T.G. Nagaraja

DVM Courses:

• DMP 712. Veterinary Bacteriology and Mycology (3 credit hours): Taught in the Fall semester for Sophomore DVM students. I teach 34 of the 48 lectures
• DMP 713. Veterinary Bacteriology and Mycology Laboratory (1 credit hour): Taught in the Fall semester for Sophomore DVM students. I teach 12 of the 17 laboratory exercises on pathogens of veterinary importance
• AP 747. Veterinary Physiology (8 credit hours): Taught in the Spring semester for Freshman DVM students. I teach the section on Ruminant Digestive Physiology (9 lectures)

Graduate Courses:

• ASI/DMP 820. Rumen Metabolism (3 credit hours): Metabolism, absorption, digestion, and passage of nutrients in the rumen; factors affecting the environment of the rumen; certain aspects of rumen function and dysfunction; techniques used in rumen research. This course is taught in the Spring semester of even-numbered years for graduate students in Animal Sciences, Microbiology, Veterinary Medicine and Agronomy
• DMP 925. Rumen Microbiology (3 credit hours): Lectures dealing with the microorganisms of the rumen, their habitat, diversity, structure, interactions, and biochemical activities. Techniques for enumeration, isolation and identification of ruminal microorganisms. This course is taught in the Spring semester of odd-numbered years for graduate students in Animal Sciences, Microbiology, Veterinary Medicine and Agronomy.

My research interest is in the field of Gut Microbiology of animals, particularly of the rumen of cattle. The investigations have focused on the role of microbes in ruminal function and dysfunction, particularly in animals fed high-grain diets. My research is a blend of basic and applied studies and involves collaborative interaction with Epidemiologists, Food Microbiologists, Molecular Biologists, Production Animal Specialists, Ruminant Nutritionists, and Pathologists.

Currently, my laboratory is involved in the following research areas:

1. Preharvest Food safety
   

   The primary focus is on the ecology of foodborne pathogens, particularly on Shiga toxin-producing Escherichia coli (STEC), both O157 and non-O157 serogroups, Salmonella, and Campylobacter, and antimicrobial resistance of gut bacteria in beef cattle. The long-term goal is to enhance food safety and public health by developing strategies to identify and mitigate food-borne pathogens and antimicrobial resistance in beef and swine production systems.
   
   

   Shiga toxin-producing E. coli. Healthy cattle are a major reservoir of STEC in which the organisms reside primarily in the hindgut. These bacteria are shed in the feces, which then serve as a source of contamination of beef, produce, and recreational and drinking water. Research efforts in the past have focused primarily on STECO157:H7. Recently, there is increased recognition that six other STEC serogroups, O26, O45, O103, O111, O121, and O145, which are also of major public health concern. The aims of our continuing research are to develop and validate improved methods for the detection of STEC in cattle feces and environmental samples, to improve our understanding of the natural ecology of STEC in cattle operations, and to identify and test on-farm interventions. Research efforts to identify factors affecting gut persistence and fecal shedding of STEC could lead to management strategies and production practices that could be manipulated to reduce the prevalence of E. coli O157 in beef cattle.
   
   

   Salmonella :The presence of Salmonella in beef cattle production systems can cause serious adverse effects in cattle as well as humans. In cattle, Salmonella can affect morbidity, mortality, production efficiency, and the economic well-being of cattle producers. Salmonella is a common cause of gastroenteritis in humans with outbreaks and infections often linked to consumption of contaminated beef, milk, water or other foods. The emergence and dissemination of multi-drug resistant Salmonella are also of major public health concerns. The research goals are to understand the ecology, characteristics, and virulence potential of Salmonella in cattle.
   
   

   Campylobacter : The species of Campylobacter cause enteritis and in some instances abortion in cattle. However, the importance of Campylobacter as a food borne pathogen that can cause sporadic cases and outbreaks of human Campylobacter infections. In the past, human infections have chiefly been attributed to poultry sources. Recently, cattle are being recognized as an important source of food contamination. The research goals are to understand the ecology, virulence potential and antimicrobial resistance patterns of Campylobacter in cattle.
   
