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Kendra Nightingale is originally from a small farming community in western Kansas.  Kendra received a B.S. degree in Agriculture from Kansas State University, where she participated in the undergraduate honors program.  Kendra also holds a M.S. degree from Kansas State University in Food Science, where her research evaluated the use of lactoferrin, a milk-derived protein, to decontaminate and extend the shelf-life of beef products.  Kendra Nightingale completed her PhD at Cornell University in Food Science with a concentration in Food Microbiology and minors in Epidemiology and Microbiology.  Her PhD work probed the molecular epidemiology, ecology, and evolution of the human foodborne and animal pathogen Listeria monocytogenes.  Kendra also completed her postdoctoral training in the Department of Food Science at Cornell University. Kendra joined the Department of Animal Sciences at Colorado State University as an Assistant Professor in 2006.

RESEARCH INTERESTS:
The overall goal of Kendra Nightingale’s research program is to integrate basic and applied research with quantitative epidemiology approaches to reduce the incidence of human foodborne disease.  Kendra’s research interests include both pre- and post-harvest food safety.  Her research uses the facultative intracellular human foodborne and animal pathogen Listeria monocytogenes as a model organism to (i) gain a more comprehensive understanding of the molecular ecology and transmission dynamics of foodborne pathogens throughout the human food chain (ii) identify risk factors that contribute to loading of the human food chain with foodborne pathogens and the subsequent spread of these pathogens along the food continuum using mathematical modeling (iii) probe the molecular evolution and population structure of human foodborne and animal pathogens (iv) define the underlying genetic mechanisms responsible for observed differences in virulence phenotypes and (v) study the pathogenesis of human and animal foodborne diseases.

CURRENT RESEARCH:
Studying the molecular epidemiology and ecology of foodborne pathogens at the pre-harvest food safety level is a critical first step in gaining a more comprehensive understanding of the transmission dynamics of foodborne pathogens throughout the food chain. There is a clear need to integrate classical microbiology, molecular subtyping and quantitative epidemiology to study the transmission of foodborne pathogens to further reduce their prevalence in the food chain and thus the incidence of human foodborne illness. Results from a previous case-control study of ruminant listeriosis (Nightingale et al., 2004; Appl. Environ. Microbiol. and Nightingale et al., 2005; JAVMA) showed that cattle farms may constitute a significant natural reservoir for L. monocytogenes and that L. monocytogenes strains implicated in the majority of human listeriosis epidemics are commonly isolated from cattle farms.  Ongoing research in Kendra’s laboratory is aimed at more precisely defining the transmission characteristics of L. monocytogenes as well as other foodborne pathogens in order to further elucidate the relationship between the presence of foodborne pathogens at different phases along the food chain and human foodborne disease.

Ongoing work in Kendra Nightingale’s research program also includes a collaborative project “Identification and characterization of virulence attenuated Listeria monocytogenes with unique mutations in Internalin A”.  This project involves investigators from Colorado State University, Cornell University, the National Food Processors Association, the FDA, and Health Canada. 

L. monocytogenes is a ubiquitous organism that is commonly isolated from several sources along the human food chain and can persist for extended periods in the environment of food-processing plants.  L. monocytogenes was last projected to cause approximately 2,500 cases of foodborne illness resulting in nearly 500 deaths each year in the US.  While recent data show the incidence of human listeriosis has declined, multi-state listeriosis outbreaks continue to occur and L. monocytogenes remains a significant public health concern.  Current US legislation mandates a “zero-tolerance” policy for the detection of L. monocytogenes in ready-to-eat (RTE) foods and as a result L. monocytogenes represents a considerable problem for the RTE food industry. 

Different L. monocytogenes strains, however, show distinct epidemiological associations. While some strains are overrepresented among human clinical isolates, others are commonly isolated from foods but are rarely linked to human disease.  These observations support the hypothesis that L. monocytogenes strains differ in their virulence and/or transmission characteristics and thus their ability to cause human disease (Nightingale et al., 2005; J. Bacteriol.).  Previous work identified multiple nonsense mutations in a key L. monocytogenes virulence gene (inlA) leading to the production of a truncated and secreted (rather than cell wall-anchored) gene product.  L. monocytogenes strains carrying these mutations are not only associated with reduced invasiveness in human intestinal epithelial cells but also represent a significant proportion (ca. 30%) of L. monocytogenes isolated from food samples (Nightingale et al., 2005; Appl. Environ. Microbiol.).

The specific aims of this project include, (i) determine if nonsense mutations in inlA are causally associated with virulence attenuation, (ii) develop rapid genetic and phenotypic assays to detect L. monocytogenes strains with reduced virulence and describe the distribution of these strains among different source populations along the food chain and (iii) develop appropriate dose response models and a revised risk assessment which incorporates knowledge regarding strain-specific virulence characteristics.

EDUCATION:
Post-Doctoral Research,Research Associate, Cornell University

Research focus: Molecular subtyping, molecular epidemiology and molecular evolution of foodborne, waterborne, zoonotic, and other bacterial pathogens.

Ph.D. 2005. Food Science with minors in Epidemiology and Microbiology, Cornell University

M.S. 2001. Food Science with a concentration in Food Microbiology, Kansas State University

B.S. 1999. Agriculture with a major in Animal Sciences and Industry, Kansas State University

Link to supplemental data files for manuscripts