Youngbeom Ahn Ph.D.

Microbiologist — Division of Microbiology

Youngbeom Ahn, Ph.D.
(870) 543-7121
NCTRResearch@fda.hhs.gov

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Background

Dr. Ahn joined the Division of Microbiology at FDA’s Center for Toxicological Research (NCTR) as a staff fellow in 2009 where his research interests have focused on projects of FDA regulatory science including antimicrobial residues in foods and the safety of pharmaceutical products as related to microbial contamination. In cooperation with FDA’s Center for Veterinary Medicine (CVM), Dr. Ahn developed a project to assess the impact of antimicrobial residues on the human gastrointestinal tract microbiota. He also initiated a collaboration with FDA’s Center for Drug Evaluation and Research (CDER) to develop a CDER-funded project that explored strategies for resuscitation and enrichment of Burkholderia cepacia complex (BCC) strains in pharmaceutical products. Dr. Ahn’s research provided information on methodological questions that have concerned national regulatory authorities in in vitro testing to determine if concentrations of veterinary antimicrobial agent residues entering the human colon remain microbiologically active. His research resulted in significant data that assisted FDA and other national regulatory authorities in the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medical Products (VICH) Expert Working Group organized by CVM to evaluate the VICH GL36 guideline on the human safety of veterinary antimicrobial drugs. For his scientific contributions, the incumbent was awarded the FDA/NCTR Outstanding Junior Investigator in 2013. He received the NCTR Special Act Award in 2017 for outstanding research and regulatory impact on providing data to FDA/CVM on the effect of short- and long-term exposure to residual levels of tetracycline in food on the intestinal microbiome.

Research Interests

The laboratory of microbiome and host interactions within the division has been established to investigate the effects of food-contaminant residues on the gastrointestinal-tract microbiota. Dr. Ahn’s current studies are focused on the impact of antibiotics on the human gastrointestinal-tract microbiota. Most studies on drug binding to fecal contents have used therapeutic human doses, rather than levels below or slightly above the minimal risk level allowed in edible tissues. The research project answered one of the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products’ most pivotal methodological questions of whether residues entering the human colon remain biologically active by comparing the fecal binding of selected antibiotics concentrations with various incubation conditions using physiochemical, analytical chemistry, microbiological, and molecular methods.

Dr. Ahn is also collaborating with CDER on a project to explore strategies for resuscitation and enrichment of BCC strains in pharmaceutical products. The Centers for Disease Control (CDC) has requested that FDA issue a rule or policy that establishes B. cepacia as an objectionable organism in pharmaceuticals, and the United States Pharmacopeia (USP) has revisited the concept of including B. cepacia in its chapters. For USP to include this species as an organism of interest, they must have a test that can be done by nearly any microbiology laboratory using conventional technology. However, existing USP methods use enrichment in Trypticase Soy Broth, which is inadequate for all strains. The objectives of Dr. Ahn’s research are to 1) develop a resuscitative step and enrichment technique for BCC recovery and 2) develop methodology to detect BCC and its 16 related genomovars. He also looks to evaluate the use of modern molecular technologies to identify BCC.

Professional Societies/National and International Groups

American Society for Microbiology
Member
2012 — Present

Selected Publications

Loop-Mediated Isothermal Amplification (LAMP) Assay for Detecting Burkholderia cepacia Complex in Non-Sterile Pharmaceutical Products.
Daddy Gaoh S., Kweon O., Lee Y.J., LiPuma J.J., Hussong D., Marasa B., and Ahn Y.
Pathogens. 2021, 10(9):1071. doi: 10.3390/pathogens10091071.

Impact of Chronic Tetracycline Exposure on Human Intestinal Microbiota in a Continuous Flow Bioreactor Model.
Ahn Y., Jung J.Y., Kweon O., Veach B.T., Khare S., Gokulan K., Piñeiro S.A., and Cerniglia C.
Antibiotics (Basel). 2021, 10(8):886. doi: 10.3390/antibiotics10080886.

Detection of Campylobacter jejuni from Fresh Produce: Comparison of Culture- and PCR-Based Techniques, and Metagenomic Approach for Analyses of the Microbiome Before and After Enrichment.
Chon J.W., Jung J.Y., Ahn Y., Bae D., Khan S., Seo K.H., Kim H., and Sung K.
J Food Prot. 2021. doi: 10.4315/JFP-20-408. Online ahead of print.

Reductive Debromination by Sponge-Associated Anaerobic Bacteria Coupled to Carbon Isotope Fractionation.
Horna-Gray I., Lopez N., Nijenhuis I., Ahn Y., Richnow H.H., and Häggblom M.M.
International Biodeterioration & Biodegradation. 2020, 155:105093. doi: 10.1016/j.ibiod.2020.105093

A Comparison of Culture-Based, Real-Time PCR, Droplet Digital PCR and Flow Cytometric Methods for the Detection of Burkholderia cepacia Complex in Nuclease-Free Water and Antiseptics.
Ahn Y., Gibson B., Williams A., Alusta P., Buzatu D.A., Lee Y.J., LiPuma J.J., Hussong D., Marasa B., and Cerniglia C.
J Ind Microbiol Biotechnol. 2020, 47(6-7):475-484. doi: 10.1007/s10295-020-02287-3. Epub 2020 Jul 15.