   

   Antimicrobial Resistance : The use of antimicrobials in animal agriculture is considered to be a major contributor to the emergence and spread of antimicrobial resistance in the environment. The concern over antimicrobial resistance has important consequences for public health and the food animal industries, including restricted access to global markets. Additionally, there is increased interest in the use of antibiotic alternatives, such as heavy metals (copper and zinc), probiotics, essential oils, etc. in swine and beef cattle production systems. Research goals include monitoring prevalence, amplification, and dissemination of antimicrobial resistance genes and bacteria that carry resistance genes in beef cattle and swine production systems and to assess the contribution or mitigation of antibiotic alternatives on antimicrobial resistance of gut bacteria in cattle and swine.

2. Liver abscesses in feedlot cattle
   
   Liver abscesses are a major cause of liver abnormalities of feedlot cattle at slaughter, and represent a significant economic liability to the producer, the packer, and ultimately to the consumer of beef. Liver abscesses are generally a sequela to ruminal acidosis and rumenitis in cattle fed diets high in readily-fermentable carbohydrates and low in roughages; thus the term ‘acidosis-rumenitis-liver abscess complex’. The primary causative agent is Fusobacterium necrophorum, a Gram negative anaerobe and a ruminal bacterium that crosses ruminal wall to reach the liver via portal circulation to cause abscesses. My laboratory focusses on the bacterial flora of liver abscesses, virulence factors and pathogenic mechanism of Fusobacterium necrophorum, with the long term goal of developing an efficacious vaccine.

1. US Patent No.5,455,034(Date of issue Oct 3, 1995). Fusobacterium necrophorum Lukotoxoid Vaccine (Method of preparing the vaccine).
   Inventors: Nagaraja, T. G. and M. M. Chengappa
2. US Patent No.5,492,694(Date of issue Feb 20, 1996). Fusobacterium Leukotoxoid vaccine (for prevention of liver abscesses and foot rot in cattle and sheep).
   Inventors: Nagaraja, T. G. and M. M. Chengappa.
3. US Patent Number 5,861,162 (Date of issue Jan 19, 1999). Multivalent Inocula for Lessening Incidence of Liver Abscesses in Cattle.
   Inventors: T. G. Nagaraja and M. M. Chengappa.
4. US Patent Number 6,669,940 (Date of issue Dec 30, 2003). Recombinant Fusobacterium necrophorum leukotoxin vaccine and preparation thereof.
   Inventors: T. G. Nagaraja, G. C. Stewart, S. Narayanan, and M. M. Chengappa.
5. US Patent Number 7,449,312 (Date of issue Nov 11, 2008). Recombinant Fusobacterium necrophorum leukotoxin vaccine and preparation thereof.
   Inventors: T. G. Nagaraja, G. C. Stewart, S. Narayanan, and M. M. Chengappa
6. US Patent Number 9,308,247 (Date of issue April 12,, 2016). Composition and methods for detecting, treating, and protecting against Fusobacterium infections
   Inventors: Narayanan, S., Amit Kumar, T. G. Nagaraja, and M. M. Chengappa

Book Chapters (Total: 18)

1. Nagaraja, T. G. 2016. Microbiology of the Rumen. p. 39-61. In: Rumenology. D. D. Mille, M. D. B. Arrigoni, and R. D. L. Pacheco (ed.), Springer International Publishing, Switzerland.
2. Nagaraja, T. G. 2015. Hepatic Abscesses. P. 859-861. In: Large Animal Internal Medicine. B. P. Smith (ed.), 5 th edition, Mosby Elsevier, St. Louis, MO.
3. Nagaraja, T. G. 2013. Arcanobacterium. p 203-205. In: Veterinary Microbiology. D. S. McVey, M. Kennedy, and M. M. Chengappa (eds.), Wiley-Blackwell, Ames, IA.
4. Nagaraja, T. G. 2013. Corynebacterium. p 212-217. In: Veterinary Microbiology. D. S. McVey, M. Kennedy, and M. M. Chengappa (eds.), Wiley-Blackwell, Ames, IA.
5. Nagaraja, T. G. 2013. Gram Negative Anaerobes,p 228-237. In: Veterinary Microbiology. D. S. McVey, M. Kennedy, and M. M. Chengappa (eds.), Wiley-Blackwell, Ames, IA.
6. Jacob, M. E., J. T. Fox, and T. G. Nagaraja. 2012. Prevalence of food-borne pathogens in organic beef. p 287-300. In: Organic Meat Production and Processing. S. C. Ricke, E. J. Van Loo, M. G. Johnson, and C. A. O’Bryan (eds.) Wiley-Blackwell, Ames, IA.
7. Jacob, M. E. and T. G. Nagaraja. 2012. Use of direct-fed microbials as a preharvest food safety intervention in cattle. p 189-202. In: Direct-Fed Microbials and Probiotics for Animals: Science and Mechanisms of Action. T. R. Callaway and S. C. Ricke (eds.) Springer Publ., NY.
8. Hampson, D. J., T. G. Nagaraja, R. M. Kennan, and J. I. Rood. 2010.Gram negative anaerobes. P. 513-526. In: Pathogenesis of Bacterial Infections in Animals. Gyles, G. L., J. F. Prescott, J. G. Songer, and C. O. Thoen (eds.), Blackwell Publishing, Ames, IA.

