Application of Models for Safeguarding the Milk Supply Chain

The objective of this thesis was to develop a simulation model in order to identify actors and flows of goods, which can promote the spread of a hypothetical contamination in the dairy industry. Based on the model results, strategies to safeguard the milk supply chain were derived for decision-makers. The first step for creating a simulation model was to develop a conceptual model, in which the actors and the structural trade links between the actors are described. For quantifying these trade links a substantial amount of data about the real flow of goods in the dairy industry could be used. Based on the conceptual model, an economic model for predicting trade relations was newly combined with optimization algorithms. On the one hand, for simulating the spatial distribution of a hypothetical contamination, taking into account various flows of goods between the actors. The simulated damage situation was quantified in terms of the distinctive model parameters virulence, resistance and vulnerability of actors as well as the geographical range of a contamination. In particular, it was necessary to assess the impact of trade between the dairies on the spatial spread of a contamination. The basis for the carried out modeling formed 500 trade networks that represent 61.43% of the existing flows of goods of processed milk in Germany. These networks comprise varying trade relations between 294 milk producers, 80 dairies and 12,223 consumers. On the other hand, a management plan for decision-makers was designed, where surveillance measures for minimizing the size of damage were derived from. The model results indicate that actors and structures exist that promote the spread of a hypothetical contamination in the dairy industry. First, the risk for the consumer to be supplied with hypothetical contaminated milk is up to three times higher on average, if a trade between dairies exists, compared to the neglect of the trade. In this context, also the spread of contaminated milk through the milk producers can be up to four times higher on average. Second, under consideration of the predetermined scenario, the management plan shows that control measures should be introduced on 40% of the milk producers in order to minimize the damage.Anwendung von Modellen zur Sicherung der Milchversorgungskette Ziel der vorliegenden Arbeit war es, ein Simulationsmodell zu entwickeln, um ausbreitungsfördernde Akteure und Warenströme für den Fall einer hypothetischen Kontamination in der Milchwirtschaft zu identifizieren. Basierend auf den Modellergebnissen wurden Strategien zur Sicherung der Milchversorgungskette für Entscheidungsträger abgeleitet. Der erste Schritt für die Erstellung eines Simulationsmodells war die Entwicklung eines konzeptionellen Modells, in dem die Akteure und die handelsstrukturellen Verknüpfungen zwischen den Akteuren beschrieben werden. Bei der Quantifizierung dieser Handelsbeziehungen konnte auf umfangreiche Datensätze über die realen Warenströme in der Milchwirtschaft zurückgegriffen werden. Aufbauend auf dem konzeptionellen Modell wurde im zweiten Schritt ein Modell aus der Wirtschaftswissenschaft zur Vorhersage von Handelsbeziehungen mit Optimierungsalgorithmen neu kombiniert, um einerseits die räumliche Ausbreitung einer hypothetischen Kontamination, unter Berücksichtigung divergierender Warenströme zwischen den Akteuren, zu simulieren. Die simulierte Schadenslage wurde durch die charakteristischen Modellgrößen Virulenz, Vulnerabilität und Resistenz der Akteure sowie die geografische Reichweite einer Kontamination quantifiziert. Insbesondere galt es, den Einfluss des Handels zwischen den Molkereien auf die räumliche Ausbreitung einer Kontamination abzuschätzen. Die Grundlage für die durchgeführte Modellierung bildeten 500 Handelsnetzwerke, die 61,43% der existierenden Warenflüsse von Konsummilch in Deutschland abbilden. Diese Netzwerke umfassen variierende Handelsbeziehungen zwischen 294 Milcherzeugern, 80 Molkereien und 12223 Konsumenten. Anderseits wurde ein Managementplan für Entscheidungsträger konzipiert, aus welchem Überwachungsmaßnahmen zur Minimierung der Schadenslage abgeleitet wurden. Die Modellergebnisse zeigen Akteure und Strukturen auf, die fördernd für die Ausbreitung einer hypothetischen Kontamination in der Milchwirtschaft sind. Zum einen kann bei stattfindendem Handel zwischen den Molkereien das Risiko für den Verbraucher im Mittel bis zu dreimal höher sein mit der hypothetisch kontaminierten Milch beliefert zu werden bzw. die Ausbreitung durch den Milcherzeuger kann im Mittel bis zu viermal höher sein, als ohne diesen Handel. Zum anderen zeigt der erstellte Managementplan, dass unter dem vorgegebenen Szenario, Kontrollmaßnahmen für 40% der Milcherzeuger eingeleitet werden müssten, um die Schadenslage zu minimieren

