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  1. Science & Research (NCTR)

Steven Foley Ph.D.

Director, SBRBPAS Expert — Division of Microbiology

Headshot of Dr. Steve Foley

Steven Foley, Ph.D.
(870) 543-7121
NCTRResearch@fda.hhs.gov  

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 About  |  Publications  |  Lab Members

Background

Dr. Steven Foley is a senior biological research and biological product assessment service (SBRBPAS) expert and director of the Division of Microbiology at FDA’s National Center for Toxicological Research (NCTR). Dr. Foley earned a Bachelor of Science degree in zoology and a Ph.D. in cellular and molecular biology/infectious diseases from North Dakota State University in Fargo. The focus of his research was on the expression and purification of the increased serum survival (Iss) protein, which was identified as an important virulence factor for avian pathogenic Escherichia coli, and the development and characterization of monoclonal antibodies towards Iss. He then completed a postdoctoral fellowship with FDA’s Center for Veterinary Medicine, where the focus of his research was on developing methods for source tracking of Salmonella from food-animal species.

Following his postdoctoral fellowship, Dr. Foley served as an assistant professor at the University of Central Arkansas (UCA) where he taught courses in biology and microbiology and conducted research related to antimicrobial resistance in Salmonella and E. coli. During his time at UCA, Dr. Foley also served as a science advisor for FDA’s Office of Regulatory Affairs, where he provided technical advice on research needs and methodologies. He continued as a science advisor after accepting a position as an associate research scientist with the National Farm Medicine Center at the Marshfield Clinic Research Foundation (MCRF) where he led a research program focused on antimicrobial resistance and virulence of foodborne and zoonotic pathogens.

In 2009, Dr. Foley joined NCTR and his direct research team has been focused on the fields of zoonotic diseases, food safety, and the microbiology of FDA-regulated products. Dr. Foley has completed the Leadership Arkansas program and the Leadership in a Democratic Society program through the Federal Executive Institute and has served on a variety of FDA-wide and interagency committees and workgroups. He is also an adjunct professor at the University of Arkansas and has mentored multiple students from the University of Arkansas at Pine Bluff. In 2018, Dr. Foley was selected as a member in the Arkansas Research Alliance Academy of Scholars and Fellows.

 

Research Interests

Dr. Foley’s multifaceted research program addresses FDA research needs in the areas of antimicrobial resistance and virulence in foodborne pathogens and the microbial characterization of FDA-regulated products. Plasmids that are present in Salmonella enterica and other enteric pathogens often contain multiple genes that can encode for antimicrobial resistance, increased colonization, and/or overall virulence. A long-term goal of Dr. Foley’s research is to better understand the role of plasmids in increased virulence among Salmonella enterica. In his previous studies, DNA sequencing of plasmids identified factors that are likely important for increased virulence and antimicrobial resistance in Salmonella. For example, his team’s research has demonstrated the contribution of plasmid-encoded VirB/D4 Type 4 secretion systems to increased invasion and survival in model systems. Several other plasmid types also appear to encode potential virulence factors, often along with antimicrobial-resistance genes, which is why Dr. Foley’s team aims to further clarify their roles in virulence and whether there is a co-selection of increased virulence and resistance. To these ends, Dr. Foley led a project to develop genetic approaches and methodologies to more efficiently cure plasmids and inactivate plasmid-associated genes to facilitate a functional analysis of their roles in bacterial physiology. Additionally, the team developed Salmonella virulence factor and resistance plasmid transfer gene databases (https://virulence.fda.gov) to efficiently identify and compare genes identified in whole genome sequencing (WGS) efforts. WGS can be a tool to better understand Salmonella diversity and the evolution of virulence.

Dr. Foley also seeks to better understand the factors that impact plasmid-transfer efficiency. Preliminary studies have shown that differential exposure to certain antimicrobial agents can impact the efficiency of plasmid transfer and the team’s ongoing research builds upon these earlier studies to evaluate a larger diversity of plasmids associated with Salmonella to identify their impact on pathogenicity (both looking at the pathogen and host sides of the equation) and to refine the understanding of the role of antimicrobial exposure that may influence plasmid transfer among Salmonella and other enteric organisms. The research team is working to combine the bioinformatics approaches and laboratory methods to better understand the dissemination and diversity of plasmids.

 

Professional Societies/National and International Groups

American Society for Microbiology
Member
1997 – Present

Arkansas Association for Food Protection
Member
2009 – Present

International Association for Food Protection
Member
2005 – Present

MidSouth Computational Biology & Bioinformatics Society
Member
2016 – Present

Conference Committee Chair
2019 – 2021

 

Selected Publications

Genotypic Analyses of IncHI2 Plasmids from Enteric Bacteria.
Algarni S., Gudeta D.D., Han J., Nayak R., and Foley S.L. 
Nature Sci Reports. 2024, 14: 9802. 

Infection Biology of Salmonella enterica. 
Han J., Aljahdali N., Zhao S., Tang H., Harbottle H., Hoffmann M., Frye J.G., and Foley S.L. 
Eco Sal Plus. 2024, 12:esp00012023.

Versatile Allelic Replacement and Self-Excising Integrative Vectors for Plasmid Genome Mutation and Complementation.
Gudeta D.D. and Foley S.L. 
Microbiol Spectrum. 2023, 11:e03387-23. 

In Silico Analyses of Diversity, and Dissemination of Antimicrobial Resistance Genes and Mobile Genetics Elements, for Plasmids of Enteric Pathogens.
Algarni S., Han J., Gudeta D.D., Khajanchi B.K., Ricke S.C., Kwon Y., Rhoads D.D., and Foley S.L. 
Front. Microbiol. 2023, 13:1095128. 

