BVSc 1994, Madras Veterinary College, India
MS 1997, Kansas State University
PhD 2001, Kansas State University
Diplomate 2001 and 2002, American College of Veterinary Microbiologists (Virology and Immunology)
Diplomate (2007), American College of Veterinary Pathologists
Office: K246 Mosier Hall
Phone: (785) 532-4430
Fax: (785) 532-4039
Dr. Narayanan’s laboratory focuses on two topics:
Pathology of bacterial adherence and injury to host cells.
We are also studying the molecular structure and expression of virulence determinants in Fusobacterium necrophorum. Leukotoxin is one of the major virulence factors of F. necrophorum and plays a critical role in causing multifocal coagulative necrosis of the liver in bovines. The leukotoxin is a large secreted exotoxin (approximately 336 KDa) which causes apoptosis of target cells at lower concentrations and necrosis at higher concentrations. Efforts are also on to elucidate the role of the outer membrane proteins in the adherence of F. necrophorum subspecies to host cells and its effect on animal and human diseases. In-vivo, in-situ and in-vitro studies are focused to understand the virulence of this organism.
Molecular biology of antimicrobial resistance among bacteria.
Antimicrobial resistance is of growing global concern in human and veterinary medicine. Understanding the role of various environmental (ecological) and intrinsic factors that lead to prevalence, amplification and spread of antibiotic resistance is vital. In our lab, we primarily utilize the feedlot industry as a model to understand the role of animal industry in amplification and spread of antimicrobial resistance and virulence genes among food-borne pathogens such as E. coli, Salmonella andEnterococcus. We are interested in identifying non-traditional selection pressures (factors other than exposure to antibiotics) that contribute to multi-drug resistance among intestinal commensals and food-borne pathogens. We have identified acute stress related host catecholamines as an enhancer of conjugative plasmid transfer.
I teach three sophomore veterinary courses: General Pathology (DMP715; Fall), Systemic Pathology (DMP720; Spring) and Cross Course Integration IV (DMP740; Spring). I also teach a graduate course in Pathogenic Mechanisms (DMP 860; Fall).
I coordinate Systemic Pathology Course in which I teach 30 lectures and approximately 35 labs. I primarily focus on the pathologies of cardiovascular, nervous, urinary, reproductive, musculoskeletal and integumentary systems.
I teach 4-6 lectures and approximately 8 to 10 labs in General Pathology course including the pathology of the hemolymphatic system.
Pathogenic Mechanisms is a higher level graduate course designed to understand the mechanisms by which bacteria alter the host systems to their advantage and cause disease. The first half of the course will focus on learning host environment in health and disease and the second half will address bacterial pathogenesis in animal, human and zoonotic diseases.
I perform necropsies and biopsies during summer and fall semesters and enjoy working with students on senior Diagnostic Medicine rotation (DMP785).
Selected peer-reviewed publications
(ªIndicates graduate or undergraduate student and *Indicates the corresponding/senior author)
Kumar, A.a, D. Petersona, R. G. Amachawadi, T. G. Nagaraja and S.K. Narayanan*. Characterization of Fusobacterium necrophorum isolated from llama and alpaca. J. Vet. Diag. Invest. Jul: 25(04):502. 2013.
Kumar, A.a, G. Petersona, T. G. Nagaraja and S.K. Narayanan*. Outer membrane proteins of Fusobacterium necrophorumsubsp. necrophorum and subsp. funduliforme. J. Basic Microbiol. 2013.
Kumar, A.a, E. Garta, T. G. Nagaraja and S.K. Narayanan*. Adhesion of Fusobacterium necrophorum to bovine endothelial cells is mediated by outer membrane proteins. Vet. Microbiol. 2012. [link]
Zhang, Y.a, A. Kumara, P.V. Vadlani* and S.K. Narayanan*. Production of nitrogen-based platform chemical: cyanophycin biosynthesis using recombinant Escherichia coli and renewable media substitutes. Journal of Chemical Technology and Biotechnology. (Dec. 6, 2012). [link]
Unc, A, L. Zurek, G. Petersona, S.K. Narayanan, S.V. Springthorpe, and S.A. Sattar. Microarray assessment of virulence, antibiotic and heavy metal resistance in an agricultural watershed creek. Journal of environmental Quality. 2012. Mar-Apr;41(2):534-43.[link]
Lubbers B.V.a, Peterson G.J., Narayanan S.K., Havel J.A., Coetzee J.F., Apley M.D. Effects of two simulated oxytetracycline dosing regimens on horizontal transfer of antimicrobial resistance plasmids in an in vitro pharmacodynamic model. Am J Vet Res. 2011 Jul;72(7):877-83. [link]
Peterson Ga, Kumar A, Gart E, Narayanan S.K.* Catecholamines increase conjugative gene transfer between enteric bacteria.Microb Pathog. 2011 Jul-Aug;51(1-2):1-8. [link]
Taylor EV, Shi X, Alam MJ, Peterson Ga, Narayanan S.K., Renter DG, Nagaraja TG. Genetic variations in Shiga toxin-producing abilities of bovine and human Escherichia coli O157:H7. Zoonoses Public Health. 2011 May;58(3):185-91. [link]
Peterson Gª, Gerdes B, Berges J, Nagaraja TG, Frye J, Boyle D, and Narayanan SK.* “Development of a Microarray and Multiplex Polymerase Chain Reaction Assays for Identification of Serovars and Virulence Genes in Salmonella enterica of Human or Animal Origin”. J Vet Diagn Invest, 22(4):559-569. 2010. [link]
Peterson Gª, Bai J, Nagaraja TG, and Narayanan SK.* Diagnostic Microarray for human and animal bacterial diseases and their virulence and antimicrobial resistance genes. Journal of Microbiol. Methods. 80(3):223-230. 2010. Featured in: [AZONano] [Nanowerk] [USA Military]
Jacob MEª, Fox JT, Nagaraja TG, Drouillard JS, Amachawadi RG, Narayanan SK*. Effects of feeding elevated concentrations of copper and zinc on the antimicrobial susceptibilities of fecal bacteria in feedlot cattle. Foodborne Pathog. Dis. 7(6):643-8. 2010 [Link]
Thurlow L, Thomas V, Narayanan SK, Olson S, Fleming SD, Hancock L*. Gelatinase Contributes to the Pathogenesis of Endocarditis Caused by Enterococcus faecalis. Infection and Immunity. 78(11):4936-43. 2010.
