.7 %), while 5.2% (17) of the isolates were resistant to Nalidixic acid and 56 (15.7%) to Ceftiofur. A total of20.7% (57/276) of the ND samples tested positive for presence of class 1 integrons. Class 1 integron was significantly associated (p< 0.05) with AMR to Ampicillin, Kanamycin, Tetracycline, Streptomycin and Sulfisoxazole. Of all Ugai.dan Salmonella isolates tested, 94.4% (68/72) were resistant to 2':2 antimicrobials. The highest resistance was observed against Sulfisoxazole and Trimethoprim-Sulphamethoxazole, and 45.8% of human and 46.2% of cattle isolates tested positive for presence of class 1 integrons. Presence of class 1 integron was significantly associated (p< 0.05) with AMR to Tetracycline and Amoxicillin. DNA sequencing of the class 1 integron variable regions identified several resistance genes including aadAJ, dfrA 7, and dfrA5 gene. The data indicated high AMR among antimicrobials widely used in veterinary and human medicine. Also, AMR was observed against drugs whose veterinary use is restricted, implying possible horizontal transmission. A good proportion (47.9% in Uganda and 29.85% in ND) of the Salmonella isolates from clinical cases of salmonellosis were MDR (resistant to 2':2) isolates bearing class 1 integron.
Relatedness ofisolates of a Novel Genus, Cronobacter, Formerly Known as Enterobacter sakazakii
(North Dakota State University, 2010) Solseng, Tracy Anne
Members of the genus Cronobacter were once classified as Enterobacter sakazakii. These bacteria are opportunistic pathogens that are associated with necrotizing enteritis, sepsis and meningitis in neonatal or low-birth-weight infants and can result in death, slowed development, or extensive neurological disorders. In adults, they have been documented as a cause of bacteremia, osteomyelitis, and vaginitis. Previously, E. sakazakii was found in the midgut of stable flies. Research by Nangoh et al. determined that Cronobacter spp. (previously identified as E. sakazakii) are present in bison and bovine feces. In addition to the bison and bovine fecal isolates of Cronobacter spp. found by Nangoh et al., other isolates of Cronobacter spp. were analyzed phenotypically and genetically for biochemical typing and genotyping. The additional isolates include several American Type Culture Collection isolates, an isolate from a neonatal meningitis case, and multiple isolates of various origins received from Cornell University. These isolates were further categorized using four different biochemical tests. The results of these tests placed the isolates into one of the six different species or subspecies within the genus Cronobacter. For genotyping, the isolates were tested for the gene specifically responsible for the a-glucosidase activity. In addition, Pulsed-Field Gel Electrophoresis using two different enzymes, Xbal and Spel, was performed to determine possible genetic similarity of isolates from the bison and bovine feces to other isolates found in food, clinical and environmental settings. The X'baI enzyme showed two Cornell isolates, F6-049 and F6-051, had a high degree of similarity; both of these isolates were from the same clinical source. Isolates from bison and bovine feces, 52 and N72, respectively, have a high degree of dissimilarity to each other, ~ 75%. Isolate 52 showed ~ 35% dissimilarity to an isolate from a food source, and N72 showed ~45% dissimilarity to an isolate from a clinical source. The results using the Spel enzyme showed a wide diversity among the isolates. This study shows that very few of the Cronobacter spp. isolates are closely related and that there is a high level of diversity based on pulse-field gel electrophoresis and biochemical analysis.
Development of Real-Time PCR Method for Detection, Identification and Quantification of Five Different Fusarium Species
(North Dakota State University, 2010) Goswami, Kakolie
Fusarium head blight (FHB) is a fungal disease affecting cereal crops worldwide. FHB involves multiple Fusarium species that create food safety concerns by producing mycotoxins such as trichothecenes, zearalenone and moniliformin. Quantitative methods allowing rapid risk assessment of mycotoxigenic Fusarium species are needed to detect Fusarium spp. Real time quantitative PCR (qPCR) is a fast, sensitive and reliable alternative to conventional culture methods. An objective of the study was to develop TaqMan® based qPCR methods to detect, identify and quantify five different Fusarium species associated with FHB, namely F. graminearum, F culmorum, F avenceum, F poae and F sporotrichioides. The project was initiated with the selection of a protocol for Fusarium DNA extraction. Three different commercially available DNA extraction kits, including FastDNA ®, Qiagen® Blood & Tissue kit and Qiagen® DNeasy Plant kit were evaluated for speed, DNA yield and quality. The results showed that FastDNA ® kit gave the highest DNA yield in least time. TaqMan® Minor Groove Binder (MGB) probes for F culmorum, F poae and F sporotrichioides were developed using qPCR primers from a previous study. For F avenaceum and F. graminearum, TaqMan® based methods already available were used with modified conditions for improved detection. The qPCR methods were tested on a wheat system and the result was a qPCR system that rapidly identified and quantified Fusarium species associated with FHB.