Investigation of Microorganisms in Cannabis after Heating in a Commercial Vaporizer.
Sopovski D.S., Han J., Stevens-Riley M., Wang Q., Erickson B.D., Oktem B., Vanlandingham M., Taylor C.M., and Foley S.L. 
Front Cell Infect Microbiol. 2023, 12: 1051272. 

The Dynamics of the Antimicrobial Resistance Mobilome of Salmonella enterica and Related Enteric Bacteria.
Algarni S., Ricke S.C., Foley S.L., and Han J. 
Front Microbiol. 2022, 13:859854. doi: 10.3389/fmicb.2022.859854.

Incompatibility Group I1 (IncI1) Plasmids: A Review of their Genetics, Biology, and Public Health Relevance.
Foley S.L., Kaldhone P.R., Ricke S.C., and Han J.
Microbiol Mol Biol Rev. 2021, 85:e00031-20.

Current Knowledge and Perspectives of Potential Impacts of Salmonella enterica on the Profile of the Gut Microbiota.
Aljahdali N.H., Sanad Y.M., Han J., and Foley S.L.
BMC Microbiol. 2020, 20(1):353.

Genotypic and Phenotypic Characterization of Incompatibility Group FIB Positive Salmonella enterica serovar Typhimurium Isolates from Food Animal Sources.
Aljahdali N.H., Khajanchi B.K., Weston K., Deck J., Cox J., Singh R., Gilbert J., Sanad Y.M., Han J., Nayak R., and Foley S.L.
Genes. 2020, 11(11):1307.

The Gut Microbiome and Xenobiotics: Identifying Knowledge Gaps.
Sutherland V.L., McQueen C.A., Mendrick D., Gulezian D., Cerniglia C., Foley S., Forry S., Khare S., Liang X., Manautou J.E., Tweedie D., Young H., Aleksenkyo A., Burns F., Dietert R., Karberg K., Wilson A., and Chen C.
Tox Sci. 2020, 176: 1-10.

Evaluation of the Genetics and Functionality of Plasmids in Incompatibility Group I1-Positive Salmonella enterica.
Kaldhone P., Han J., Deck J., Khajanchi B., Nayak R., Foley S., and Ricke S.
Foodborne Path. Dis. 2018, 15: 168-176.

Impact of Co-Carriage of IncA/C Plasmids with Additional Plasmids on the Transfer of Antimicrobial Resistance in Salmonella enterica Isolates.
Han J., Pendleton S., Deck J., Singh R., Gilbert J., Johnson T., Sanad Y., Nayak R., and Foley S.
Int J Food Microbiol. 2018, 271:77-84.

Comparative Genomic Analysis and Characterization of Incompatibility Group FIB Plasmid Encoded Virulence Factors of Salmonella enterica Isolated from Food Sources.
Khajanchi B., Hassan N., Choi S., Han J., Zhao S., Colwell R., Cerniglia C., and Foley S.
BMC Genomics. 2017, 18:570.

Bacterial Populations Associated with Smokeless Tobacco Products.
Han J., Sanad Y., Deck J., Sutherland J., Li Z., Walters M., Duran N., Holman M., and Foley S.
Appl Enivron Microbiol. 2016, 82(20):6273-6283.

Evaluation of Virulence and Antimicrobial Resistance in Salmonella enterica Serovar Enteritidis Isolates from Humans and Chicken- and Egg-Associated Sources.
Han J., Gokulan K., Barnette D., Khare S., Rooney A., Deck J., Nayak R., Stefanova R., Hart M., and Foley S.
Foodborne Path Dis. 2013, 10(12):1008-1015.

Salmonella Pathogenicity and Host Adaptation in Chicken-Associated Serovars.
Foley S., Johnson T., Ricke S., Nayak R., and Danzeisen J.
Microbiol Mol Biol Rev. 2013, 77(4):582-607.

Impact of Plasmids, Including Those Encoding VirB4/D4 Type IV Secretion Systems on Salmonella enterica Serovar Heidelberg Virulence in Macrophages and Epithelial Cells.
Gokulan K., Han J., Khare S., Rooney A., Lynne A., and Foley S. 
PLOS ONE. 2013, 8(10):e77866.

DNA Sequence Analysis of Multidrug Resistance Encoding Plasmids from Salmonella enterica Serotype Heidelberg Isolates.
Han J., Lynne A., David D., Tang H., Xu J., Nayak R., Kaldhone P., Logue C., and Foley S. 
PLOS ONE. 2012, 7(12):e51160.

Population Dynamics of Salmonella enterica Serotypes in Commercial Egg and Poultry Production.
Foley S., Nayak R., Hanning I., Johnson T., Han J., and Ricke S.
Appl Environ Microbiol. 2011, 77(13):4273-4279.

Comparison of Salmonella enterica Serovar Heidelberg Isolated from Human Patients with Those from Animal and Food Sources. 
Han J., David D., Deck J., Lynne A., Kaldhone P., Nayak R., Stefanova R., and Foley S.
J Clin Micro. 2011, 49(3):1130-33.

 

Lab Members

Contact information for all lab members:
(870) 543-7121
NCTRResearch@fda.hhs.gov

Dereje Gudeta, Ph.D.
Research Microbiologist

Jing Han, Ph.D.
Research Microbiologist

Danielle Sopovski, M.S.
Support Scientist

Contact Information
Steven Foley
(870) 543-7121
Expertise
Expertise
Approach
Domain
Technology & Discipline
Toxicology
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