Amachawadi RGa, Shelton NW, Jacob ME, Shi X, Narayanan SK, Zurek L, Dritz SS, Nelssen JL, Tokach MD, Nagaraja TG*. Occurrence of tcrB, a Transferable Copper Resistance Gene, in Fecal Enterococci of Swine. Foodborne Pathogens and Dis., ahead of print. doi:10.1089/fpd.2010.0540. 2010. [Link]
Coolon JDª, Jones KL, Narayanan SK, Wisely SM*. Microbial ecological response of the intestinal flora of Peromyscus maniculatus and P. leucopus to heavy metal contamination. Mol. Ecol. 19 Suppl 1:67-80. 2010. [Link]
Kim, Y*, Narayanan, SK, Chang KO, Inhibition of influenza virus replication by plant-derived isoquercetin. Antiviral Research 88:227-235. 2010.
Tadepalli Sa, Stewart GC, Nagaraja TG, Narayanan SK*. Human Fusobacterium necrophorum strains have a leukotoxin gene and exhibit leukotoxic activity. J Med. Microbiol. 57(Pt 2):225-231. 2008. [Link]
Tadepalli Sa, Stewart GC, Nagaraja TG, Narayanan SK.* Leukotoxin operon and differential expressions of the leukotoxin gene in bovine Fusobacterium necrophorum subspecies. Anaerobe. 14(1):13-8. 2008. [Link]
Tadepalli Sa, Stewart GC, Nagaraja TG, Jang SS, Narayanan SK*. Fusobacterium equinum possesses a leukotoxin gene and exhibits leukotoxin activity. Vet Microbiol. 127(1-2):89-96. 2008. [Link]
Jacob MEa, Fox JT, Narayanan SK, Drouillard JS, Renter DG, Nagaraja TG.* Effects of feeding wet corn distiller's grains with solubles with or without monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal food-borne pathogenic and commensal bacteria in feedlot cattle. J Anim Sci. 86(5):1182-1190. 2008.
Narayanan SKª, Chengappa MM, Stewart GC, and Nagaraja TG*. Immunogenicity and protective effects of truncated recombinant leukotoxin proteins of Fusobacterium necrophorum in mice. Vet. Microbiol. 93(4) 335-347. 2003.
Narayanan SKª, Stewart GC, Chengappa MM, Willard L, Shuman W, Wilkerson M, and Nagaraja TG*. Fusobacterium necrophorum Leukotoxin Induces Activation and Apoptosis of Bovine Leukocytes. Infect. Immun. 70(8):4609-4620. 2002. [Link]
Narayanan SKª, Nagaraja TG, Chengappa MM, and Stewart GC*. Cloning, Sequencing and Expression of Leukotoxin gene fromFusobacterium necrophorum. Infect. Immun. 69(9):5447-5455. 2001. [Link]
Narayanan SKª, Nagaraja TG, Chengappa MM, and Stewart GC*. Electrophoretic mobility anomalies associated with PCR amplification of the intergenic spacer region between 16S and 23S ribosomal RNA genes of Fusobacterium necrophorum. J. Microbiol. Methods. 46(2):165-169. 2001.
Narayanan SKª, Nagaraja TG*, Staats J, Chengappa MM, and Oberst RD. Biochemical and biological characterizations and ribotyping of Actinomyces pyogenes and Actinomyces pyogenes-like organisms from liver abscesses in cattle. Vet Microbiol. 61(4): 289-303. 1998.
Narayanan SKª, Nagaraja TG*, Wallace N, Staats J, Chengappa MM, Oberst RD. Biochemical and ribotypic comparison ofActinomyces pyogenes and A pyogenes-like organisms from liver abscesses, ruminal wall, and ruminal contents of cattle. Am. J. Vet. Res. 59(3): 271-6. 1998.
Narayanan SKª, Nagaraja TG*, Okwumabua O, Staats J, Chengappa MM, and Oberst RD. Ribotyping to compare Fusobacteriumnecrophorum from bovine liver abscesses, ruminal wall and ruminal contents. Appl. Environ. Microbiol. 63(12): 4671-8. 1997. [Link]