D. Scott Merrell ('14)

(Speaker Term: 7/1/12 - 6/30/14)

Uniformed Services University
Department of Microbiology and Immunology
4301 Jones Bridge Road
Bethesda, MD  20814   

Phone: 301-295-1584
Fax: 301-295-3773   
E-mail: douglas.merrell@usuhs.edu    
Speaker’s URL: http://www.usuhs.mil/faculty/douglasmerrell-mic.html   


Helicobacter pylori Colonization and Pathogenesis 
H. pylori colonizes the gastric mucosa of approximately 50% of the world’s population and is currently the only bacterium that is classified as a carcinogen.  Not all individuals infected with the pathogen develop cancer; a spectrum of diseases that range from gastritis to ulcers to cancer can occur.  Using animal models of infection and mutant strains of H. pylori, we have identified factors that are important for the process of colonization as well as disease progression.

Transcriptional Regulation by the Ferric Uptake Regulator (Fur)
Iron is a key factor that is required by virtually all life forms.  However, despite the essential nature of this metal, excess iron is toxic to cells due to the production of reactive oxygen species. Thus, there is a delicate balance between acquiring sufficient iron for survival while still maintaining levels that are not lethal.  In many bacterial species, this balance is achieved through the activity of a transcriptional regulator known as Fur.  The activity of the Fur protein is controlled by the amount of intracellular iron that is available to bind to the protein.  We are studying the process of Fur regulation in H. pylori, where Fur activities are more complex than in other bacterial systems; Fur can act as an activator or repressor in both its iron-bound and iron-free forms.

Novel Drug Targets to Treat Chronic Infections Caused by H. pylori  
Increasing rates of antimicrobial resistance are a significant problem for the treatment of most infectious diseases.  This is particularly true for H. pylori, which requires a complex 14-day treatment schedule that involves the use of three separate drugs.  Despite the need for new classes of antibiotics, advances in this area have been slow.  Thus, we are investigating the use of novel synthetic antimicrobial peptides as well as other compounds as a means of treating H. pylori infection.          

Molecular Epidemiology Related to Virulence Factor Polymorphisms and Disease Progression
H. pylori infected individuals develop a range of possible gastric diseases that can be mild (gastritis) to severe (adenocarcinoma).  The exact reason for this disparity in disease etiology is not completely defined, but likely involves host, environmental and microbial factors.  Several lines of research have shown that numerous H. pylori virulence factors show a high degree of variability.  We have characterized the role of this variability in disease progression using a large collection of clinical samples obtained from South Korean patients.  This work has identified particular polymorphisms in virulence factors that are associated with the development of gastric cancer.                                     


Born and raised in rural Bald Knob, Arkansas, D. Scott Merrell (Scotty) left the south to complete his Ph.D. studies at Tufts Medical School and conduct postdoctoral training at Stanford University.  He is currently an Associate Professor in the Department of Microbiology and Immunology at Uniformed Services University in Bethesda, Maryland.  Intrigued by stress response and how bacteria manage to colonize in inhospitable environments, Scotty’s research group studies colonization and virulence factors of the gastric pathogen Helicobacter pylori.  Scotty is a former “Applied Genomics of Infectious Diseases” ID Training Fellow and Damon Runyon-Walter Winchell Cancer Fund Postdoctoral Fellow.  He received a Merck Irving S. Sigal Memorial Award for excellence in basic research in medical microbiology and infectious diseases.  He is very active in graduate education; he serves on the USU Graduate Education Committee and Executive Committee for the USU Emerging Infectious Disease Graduate Program and has mentored numerous students both in and outside of his lab.


CV is available by request from adempsey@asmusa.org at ASM Headquarters


Primary Division:        B (Microbial Pathogens)

Secondary Division:    D (Microbe-Host Interactions)