Proteomic and Molecular Analysis of Methicillin Resistance and Selected Toxigenic genes in Coagulase-negative Staphylococcus spp From Food and Animal Sources.
(North Dakota State University, 2010) Aye, Racheal
While most coagulase-negative Staphylococcus (CNS) are apathogenic, recent evidence suggests some food and animal derived CNS isolates may carry and express virulence factors including classical enterotoxins, toxic shock syndrome, and methicillin resistance genes. The present study was designed to assess the potential role of CNS in the epidemiology of foodborne illnesses and to determine the likelihood of food and domestic animals as transmission vehicles of methicillin resistance. Of the animal-derived food samples tested, 27.3% (39/143) were Staphylococcus-positive compared to only 9.5% (23/242) of the plant foods. A total of 92 Staphylococcus spp cultured from 385 food (62/92) and 30 diagnostic animal (30/92) samples were tested by the polymerase chain reaction (PCR) for classical enterotoxin (sea, seb, sec, sec/, and see), toxic shock syndrome toxin-1 (tsst-1), and mecA genes. All PCR-positive isolates were further tested by immunoblotting for production of the corresponding toxin. Susceptibility patterns of both CNS and coagulase-positive Staphylococcus (CPS) were assessed for ~- lactam antimicrobial agents and the isolates analyzed for presence of the mecA gene. Of all study isolates, 20/92 (21.7%) were CPS and 72/92 (78.3%) CNS. Of the 20 CPS isolates, 15.4% (2/13) 5. aureus cultured from steak were sec positive while only 1/7 (14.3%) CPS (5. aureus) from a diagnostic feline sample was positive for both sec and tsst-1 genes. Both toxigenic 5. aureus isolates from steak and a diagnostic feline sample also expressed detectable amounts of SEC and TSST-1 toxins. On the other hand, 1.4% (1/49) of the CNS (5. lugdunensis) from strawberries was positive for the sec gene but negative for SEC toxin and 2/49 (2.8%) of the CNS (5. hominis) gave unexpected base pair PCR products with see primers. All CNS isolates were generally susceptible to test ~-lactam antimicrobial agents; 80% of the CPS isolates were resistant to penicillin and amoxicillin of which 1/20 (5%) were positive for the mecA gene. Based on this data, 3/20 (15%) of CPS and 3/72 (4.2%) of CNS isolates were positive for toxigenic genes thus underscoring the potential role food-derived CNS isolates may have in the epidemiology of foodborne illnesses. Although only 5% of the CPS and none of the study CNS isolates expressed mecA gene, 80% of the CPS were resistant to penicillin, suggesting other mechanisms of drug resistance. The presence of mecApositive CPS and toxin producing Staphylococcus isolates underscore the public health significance of organisms from this genus.