How to Measure Food Safety? A Review of Relevant Literature

Approaches for prospective estimation of economic consequences until the last stage of the agri-food chain can rarely be found. Hence, we see the necessity of working out a conceptual assessment model for cost-benefit evaluation of food safety measures along the supply chain. Based on the findings of a thorough literature study a preliminary conceptual framework was developed. The purpose of the framework is to combine most relevant aspects of agri-food production, quality management, risk-analysis and regulatory impact assessment that have to be considered during in the course of an economic assessment of food safety

Microbiota of the Gut-Lymph Node Axis: Depletion of Mucosa-Associated Segmented Filamentous Bacteria and Enrichment of Methanobrevibacter by Colistin Sulfate and Linco-Spectin in Pigs

Microorganisms are translocated from the gut to lymphatic tissues via immune cells, thereby challenging and training the mammalian immune system. Antibiotics alter the gut microbiome and consecutively might also affect the corresponding translocation processes, resulting in an imbalanced state between the intestinal microbiota and the host. Hence, understanding the variant effects of antibiotics on the microbiome of gut-associated tissues is of vital importance for maintaining metabolic homeostasis and animal health. In the present study, we analyzed the microbiome of (i) pig feces, ileum, and ileocecal lymph nodes under the influence of antibiotics (Linco-Spectin and Colistin sulfate) using 16S rRNA gene sequencing for high-resolution community profiling and (ii) ileocecal lymph nodes in more detail with two additional methodological approaches, i.e., cultivation of ileocecal lymph node samples and (iii) metatranscriptome sequencing of a single lymph node sample. Supplementation of medicated feed showed a local effect on feces and ileal mucosa-associated microbiomes. Pigs that received antibiotics harbored significantly reduced amounts of segmented filamentous bacteria (SFB) along the ileal mucosa (p = 0.048; 199.17-fold change) and increased amounts of Methanobrevibacter, a methanogenic Euryarchaeote in fecal samples (p = 0.005; 20.17-fold change) compared to the control group. Analysis of the porcine ileocecal lymph node microbiome exposed large differences between the viable and the dead fraction of microorganisms and the microbiome was altered to a lesser extent by antibiotics compared with feces and ileum. The core microbiome of lymph nodes was constituted mainly of Proteobacteria. RNA-sequencing of a single lymph node sample unveiled transcripts responsible for amino acid and carbohydrate metabolism as well as protein turnover, DNA replication and signal transduction. The study presented here is the first comparative study of microbial communities in feces, ileum, and its associated ileocecal lymph nodes. In each analyzed site, we identified specific phylotypes susceptible to antibiotic treatment that can have profound impacts on the host physiological and immunological state, or even on global biogeochemical cycles. Our results indicate that pathogenic bacteria, e.g., enteropathogenic Escherichia coli, could escape antibiotic treatment by translocating to lymph nodes. In general ileocecal lymph nodes harbor a more diverse and active community of microorganisms than previously assumed

Microbiota of the Gut-Lymph Node Axis: Depletion of Mucosa-Associated Segmented Filamentous Bacteria and Enrichment of Methanobrevibacter by Colistin Sulfate and Linco-Spectin in Pigs