Oligotrophic Media Compared with a Tryptic Soy Agar or Broth for the Recovery of Burkholderia cepacia Complex from Different Storage Temperatures and Culture Conditions.
Ahn Y., Lee U.J., Lee Y.J., LiPuma J.J., Hussong D., Marasa B., and Cerniglia C.
J Microbiol Biotechnol. 2019, 29(10):1495-1505. doi: 10.4014/jmb.1906.06024.

In vitro Test Systems to Determine Tetracycline Residue Binding to Human Feces.
Ahn Y., Jung J.Y., Veach B.T., Khare S., Gokulan K., Piñeiro S.A., and Cerniglia C.
Regul Toxicol Pharmacol. 2018, 99:105-115. doi: 10.1016/j.yrtph.2018.09.013. Epub 2018 Sep 15.

An In vitro Study to Assess the Impact of Tetracycline on the Human Intestinal Microbiome.
Jung J., Ahn Y., Khare S., Gokulan K., Piñeiro S., and Cerniglia C.
Anaerobe. 2018, 49:85-94. doi: 10.1016/j.anaerobe.2017.12.011. Epub 2017 Dec 30.

Effects of Extended Storage of Chlorhexidine Gluconate and Benzalkonium Chloride Solutions on the Viability of Burkholderia cenocepacia.
Ahn Y., Kim J., Lee Y., LiPuma J., Hussong D., Marasa B., and Cerniglia C.
J Microbiol Biotechnol. 2017, 27(12):2211-2220. doi: 10.4014/jmb.1706.06034.

Novel Reductive Dehalogenases from the Marine Sponge Associated Bacterium Desulfoluna spongiiphila.
Liu J., Lopez N., Ahn Y., Goldberg T., Bromberg Y., Kerkhof L., and Häggblom M.
Environ Microbiol Rep. 2017, 9(5):537-549. doi: 10.1111/1758-2229.12556. Epub 2017 Jul 21.

Improved High-Quality Draft Genome Sequence and Annotation of Burkholderia contaminans LMG 23361T.
Jung J., Ahn Y., Kweon O., LiPuma J., Hussong D., Marasa B., and Cerniglia C.
Genome Announc. 2017, 5(16). pii: e00245-17. doi: 10.1128/genomeA.00245-17.

Intrinsic Resistance of Burkholderia cepacia Complex to Benzalkonium Chloride.
Ahn Y., Kim J., Kweon O., Kim S., Jones R., Woodling K., Gamboa da Costa G., LiPuma J., Hussong D., Marasa B., and Cerniglia CE.
MBio. 2016, 7(6). pii: e01716-16. doi: 10.1128/mBio.01716-16.

Survival and Susceptibility of Burkholderia cepacia Complex in Chlorhexidine Gluconate and Benzalkonium Chloride.
Kim J., Ahn Y., LiPuma J., Hussong D., and Cerniglia C.
J Ind Microbiol Biotechnol. 2015, 42(6):905-13.

Pleiotropic and Epistatic Behavior of a Ring-Hydroxylating Oxygenase System in the Polycyclic Aromatic Hydrocarbon Metabolic Network from Mycobacterium vanbaalenii PYR-1.
Kweon O., Kim S., Kim D., Kim J., Kim H., Ahn Y., Sutherland J., and Cerniglia C.
J Bacteriol. 2014, 196(19):3503-15. doi: 10.1128/JB.01945-14. Epub 2014 Jul 28.

Evaluation of Liquid and Solid Culture Media for the Recovery and Enrichment of Burkholderia cenocepacia from Distilled Water.
Ahn Y., Kim J., Ahn H., Lee Y., LiPuma J., Hussong D., and Cerniglia C.
J Ind Microbiol Biotechnol. 2014, 41(7):1109-18.

Influence of Sterilized Human Fecal Extract on the Sensitivity of Salmonella enterica ATCC 13076 and Listeria monocytogenes ATCC 15313 to Enrofloxacin.
Ahn Y., Stuckey R., Sung K., Rafii F., and Cerniglia C.
Antibiotics (Basel). 2013, 2(4):485-99. doi: 10.3390/antibiotics2040485.

In vitro Analysis of the Impact of Enrofloxacin Residues on the Human Intestinal Microbiota Using H-NMR Spectroscopy.
Ahn Y., Jung J., Chung Y., Chae M., Jeon C., and Cerniglia C.
J Mol Microbiol Biotechnol. 2012, 22(5):317-25.

Effect of Sterilized Human Fecal Extract on the Sensitivity of Escherichia coli ATCC 25922 to Enrofloxacin.
Ahn Y., Sung K., Rafii F., and Cerniglia C.
J Antibiot (Tokyo). 2012, 65(4):179-84.

In vitro Enrofloxacin Binding in Human Fecal Slurries.
Ahn Y., Linder S., Veach B., Steve Yan S., Haydée Fernández A., Pineiro S., and Cerniglia C.
Regul Toxicol Pharmacol. 2012, 62(1):74-84.

Lab Members

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

Soumana Daddy Gaoh, Ph.D.
Postdoctoral Fellow

Contact Information: Youngbeom Ahn; (870) 543-7121