Review Papers (Total: 14)

1. Garcia, M., B. J. Bradford^*, and T. G. Nagaraja* 2017. Invited Review: Ruminal Microbes, Microbial Products, and Systemic Inflammation. Prof. Anim. Sci. 33:635-650.
2. Amachawadi, R. G. and T. G. Nagaraja*. 2016. Liver abscesses in cattle: A Review of Incidence in Holsteins and of bacteriology and vaccine approach to control in feedlot cattle. J. Anim. Sci. 94:1620-1632.
3. Krause, D. O., T. G. Nagaraja, A. D. G. Wright, and T. R. Callaway*. 2013. BOARD INVITED REVIEW: Rumen microbiology: Leading the way in microbial ecology. J. Anim. Sci. 91:331-341.
4. Jacob, M. E., T. R. Callaway and T. G. Nagaraja*. 2009. Dietary Interactions and Interventions Affecting Escherichia coli O157 Colonization and Shedding in Cattle. Foodborne Path. Dis. 6:785-792.
5. Tadepalli, S., S. K. Narayanan, G. C. Stewart, M. M. Chengappa, and T. G. Nagaraja*. 2009. Fusobacterium necrophorum: A ruminal bacterium that invades liver to cause abscesses in cattle. Anaerobe 15:36-43.
6. Jacob, M. E., Fox, J. T., S. Reinstein, and T. G. Nagaraja*. 2008. Antimicrobial Susceptibility of Foodborne Pathogens in Organic or Natural Production Systems: An Overview. Foodborne Path. Dis., 5:720-730.
7. Fox, J. T., S. Reinstein, M. E. Jacob, and T. G. Nagaraja*. 2008. Niche Marketing Production Practices for Beef Cattle in the United States and Prevalence of Foodborne Pathogens. Foodborne Path. Dis., 5:1-12.
8. Nagaraja, T. G*. and E. C. Titgemeyer. 2007. Ruminal acidosis in Beef cattle: The current microbiological and nutritional outlook. J. Dairy Sci., 90(E. Suppl. 1):E17-E38.
9. Nagaraja , T. G*., S. K. Narayanan, G. C. Stewart, and M. M. Chengappa. 2005 Fusobacterium necrophorum infections in animals: Pathogenesis and pathogenic mechanisms. Anaerobe, 11:238-246.

Refereed Publications (Total=202; *Corresponding Author)