Microorganisms are translocated from the gut to lymphatic tissues via immune cells, thereby challenging and training the mammalian immune system. Antibiotics alter the gut microbiome and consecutively might also affect the corresponding translocation processes, resulting in an imbalanced state between the intestinal microbiota and the host. Hence, understanding the variant effects of antibiotics on the microbiome of gut-associated tissues is of vital importance for maintaining metabolic homeostasis and animal health. In the present study, we analyzed the microbiome of (i) pig feces, ileum, and ileocecal lymph nodes under the influence of antibiotics (Linco-Spectin and Colistin sulfate) using 16S rRNA gene sequencing for high-resolution community profiling and (ii) ileocecal lymph nodes in more detail with two additional methodological approaches, i.e., cultivation of ileocecal lymph node samples and (iii) metatranscriptome sequencing of a single lymph node sample. Supplementation of medicated feed showed a local effect on feces and ileal mucosa-associated microbiomes. Pigs that received antibiotics harbored significantly reduced amounts of segmented filamentous bacteria (SFB) along the ileal mucosa (p = 0.048; 199.17-fold change) and increased amounts of Methanobrevibacter, a methanogenic Euryarchaeote in fecal samples (p = 0.005; 20.17-fold change) compared to the control group. Analysis of the porcine ileocecal lymph node microbiome exposed large differences between the viable and the dead fraction of microorganisms and the microbiome was altered to a lesser extent by antibiotics compared with feces and ileum. The core microbiome of lymph nodes was constituted mainly of Proteobacteria. RNA-sequencing of a single lymph node sample unveiled transcripts responsible for amino acid and carbohydrate metabolism as well as protein turnover, DNA replication and signal transduction. The study presented here is the first comparative study of microbial communities in feces, ileum, and its associated ileocecal lymph nodes. In each analyzed site, we identified specific phylotypes susceptible to antibiotic treatment that can have profound impacts on the host physiological and immunological state, or even on global biogeochemical cycles. Our results indicate that pathogenic bacteria, e.g., enteropathogenic Escherichia coli, could escape antibiotic treatment by translocating to lymph nodes. In general ileocecal lymph nodes harbor a more diverse and active community of microorganisms than previously assumed

MEASURING THE COSTS OF FOODBORNE DISEASES: A REVIEW AND CLASSIFICATION OF THE LITERATURE

The food scandals and foodborne disease outbreaks in recent years have increased the demand for food safety and have led policy makers once more to tighten the safety regulations in the food supply chain. Obviously, an adequate balance between the costs of foodborne diseases and the costs and benefits of improved food safety is not static but time-varying and depends very much on specific situations. Given the complexity of an economic assessment of food safety, it is not surprising that the literature in this field mainly analyses particular stages but not the complete food supply chain from the farm to the consumer. This paper focuses on the costs of foodborne diseases and aims to review and classify the existing literature along a set of certain evaluation criteria. Our main findings are that most studies so far have been conducted in the USA and the UK. The reviewed studies consider mainly the consumption level of the supply chain, focus on tangible costs, examine budgetary costs and costs of individuals, and make use of the cost-of-illness approach

How to Measure Food Safety? A Review of Relevant Literature

Approaches for prospective estimation of economic consequences until the last stage of the agri-food chain can rarely be found. Hence, we see the necessity of working out a conceptual assessment model for cost-benefit evaluation of food safety measures along the supply chain. Based on the findings of a thorough literature study a preliminary conceptual framework was developed. The purpose of the framework is to combine most relevant aspects of agri-food production, quality management, risk-analysis and regulatory impact assessment that have to be considered during in the course of an economic assessment of food safety

Comparison of Defined Course Doses (DCDvet) for Blanket and Selective Antimicrobial Dry Cow Therapy on Conventional and Organic Farms

Antimicrobial use in livestock production is a controversial subject. While antimicrobials should be used as little as possible, it is still necessary, from both an animal health and welfare point of view, to treat infected animals. The study presented here aimed to analyse antimicrobial use on Austrian dairy farms by calculating the number of Defined Course Doses (DCDvet) administered per cow and year for dry cow therapy. Antimicrobial use was analysed by production system and whether farmers stated that they used blanket dry cow therapy (i.e., all cows in the herd were treated) or selective dry cow therapy (i.e., only cows with a positive bacteriological culture or current/recent history of udder disease were treated). A statistically significant difference (p < 0.001) was determined between antimicrobial use for blanket (median DCDvet/cow/year: 0.88) and selective dry cow therapy (median DCDvet/cow/year: 0.41). The difference between antimicrobial use on conventional and organic farms for dry cow therapy as a whole, however, was not statistically significant (p = 0.22) (median DCDvet/cow/year: 0.68 for conventional; 0.53 for organic farms). This analysis demonstrates that selective dry cow therapy leads to a lower overall use of antimicrobials and can assist in a more prudent use of antimicrobials on dairy farms