An In-vitro Co-Culture Model to Study the Disruption of the Blood Brain Barrier by Cronobacter sakazakii. (formerly Enterobacter sakazakii)
(North Dakota State University, 2010) Koval, Erin Louise
Cronobacter spp. (formerly Enterobacter sakazakii) is an opportunistic pathogen associated with contaminated powdered infant formula. It causes necrotizing enterocolitis (NEC) and sepsis, which can develop into severe meningitis and brain abscess formation in infants. Very little is known about the specific pathogenic mechanisms of this organism. In this study, we propose a model to investigate the ability of Cronobacter spp. isolates to disrupt the blood-brain barrier. Biofilm formation of the Cronobacter spp. isolates used in the model was also assayed. Secondary mouse endothelial and astrocyte cells were grown to con.fluency on polyethylene terephtalate (PET) membranes (1.0 μm pore size) in 24-well plate hanging culture inserts (Millipore® Billerica, MA) to achieve a culture system similar to the physiological structure of the blood brain barrier in vivo. Initially, a monoculture system was tested containing only endothelial cells and then a co-culture system was developed with both cell types. Selected Cronobacter spp. isolates were added to the cell culture systems. Escherichia coli KI and Kl2 strains were used as positive and negative controls, respectively. Some of the treatments did not have bacteria added to them to serve as cell controls, and membranes without cells were included as media control blanks. The transendothelial electrical resistance (TEER) was measured across the cells to determine if the cell barrier was disrupted. Initially, measurements were taken at 0, 6, 24, and 48 hours after adding bacteria. Due to overall loss of cell integrity at 48 hours, a second experiment was performed where measurements were taken at 0, 6, and 24 hours after adding the bacteria. Biofilm formation was analyzed using a method described by O'Toole (72) and Skyberg (86). The monoculture and co-culture systems worked based on TEER measurements. The positive control (E.coli Kl) and Cronobacter sakazakii isolates disrupted the tight junctions between cells evidenced by significant decrease in TEER over time. The negative control (E.coli K12) did not have any significant effect on the cells. The cell control and negative control (E.coli Kl2) maintained the highest resistance values in both the monoculture and co-culture experiments. The positive control (E. coli Kl) and the Cronobacter sakazakii isolates caused the resistance across the cells to significantly decrease over time in both experiments. According to the results of our biofilm assay, none of Cronobacter spp. isolates used in the culture models formed biofilms. Further testing would need to be done using other biofilm detection procedures to confirm this conclusion Overall, we successfully constructed a co-culture model to depict the BBB. The selected Cronobacter sakazakii decreased resistance in this model of the BBB similar to the positive control Kl E.coli isolate. This assay can be used in future studies to test the potential pathogenicity of Cronobacter spp. bacteria as well as other bacteria involved with central nervous system diseases.
A Quantitative Cost Model of HACCP Implementation
(North Dakota State University, 2011) Wu, Zhen
Foodbome illness is an important public health problem in the United States. Hazard Analysis Critical Control Point (HACCP) is widely acknowledged as an effective method to ensure product quality and control foodbome hazards. Existing literature considers the economic aspects of implementing a HACCP plan and identifies the major cost items for specific firms but stops short of providing a model to quantitatively analyze the cost of HACCP implementation over a variety of firms. This research used the case study method to refine the Prevention-Appraisal-Failure (PAF) model to identify potential costs associated with the implementation of HACCP plans and develop a cost estimation model for calculating total cost. The model was refined based on the process of applying it to two North Dakota food processing plants.
Occurrence of Salmonella and Listeria Monocytogenes in Ready to Eat Meats in the United States: 2000-2010
(North Dakota State University, 2012) Ntaate, Anthony Wilfred
The purpose of this review is to characterize the occurrence of Salmonella and Listeria monocytogenes in ready to eat (RTE) meats in the United States between the years 2000-2010. Data were obtained from the CDC foodborne outbreak online database, morbidity and mortality weekly reports, summary of notifiable diseases and the foodborne outbreaks page. Additional information was obtained from peer reviewed journals. RTE roast pork, turkey deli meat, and Italian type salami meats were the vehicles in the Salmonella outbreaks reported. Half of the eight outbreaks reviewed were multistate in nature affecting many states and the rest were sporadic. The Salmonella serotypes isolated were Salmonella Uganda, Salmonella Hadar, Salmonella Montevideo, whereas the L. monocytogenes serotypes were 1/2a and 4b. The major risk factors for listeriosis and salmonellosis outbreaks were being elderly and having an underlying immunocompromising medical condition. Pregnant women were particularly at risk for listeriosis.
Does Consumption of Beef from Cattle Administered Growth-Enhancing Technology Trigger Early Estrus in Pre-Pubertal Gilts?