Shiga toxin-Producing E. coli

1. Noll, L. W., J. N. Worley, X. Yang, P. B. Shridhar, J. B. Ludwig, X. Shi,J. Bai,D. Caragea, J. Meng, and T. G. Nagaraja*. 2018. Comparative genomics reveals differences in mobile virulence genes of Escherichia coli O103 pathotypes of bovine fecal origin. PLoS One. In Press
2. Shridhar, P. B., L. W. Noll, C. A. Cull, X. Shi, X., N. Cernicchiaro, D. G. Renter, D.G., J. Bai, and T. G, Nagaraja*. 2017. Spiral plating method to quantify the six major non-O157 E. coli serogroups in cattle feces. J. Food Prot. 80:848-856.
3. Noll, L. W., J. N. Worley, X. Yang, P. B. Shridhar, J. Bai, J. Meng, D. Caragea, and T. G. Nagaraja*.^. 2017. Draft genome sequences of enteropathogenic Escherichia coli O103 strains isolated from feces of feedlot cattle. Genome Announc. 5:e00387-17.
4. Noll, L. W., J. N. Worley, X. Yang, P. B. Shridhar, J. Bai, J. Meng, D. Caragea, and T. G. Nagaraja*.^. 2017. Draft genome sequences of enterohemorrhagic Escherichia coli O103:H2 strains isolated from feces of feedlot cattle. Genome Announc. 5:e00094-17.
5. Shridhar, P. B., C. Siepker, L. W. Noll, X. Shi, T. G. Nagaraja* and J. Bai*. 2017. Shiga toxin subtypes of non-O157 Escherichia coli serogroups isolated from cattle feces. Front. Cell. Infect. Microbiol. 7:121.
6. Shridhar, P. B., I. R. Patel, J. Gangiredla, M. K. Mammel, L. W. Noll, X. Shi, J. Bai, C. A. Elkins, N. Strockbine, and T. G, Nagaraja*. 2017. Draft genome sequences of Escherichia coli O104 strains of bovine and human origin. Genome Announc. 5:e00630-17.
7. Noll, L. W., W. C. Baumgartner, P. B. Shridhar, C. A. Cull, D. M. Dewsbury, X. Shi, B. An, N. Cernicchiaro, D. G. Renter, and T. G. Nagaraja*. 2016. Pooling of immunomagnetic separation beads does not affect sensitivity of detection of six serogroups of Shiga toxin-producing Escherichia coli in cattle feces. J. Food Prot. 79:59-65.
8. Shridhar, P. B., L. W. Noll, X. Shi, B. An, N. Cernicchiaro, D. G. Renter, T. G. Nagaraja*, and J. Bai*. 2016. Multiplex real-time PCR assays for the detection and quantification of the six major non-O157 Escherichia coli serogroups in cattle feces. J. Food Prot. 79:66-74.
9. Toro, M., G. Cao, L. Rump, T.G. Nagaraja, J. Meng, and N. G. Escalona*. 2015. Draft genome sequences of 64 strains of non-O157:H7 Shiga toxin-producing Escherichia coli. Genome A, 3:e01067-15.
10. Noll, L. W., P. B. Shridhar, D. M. Dewsbury, X. Shi, N. Cernicchiaro, D. G. Renter and T. G. Nagaraja*. A comparison of culture- and PCR-based methods to detect six non-O157 serogroups of Shiga toxin-producing Escherichia coli in cattle feces. PLoS One, 10:e0135446.
11. Noll, L. W., P. B. Shridhar, X. Shi, B. An, N. Cernicchiaro, D. G. Renter, T. G. Nagaraja*, and J. Bai*.2015. A four-plex real-time PCR assay, based on rfbE, eae, stx1 and stx2 genes, for the detection and quantification of Escherichia coli O157 in cattle feces. Foodborne Path. Dis. 12:787-794
12. Paddock Z. D, D. G. Renter, C. A. Cull, J. Bai, and T. G. Nagaraja*. 2014. Escherichia coli O26 in feedlot cattle: Fecal prevalence, isolation, characterization and effects of an E. coli O157 vaccine and a direct-fed microbial. Foodborne Pathog Dis. 11: 186-193
13. Paddock, Z. D., J. Bai*, X. Shi, D. G. Renter, and T. G. Nagaraja*. 2013. Detection of Escherichia coli O104 in the feces of feedlot cattle by a multiplex PCR assay designed to target major genetic traits of the virulent hybrid strain responsible for the 2011 German outbreak. Appl. Environ. Microbiol. 79:3522-3525.
14. Paddock, Z. D, D. G. Renter, X. Shi, C. R. Krehbiel, B. DeBey, and T. G. Nagaraja* 2013. Effects of feeding dried distillers grains with supplemental starch on fecal shedding of Escherichia coli O157:H7 in experimentally inoculated steers^. J. Anim. Sci. 91:1362-1370.