Prevalence of Virulence Genes and Antimicrobial Resistances in E. coli Associated with Neonatal Diarrhea, Postweaning Diarrhea, and Edema Disease in Pigs from Austria

Increasing numbers of multi-resistant Escherichia (E.) coli from clinical specimens emphasize the importance of monitoring of their resistance profiles for proper treatment. Furthermore, knowledge on the presence of virulence associated genes in E. coli isolates from European swine stocks is scarce. Consequently, a total of 694 E. coli isolated between 2016 and 2018 from diarrheic piglets of Austrian swine herds were investigated. The isolates were tested for their susceptibility to twelve antibiotics using agar disk diffusion test and for the presence of 22 virulence associated genes via PCR. Overall, 71.9, 67.7, and 49.5% of all isolates were resistant to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole, while resistance levels to gentamicin and fosfomycin were 7.7 and 2.0%, respectively. Resistance frequency to ciprofloxacin was higher than in previous studies. Isolates were more likely to be resistant to ampicillin if they were also resistant to ciprofloxacin. No isolate was resistant to meropenem or amikacin. Virulence genes were detected more frequently in isolates expressing hemolytic activity on blood agar plates. The detection rate of faeG was increased in fimH negative isolates. We assume, that hemolytic activity and absence of fimH could be considered as potential indicators for the virulence of E. coli in piglets

The Metabolically Active Bacterial Microbiome of Tonsils and Mandibular Lymph Nodes of Slaughter Pigs

The exploration of microbiomes in lymphatic organs is relevant for basic and applied research into explaining microbial translocation processes and understanding cross-contamination during slaughter. This study aimed to investigate whether metabolically active bacteria (MAB) could be detected within tonsils and mandibular lymph nodes (MLNs) of pigs. The hypervariable V1-V2 region of the bacterial 16S rRNA genes was amplified from cDNA from tonsils and MLNs of eight clinically healthy slaughter pigs. Pyrosequencing yielded 82,857 quality-controlled sequences, clustering into 576 operational taxonomic units (OTUs), which were assigned to 230 genera and 16 phyla. The actual number of detected OTUs per sample varied highly (23-171 OTUs). Prevotella zoogleoformans and Serratia proteamaculans (best type strain hits) were most abundant (10.6% and 41.8% respectively) in tonsils and MLNs, respectively. To explore bacterial correlation patterns between samples of each tissue, pairwise Spearman correlations (rs) were calculated. In total, 194 strong positive and negative correlations |rs| ≥ 0.6 were found. We conclude that (i) lymphatic organs harbor a high diversity of metabolically active bacteria, (ii) the occurrence of viable bacteria in lymph nodes is not restricted to pathological processes and (iii) lymphatic tissues may serve as a contamination source in pig slaughterhouses. This study confirms the necessity of the EFSA regulation with regard to a meat inspection based on visual examinations to foster a minimization of microbial contamination

Detection of Various Streptococcus spp. and Their Antimicrobial Resistance Patterns in Clinical Specimens from Austrian Swine Stocks

Knowledge of pathogenic potential, frequency and antimicrobial resistance patterns of porcine Streptococcus (S.) spp. other than S. suis is scarce. Between 2016 and 2020, altogether 553 S. spp. isolates were recovered from clinical specimens taken from Austrian swine stocks and submitted for routine microbiological examination. Antimicrobial susceptibility testing towards eight antimicrobial substances was performed using disk diffusion test. All isolates from skin lesions belonged to the species S. dysgalactiae subspecies equisimilis (SDSE). S. hyovaginalis was mainly isolated from the upper respiratory tract (15/19) and S. thoraltensis from the genitourinary tract (11/15). The majority of S. suis isolates were resistant to tetracycline (66%), clindamycin (62%) and erythromycin (58%). S. suis isolates from the joints had the highest resistance rates. S. suis and SDSE isolates resistant to tetracycline were more likely to be resistant to erythromycin and clindamycin (p < 0.01). Results show that different species of Streptococcus tend to occur in specific body sites. Nevertheless, a statement whether these species are colonizers or potential pathogens cannot be given so far. High resistance rates of S. suis towards tetracyclines and erythromycin and high recovery rates of S. suis from lung tissue should be considered when treating pigs with respiratory diseases