(North Dakota State University, 2012) Anderson, Giovana Maranho
The objective was to determine if pre-pubertal gilts supplemented ground beef obtained from steers implanted with growth enhancing technology caused precocious puberty. Twenty-four gilts were selected for the same birth date from common parentage. Upon reaching 61 days of age, daily delivery of the low-estrogenicity base diet was supplemented with: 114 g beef natural patty (NAT), 114 g beef patty from steers that had received growth promoting implants (100 mg trenbolone acetate and 14 mg estradiol benzoate; IMP), 198 g tofu patty (TOFU), or the negative control (base diet only; CON). The estradiol equivalents (ng/kg) of the TOFU were approximately 500 fold times the NAT and 350 fold the IMP supplement. No differences (P = 0.55) were observed in number of days to reach estrus, feed efficiency (P > 0.19), live weight gain (P = 0.89), loin muscle development (P = 0.45), or subcutaneous fat deposition (P = 0.71).
Analysis of Deoxynivalenol and Deoxynivalenol-3-glucoside in Wheat
(North Dakota State University, 2012) Burgess, Kimberly
Deoxynivalenol (DON), a mycotoxin produced in cereal grains infected by Fusarium Head Blight produced by Fusarium graminearium and Deoxynivalenol-3-β-D-glucopyranoside (DON-3G), were studied during processing using LC-MS-MS and GC. DON reduced significantly (P<0.05) 61.8% during milling into flour. Therefore, DON was concentrated mostly in the bran and germ. DON increased 40.8% during the fermentation stage of baking. DON increased in dough more than flour and mixed dough. Milling reduced by 23.7% but fermentation did not. But bread was significantly lower in DON-3G at 0.15 ppm than flour and dough at 0.31 ppm. The baking increased DON and decreased DON-3G showing a difference in stability of the mycotoxins during processing. Enzyme hydrolysis on DON using α-amylase, cellulase, protease, and xylanase, showed a significant increase with cellulase (20.8%), protease (11.4%), and xylanase (35.6%) compared to wheat composite. DON may be bound to the cell wall or protein component of the kernel.
Assessing Microbial Stability and Quality of Green Beans Using Various Home Canning Methods
(North Dakota State University, 2013) Kuchynski, Jenny
Today many consumers follow processing methods recommended either from family members or the internet, which they interpret as being safe. Processing temperature profiles, survival of B. stearothermophilus spores, texture, and color of green beans processed under four home canning methods were assessed. The products were processed using pressure, boiling water bath, steam, or oven canning methods. Pressure canning produced the greatest microbial reductions but this method resulted in the lowest bean quality. The boiling water bath, steam, and oven canning were found to be less safe because the product temperature never achieved 100°C and the resulting microbial counts, >1.7 log CFU/ml, were observed after processing. However, green bean quality was better than pressure canning, with beans from steam canning having the firmest texture and best green color. Although better green bean quality results were observed from internet or family based methods, their safety is questionable considering the high microbial survival.
Synthesis and Antioxidant, Anticancer, and Antimicrobial Activities of Palmityl Ester Derivative of Carnosic Acid
(North Dakota State University, 2013) Prasad, Asharani
Carnosic acid (CA) along with carnosol (CAR) is the strongest phenolic diterpene antioxidants (PDAs) present in rosemary plant. However, CA has low antioxidant activity in emulsion-type food system due to its polar nature. The identification and characterization of the anticancer and antimicrobial properties of natural products and their semisynthetic derivative such as that of CA and CAR have received significant interest over the years. The goals of this research were to synthesize lipophilic palmityl derivative (PE) of CA and study its antioxidant activity in bulk and emulsified corn oil. Anticancer properties against CCRF-CEM, K-562 and P388D1 leukemia cell lines and antimicrobial activity against Staphylococcus auerus (S. auerus), Bacillus cereus (B. cereus), Salmonella enterica, and Escherichia coli (E. coli) O157:H7 bacteria were also tested. A four steps synthetic route was designed. In the first step CAR was converted into a benzyloxy protected benzyl ester of CA (yield 78%). Reduction of the benzyl ester to a primary alcohol (yield 63%) followed by esterification with palmitoyl chloride gave the palmityl ester derivative (yield 97%). Finally, double bond reduction followed by deprotection of benzyloxy group gave PE (yield 99%). Overall yield for the route was 47%. The modification of CA affected functionality. PE had improved antioxidant activity in emulsified corn oil compared to bulk corn oil than the CA. However, CA was more effective in bulk oil. Compounds with hydroxyl groups were found to have cytotoxicity against three cell lines CCRF-CEM, P388D1 and K-562. Among compounds tested, CAR was found to be the most potent anticancer agent against all three cell lines. The study also indicated structure dependent activities for the compounds that had hydroxy group at the C-20 position. CA and CAR had antimicrobial activity against S. auerus, B. cereus, Salmonella, and E. coli O157:H7. S. auerus, B. cereus were more sensitive to CA and CAR than Salmonella, and E. coli O157:H7. Other compounds, without hydroxyl groups, did not have antimicrobial activity. Study also indicated that antimicrobial activity varied depending on functional group present at C-20 position. Compound PE did improve antioxidant activity in emulsion but did not improve antimicrobial activity.
