B.A. (1975) Austin College, Sherman, Texas
Ph.D. (1981) University of California, Berkeley
We are primarily interested in the
study of virulence, adaptive physiology, ecology, molecular
epidemiology and evolution of bacterial foodborne pathogens.
Our focus is on two systems of substantial current concern
to food safety, Listeria monocytogenes and Campylobacter
jejuni. Sources of food contamination by Listeria are
primarily environmental (although reservoirs remain largely
unknown), whereas Campylobacter is commensal in birds,
and infection commonly involves contaminated poultry products.
Our objective is to employ molecular epidemiologic tools
along with genetic, physiologic and pathogenesis approaches
to identify and characterize lineages of special relevance
to food safety, including the unique clonal lineages that
have been implicated in epidemics of foodborne listeriosis.
Listeria can persist in biofilms and grow at low
temperatures, and we are investigating the molecular basis
underlying cold and freeze tolerance, and biofilm establishment
and persi stence of the pathogen. These processes are also
being studied with Campylobacter, which is capable
of persistence (albeit not growth) in refrigerated foods,
esp. poultry. Campylobacter is a genetically highly
variable microorganism, presenting special opportunities
and challenges to the study of the evolution of virulent
strains, and their adaptation to different hosts, such as
poultry, other meat animals, and humans.