Dr. Bessen’s research focuses on group A beta-hemolytic streptococci (Streptococcus pyogenes). Although S. pyogenes infection can produce serious illness, most often it causes only a mild disease at superficial tissue sites - the oropharynx (strep throat) or epidermis (impetigo). Many strains have a distinct preference for either throat or skin. Projects aim to elucidate the genetic organization of S. pyogenes and determine the molecular basis for throat- and skin-specific infections. Due to the use of pathogenic bacteria, ALL TRAINEES MUST BE AT LEAST 18 YEARS OLD.
Dept. of Microbiology & Immunology
Basic Sciences Building
New York Medical College
Valhalla, NY 10595
1990 - 1992, Assistant Professor, Bacterial Pathogenesis & Immunology, Rockefeller University, NY, NY
1992 - 1996, Assistant Professor, Epidemiology & Public Health, Yale University, New Haven, CT
1997 - 2001, Associate Professor, Epidemiology & Public Health, Yale University, New Haven, CT
2002 - 2003, Research Scientist, Ecology & Evolutionary Biology, Yale University, New Haven, CT
2003 - 2004, Associate Professor, Microbiology & Immunology, New York Medical College
2004 - present, Professor, Microbiology & Immunology, New York Medical College
Our research is primarily focused on group A beta-hemolytic streptococci (Streptococcus pyogenes), which are among the most prevalent of bacterial pathogens; humans are its sole biological host. A hallmark feature of S. pyogenes is its molecular and biological diversity among strains. Although S. pyogenes infection can produce serious illness, such as autoimmune and severe invasive disease, most often it causes only a mild disease at superficial tissue sites - the oropharynx (strep throat) or epidermis (impetigo). The throat and skin are the primary tissue reservoirs for S. pyogenes, whereby the organism is most successful in reproductive growth and transmission to new hosts.
It is widely recognized that many strains of S. pyogenes differ in their tissue site preference, giving rise to the concept of distinct throat and skin strains. One of our long-term goals is to determine the molecular basis for throat- and skin-specific infections caused by S. pyogenes. Because throat and skin strains are often separated in time and space, they provide a model for mapping candidate genes that confer tissue tropisms. Gene products under investigation include transcriptional regulators and surface proteins. In addition, the consequences of ecological separation on lateral gene exchange between strains are explored.
Additional studies in our lab investigate antibiotic resistance in S. pyogenes and the unique properties of strains that trigger rheumatic fever.
Tools used in our lab include genomics, transcriptomics, population genetics, targeted mutagenesis, and animal models for disease. For MLST of Streptococcus pyogenes, please see http://pubmlst.org/spyogenes/
Post Graduate Studies: The Rockefeller University
Graduate Degree: Ph.D.
Graduate Degree Institution: The Rockefeller University
Undergraduate Institution: Hampshire College
Bessen, D.E., N. Kumar, G.S. Hall, D.R. Riley, F. Luo, S. Lizano, C.N. Ford, W.M. McShan, S.V. Nyugen, J.C. Dunning Hotopp and H. Tettelin, 2011. Whole genome association study on tissue tropism phenotypes in group A Streptococcus. J. Bacteriol. 193: 6651-63
Willems, R.J.L., W.P. Hanage, D.E. Bessen, and E.J. Feil, 2011. Population biology of Gram-positive bacteria: high-risk clones for dissemination of antibiotic resistance. FEMS Microbiology Reviews, 35: 872-900
Bessen, D.E., W.M. McShan, S.V. Nguyen, A. Shetty, S. Agrawal, and H. Tettelin, 2015. Molecular epidemiology and genomics of group A Streptococcus. Infect. Genet. Evol. 33: 393-418.
Bessen, D.E., 2016. Molecular basis of serotyping and the underlying genetic organization of Streptococcus pyogenes. In: Ferretti JJ, Stevens DL, Fischetti VA, editors. Streptococcus pyogenes: Basic Biology to Clinical Manifestations. eBook: http://www.ncbi.nlm.nih.gov/books/NBK333424/
Bessen, D.E., 2016. Tissue tropisms in group A Streptococcus: what virulence factors distinguish pharyngitis from impetigo strains? Curr. Opin. Infect. Dis. 2016 29:295-303.