The Occurrence of Shiga-Toxin Producing Escherichia Coli (Stec) and Salmonella Species in Cattle Feedlot Runoff
(North Dakota State University, 2013) Tabe, Nessie Nanyongo
Zoonotic foodborne pathogens such as shiga-toxin producing Escherichia coli (STEC) and Salmonella on farm environments can potentially contaminate organic manure or agricultural watersheds and subsequently fresh produce during fertilization or irrigation. This study investigated the occurrence of STEC and Salmonella serotypes in cattle feedlot runoff samples in two feedlots in North Dakota. Using standard laboratory culture methods this study reported a 39% prevalence of STEC O45, 33 % (O103), 31 % (O157), 27 % (O121), 16 % (O26), 10% (O111), 10% (O113), 10 % (O145) and 39.7 % Salmonella. Additionally, occurrence of some STEC serotypes was influenced by feedlot (O111 and O121), sampling location in relation to vegetative filter strips (O157), and sampling time (O45 and O121). Although this study was the first to report occurrence of STEC serotypes including non-O157 serotypes in cattle feedlot runoff, further studies are needed to quantify the pathogen load in runoff prior to disposal.
The Use of Communication Strategies to Influence Stakeholders to Implement Food Safety Management Systems in Small Custom-Exempt Meal Plants
(North Dakota State University, 2014) Rathnasinghe, Shalindra Suresh
This exploratory study used interviews to understand the culture and communication patterns of the stakeholders, employers, and employees. Interviews revealed that the topic of Food Safety was a very sensitive one as many were reluctant to share information. The study found that direct informal communication strategies are the best method to communicate custom-exempt meat plants. These communication strategies can be used to influence food safety practices.
Ochratoxin A and Ochratoxigenic Fungi in Freshly Harvested and Stored Barley and Wheat
(North Dakota State University, 2014) Kuruc, Julie
Ochratoxin A (OTA) is a toxin produced both prior to harvest and during storage by Penicillium and Aspergillus species in a variety of commodities. Although several studies have been conducted in Europe and Canada examining the occurrence and concentration of OTA in cereal grains, data is lacking for the United States, where guidance levels and regulations do not exist. This study aims to fill in the knowledge gaps surrounding OTA and ochratoxigenic fungi in barley and durum and hard red spring wheat grown in the northwestern and Upper Great Plains regions of the United States. In total 2.7% (n = 37) of the 1370 samples taken over 2 consecutive years had detectable levels of OTA (0.15-9.11 ng/g) directly after harvest. The number of positive samples was significantly greater in 2012 compared to 2011. This difference may be due to weather conditions during the planting and growing seasons or simply natural variation between years. Stored barley and wheat (N = 262) had a higher prevalence (12.2%) and greater range (0.16-185.24 ng/g) of OTA compard to freshly harvested samples. Although 81.3% of the OTA-positive samples had been stored for ≥6 months, samples that had been stored for as short as 1 month also tested positive. These results underline the importance of proper storage conditions in minimizing OTA contamination. P. verrucosum was found to be the primary ochratoxigenic species in these samples. Of the 110 isolates tested, 64.7% were confirmed OTA producers. Samples containing >1 ng/g OTA had significantly more OTA-producing P. verrucosum strains than samples with undetectable OTA. Infestation rate did not correlate with OTA level. Additionally, OTA concentration did not correlate with otanpsPN, an OTA biosynthesis gene. This indicates that the concentration of P. verrucosum in a sample may increase the likelihood of contamination but is not a reliable indicator of OTA level.