Antimicrobial Resistance

1. Smith, A.B., D. G. Renter, N. Cernicchiaro, X. Shi, J. S. Nickell, D. J. Keil, and T. G. Nagaraja. 2017. A randomized trial to assess the effect of fluoroquinol metaphylaxis on the fecal prevalence and quinolone susceptibilities of Salmonella and Campylobacter in feedlot cattle. Foodborne Pathog. Dis. 14: 600-607.
2. Smith, A. B., D. G. Renter, N. Cernicchiaro, X. Shi, and T. G. Nagaraja. 2016. Prevalence and quinolone susceptibilities of Salmonella isolated from the feces of preharvest cattle within feedlots that used a fluorqionolone to treat bovine respiratory disease. Foodborne Pathog. Dis., 13:1-6.
3. Feldpausch, J. A., R. G. Amachawadi, M. D. Tokach, H. M. Scott, T. G. Nagaraja, S. S. Dritz, R. D. Goodband, J. C. Woodworth, and J. M. DeRouchey. 2016. Effects of dietary copper, zinc, and ractopamine HCl on finishing pig growth performance, carcass characteristics, and antimicrobial susceptibility of enteric bacteria. J. Anim. Sci., 94(8): 3278-3293.
4. Aperce, C. C., R. G. Amachawadi, C. L. Krueger-Van Bibber, T. G. Nagaraja, H. M. Scott, J. Vinasco-Torre, and J. S. Drouillard. 2016. Effects of menthol supplementation in feedlot cattle diets on the fecal prevalence of antimicrobial resistant Escherichia coli. PLoS One. 11(12):e0168983.
5. Amachawadi, R. G., H. M. Scott*, C. Aperce, J. Vinasco, J. S. Drouillard, and T. G. Nagaraja. 2015. Effects of in-feed copper and tylosin supplementations on copper and antibiotic resistance in fecal enterococci of feedlot cattle. J. Appl. Microbiol. 118:1287-1297.
6. Amachawadi, R. G., H. M. Scott*, S. Nitikanchana, J. Vinasco, M. D. Tokach, S. S. Dritz, J. L. Nelssen, R. D. Goodband and T. G. Nagaraja. Nasal carriage of mecA-positive methicillin-resistant Staphylococcus aureus in pigs exhibits dose-response to zinc supplementation. Foodborne Path. Dis. 12:159=163.
7. Amachawadi, R. G., N. W. Shelton, X. Shi, J. Vinasco, S. S. Dritz, M. D. Tokach, J. L. Nelssen, H. M. Scott, and T. G. Nagaraja*. 2011. Selection of tcrB gene mediated copper resistant fecal enterococci in pigs fed diets supplemented with copper. Appl. Environ. Microbiol. 77:5597-5603.
8. Jacob, M. E., J. T. Fox, T. G. Nagaraja, J. S. Drouillard, R. G. Amachawadi, S. K. Narayanan*. 2010. Effects of Feeding elevated concentrations of supplemental copper and zinc on antimicrobial susceptibilities of fecal bacteria in feedlot cattle. Foodborne Path. Dis. 7:643-648.

Hepatic Abscesses

1. Amachawadi, R. G., T. J. Purvis, B. V. Lubbers, J. W. Homm, C. L. Maxwell, and T. G. Nagaraja*. 2017. Bacterial flora of liver abscesses in crossbred beef cattle and Holstein steers finishing diets with or without tylosin. J. Anim. Sci.95:3425-3434.
2. Amachawadi, R. G. and T. G. Nagaraja*. 2015. First report of anaerobic isolation of Salmonella enterica from liver abscesses of feedlot cattle. J. Clin. Microbiol. 53:3100-3101.
3. Kumar, A., S. Menon, T. G. Nagaraja, and S. Narayanan*.2015. Identification of an outer membrane protein of Fusobacterium necrophorum subsp. necrophorum that binds with high affinity to bovine endothelial cells. Vet. Microbiol 176:196-201.
4. Calcutt, M. J., M. F. Foecking,T. G. Nagaraja,G. C. Stewart. 2014. Draft genome sequence of Fusobacterium necrophorum subsp. funduliforme bovine liver abscess isolate B35. GenomeA, 2:e00412-00414.
5. Kumar A., E. Gart, T. G. Nagaraja, and S. Narayanan*. 2013. Adhesion of Fusobacterium necrophorum to bovine endothelial cells is mediated by outer membrane proteins. Vet Microbiol. 162:813-818
6. Kumar A., G. Peterson, T. G. Nagaraja, and S. Narayanan*. 2012. Outer membrane proteins of Fusobacterium necrophorum subsp. necrophorum and subsp. funduliforme. J. Basic Microbiol. 00:1-6.