Tuberculosis (TB), caused by the bacterial organism Mycobacterium tuberculosis, pose a major threat to public health, especially in middle and low-income countries. Worldwide in 2018, approximately 10 million new cases of TB were reported to the World Health Organization (WHO). There are a limited number of medications available to treat TB; additionally, multi-drug resistant TB and extensively-drug resistant TB strains are becoming more prevalent. As a result of various factors, such as increased costs of developing new medications and adverse side effects from current medications, researchers continue to evaluate natural compounds for additional treatment options. These substances have the potential to target bacterial cell structures and may contribute to successful treatment. For example, a study reported that green and black tea, which contains epigallocatechin gallate (a phenolic antioxidant), may decrease the risk of contracting TB in experimental subjects; cumin (a seed from the parsley plant) has been demonstrated to improve the bioavailability of rifampicin, an important anti-TB medication, and propolis (a natural substance produced by honeybees) has been shown to improve the binding affinity of anti-TB medications to bacterial cell structures. In this article, we review the opportunistic pathogen M. tuberculosis, various potential therapeutic targets, available therapies, and natural compounds that may have anti-TB properties. In conclusion, different natural compounds alone as well as in combination with already approved medication regimens should continue to be investigated as treatment options for TB.

Salmonella spp. are important zoonotic pathogens in humans and animals. A longitudinal study was conducted at the Iowa State University's campus (at the Dairy/Animal Science Education and Discovery Facility) to observe change in Enterobacteriaceae (specifically Salmonella) before and after the placement of dairy livestock. To our knowledge, this is the first study that evaluated environmental changes of Gram-negative organisms in a new dairy farm environment. Environmental samples were taken using drag swabs and immediately processed in the laboratory using phenotypic methods (replica plating, the BBL Crystal Identification System for enteric/nonfermenter organisms™, and plating on specialized media/broths). Genotypic methods were also used (BAX PCR™ and pulsed-field gel electrophoresis). Organisms identified as Salmonella were sent to the National Veterinary Services Laboratory (Ames, IA) for confirmatory serotyping. Resistance to antibiotics (ampicillin, nalidixic acid, and tetracycline) was determined by replica plating of Enterobacteriaceae and Salmonella isolates using the guidelines of the National Antimicrobial Resistance Monitoring System and Clinical and Laboratory Standards Institute. The microflora of Enterobacteriaceae changed as cattle were introduced and as time progressed. Additionally, multidrug-resistant isolates began to appear immediately after cattle were introduced (multidrug-resistant isolates were rare prior to introduction of livestock). Variables such as temperature and humidity did not affect the proliferation of bacterial organisms. Seventeen Salmonella isolates were identified as Salmonella London and three isolates as Salmonella Montevideo. Based on pulsed-field gel electrophoresis-generated dendrograms, it is likely that 17 Salmonella London isolates and 3 Salmonella Montevideo isolates are clonal.

Enterococci are Gram-positive, facultative anaerobic cocci. They are found in many environments (including milk and dairy products, vegetables, plants, cereals, and meats). Enterococci are considered commensal organisms, but can also be opportunistic pathogens associated with morbidity and mortality of humans and animals. A longitudinal study of antibiotic resistance of Enterococcus to ampicillin, erythromycin, and tetracycline was conducted on an academic teaching farm. Environmental samples were collected by drag swabs at select locations prior to and after the introduction of livestock. All samples were initially processed and screened with specialized media, and then replica plated on tryptic soy agar containing a predetermined amount of antibiotic. There was some variation in the quantity of bacterial and antibiotic-resistant colonies; however, resistance to tetracycline was extremely high. The increases of too numerous to count populations were not time-dependent and appeared consistently after the placement of cows. There is little information on the prevalence and epidemiology of antibiotic resistance of Enterococci outside of the hospital setting, including on dairy farms. Longitudinal studies are important in providing insight into the dynamics of establishment and proliferation of bacteria and of antibiotic resistance.

Chapter 1. General Introduction Introduction Thesis Organization References Literature Review References Chapter 2. The establishment and proliferation of antibiotic-resistant Campylobacter on a new dairy farm environment prior to and after the placement of dairy cattle Abstract Introduction Materials and Methods Results and Discussion Conclusion Acknowledgements Chapter 3. A longitudinal study of the establishment and proliferation of Enterococcus on a dairy farm Abstract Introduction Materials and Methods Results and Discussion Conclusion Acknowledgements Chapter 4. The establishment of Enterobacteriaceae and Salmonella london in a new dairy farm environment Abstract Introduction Materials and Methods Results and Discussion Conclusion Acknowledgements Chapter 5. General conclusions General Discussion Recommendations for Future Research References Appendix of the Dairy/Animal Science Education Facility Acknowledgements

CHAPTERl.GENERALINTRODUCTION 1 CHAPTER 2. HISTORY OF BIOLOGICAL WARFARE Background Biological Warfare during the Middle Ages Exploration of the "New World" World Wars I and II 7 Post World War II BW activities by the United States 11 Alleged BT activities during the Korean War 14 Microbial and BW Stimulants during the 1950's and 1960's 19 Bacterial Organisms Proposed In BW Use by The CDC's Strategic Working Group Anthrax Plague Tularemia Clostridium botulinum toxin Smallpox Viral Hemorrhagic Fever Ebola and Marburg Viruses Overview of Salmonella CHAPTER 2. OVERVIEW OF MOLECULAR SUBTYPING CHAPTER 3. PFGE EXPERIMENTS Materials and Methods Preparation of Chromosomal DNA Restriction endonuclease digestion and PFGE Results Discussion 110 Conclusions 111 iv CHAPTER 4. A Three-Year Study (2001-2003) of Bioterrorism Preparedness in State Health Departments: Accomplishments and Dilemmas Sullllilary Article (In MMWR format) Discussion Conclusions APPENDIX 1. Resistance if Salmonella isolates tested APPENDIX 2. Grouping of antibiotic resistance profiles APPENDIX 3. Serotyping, PFGE profiles and antibiotic susceptibility testing