Escherichia Coli in Bovine Calf Scours
(North Dakota State University, 2015) Starr, Crystal
Scours is caused by inflammation of the intestinal tract of ruminants leading to significant mortality and morbidity rates. It is predominately found in neonatal ruminants where the disease can occur 36 hours after birth. One of the most common infectious agents linked to scours is pathogenic Escherichia coli. Therefore, it is important to understand the virulence factors, diagnostic assays, age of the animals infected, and the co-factors associated with an E. coli scours outbreak. These factors are important in both scours disease pathogenesis and potential food safety-related postharvest pathogens. Using the most frequently identified virulence factors, a new scours diagnostic assay could be created to detect and prevent disease in cattle. The present study determined that virulence factors astA, fimC, fimH, int1, int2, irp2, papC were identified over 15% percent of the time and could be implemented into a more specific multiplex PCR test for pathogenic E. coli.
Fate of Deoxynivalenol and Deoxynivalenol-3-Glucoside during the Malting Process
(North Dakota State University, 2015) Jiang, Wei
Deoxynivalenol (DON) is commonly found on small grains and causes food safety issues. Deoxynivalenol-3-Glucoside (DON-3-G) is a conjugate, formed as a defense response by the host plant. Past studies have shown both to be present in Fusarium infected small grains, and processed products like beer, but there is limited information on DON-3-G in malt. Objectives were to determine the levels of DON-3-G in barley and wheat, and to study its fate during malting of inoculated and commercial samples. Commercial barley and wheat samples were used to determine levels in naturally infected grain. During malting, barley DON declined 48% on average, but DON-3-G increased by 115%. Both compounds increased in malted wheat. The genotype x crop year interactions were significant for both toxins, indicating that the genotypes did not respond similarly in the two years. The potential for large amounts of DON-3-G to be formed during malting has not been reported.
Total Glucosinolate Preservation and Near Infrared Prediction in Rapeseed Meal
(North Dakota State University, 2015) Kittelson, Jayd Marshal
Glucosinolates (GLS) and their hydrolysis products are of great food and feed safety concern because they are responsible for both the beneficial and harmful properties of GLS-containing plants. Understanding GLS storage stability and total GLS concentration in Brassica oil meals is important to ensuring livestock health. The storage stability of GLS and potential of near infrared spectroscopy (NIRS) for screening the total GLS content of various Brassica meals obtained globally and over multiple growing seasons was evaluated. Decreases were observed in meal stored at 4 oC. GLS storage stability within stored Brassica meals was possible for 18 months and possibly longer providing the seed meals are protected from exposure to moisture conditions that promote endogenous myrosinase hydrolysis. NIRS spectra data from 400 to 2500 nm were recorded on various Brassica meal samples (186) at 2 nm intervals. A global calibration using the Brassica database was developed for both ground and unground meal samples with a modified partial least squares regression analysis of conventional laboratory analysis. The optimum NIR calibrations utilized the first derivative and standard normal variate data preprocessing. The ground NIRS calibration for total GLS resulted in a coefficient of determination (R2) and standard error of the calibration (SEC) and relative predictive determinant (RPD) of 0.96, 6.05, and 6.32, respectively, while the unground NIR calibration had a R2, SEC, and RPD of 0.93, 7.65, and 5.88, respectively. Finally, a sample set (20) with known GLS concentration (by HPLC) was split and one subset was analyzed via NIR “as is” and the other subset was analyzed by NIR after drying for 16 hours at 60 oC in a vacuum oven. The dried Brassica meal sample set had a slightly better residual (HPLC - NIR) standard deviation (4.57) and average residual (-0.74), compared to the “as is” moisture sample set standard deviation (5.00) and average residual (-1.26). The use of NIRS as a routine analytical method for total GLS in Brassica meals destined for animal feeds has great potential. In addition, the low cost of the NIR analysis may be attractive for manufacturers of Brassica meals.
Detection and Molecular Typing of Methicillin-Susceptible Staphylococcus Aureus (MSSA) and Methicillin-Resistant Staphylococcus Aureus (MRSA)
(North Dakota State University, 2015) Velasco, Valeria
Methicillin-resistant (MRSA) and multidrug-resistant (MDR) Staphylococcus aureus, and the serotype (ST) 398 have been associated with human and livestock infections, being also detected in retail meat. The aim of this study was to determine the prevalence and molecular types of S. aureus strains from animals, retail raw meat, deli meat, and humans, determining the genetic similarity between the strains. A two-step selective enrichment followed by selective plating were used to isolate S. aureus from animals (n=167), retail raw meat (n=145), and deli meat (n=46). In addition, S. aureus from healthy people (n=550) was isolated by culture method. Positive isolates and MRSA isolates from clinical cases (n=108) were subjected to multiplex PCR (16S rRNA, mecA, and PVL genes), molecular typing and antimicrobial susceptibility testing. In addition, a real-time PCR assay was developed in order to decrease the time of detection of target genes of S. aureus in animal and meat samples, comparing the results with the standard culture/PCR method. The prevalence of S. aureus was 34.7% in animals, 47.6% in meat, and 13.0% in deli meat. The mecA gene was detected in S. aureus isolated from five pork meat samples and exhibited penicillin resistance. The ST398 was found in sheep, pigs, and pork meat. The S. aureus nasal carriage in healthy people was 7.6%. A total of 105 MRSA strains (97.2%) from clinical cases harbored the mecA gene and 11 (10.2%) the PVL gene. The rate of MDR was 70% in humans. A genetic similarity between strains from animals and meat, and from humans and meat was observed. Total agreement between the culture/PCR method and real-time PCR for detection of S. aureus was 68.9 to 97.8% (k=0.68-0.88), and the mecA gene, 86.7 to 98.7% (k=0-0.49). Therefore, the real-time PCR assay may be recommended as a rapid method for the detection of S. aureus, with confirmation of MRSA using the standard culture method. The presence of emerging S. aureus strains in the meat production chain and the genetic similarity between strains of different origin, suggests the contamination of meat, and a potential risk of transmission to humans.
Wheat Dockage Content: Analysis of Dockage and Its Relation to Fusarium Head Blight
(North Dakota State University, 2016) Alhumaid, Taghrid Saleh
Hard red spring wheat crop grown in different locations in the US were surveyed for the mycotoxin deoxynivalenol (DON). DON is often found in wheat that is infected with the plant fungal disease Fusarium head blight. The contamination of wheat by DON is a major wheat industry concern since it affects human and livestock health. Furthermore, DON reduces wheat grain yield and quality. In this study, DON was measured using gas chromatography with electron capture detection (GC-ECD) in 1353 HRS wheat samples collected from 2013-2015. Results indicate that there was positive significant correlation (P<0.001) between DON content and damaged kernels (0.635) and total defects (0.445). However, for the three-year average, DON content had a weak positive significant correlation (P<0.001) with the percentage of wheat dockage (0.111). Overall, DON production had an effect on kernel damage and total defects, but DON production was not impacted by the percentage of wheat dockage.
Listeria Monocytogenes in the Retail Food Service Environment
(North Dakota State University, 2018) Walpuck, David Andrew
Listeria monocytogenes is one of the biggest microbial concerns affecting today’s food industry. It is a ubiquitous liability with a high mortality rate, unique characteristics of growth and survival in many environmental conditions, making the pathogen a true risk to consumer health. Recent outbreaks of listeriosis have caused fatalities, massive well-publicized recalls costing the food industry heavy financial losses and damaged reputation. L. monocytogenes is the forefront of impediment and educational efforts from private industry and government agencies. The purpose of this study is to assess the features and concern of L. monocytogenes in the retail food service environment and its impact on operations. Regulatory surveillance of testing environmental samples and food products for L. monocytogenes highlight prevention. Organizations in the retail food service industry need a separate plan for training, food handling, sanitation and financial allocation to combat the potential threat of L. monocytogenes contamination.

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