David A. Welsh, MD

Howard A. Buechner Professor of Medicine

Associate Professor of Clinical Medicine

Associate Professor of Microbiology, Immunology and Parasitology

Section of Pulmonary/Critical Care & Allergy/Immunology

1901 Perdido Street,
MEB, Suite 3205

New Orleans, LA  70112

504.568.4634 [voice]

504.568.4295 [fax]


Microbial Genomics Resource Group 



BA - Brandeis University, Waltham, MA
MD - University of Washington School of Medicine, Seattle, WA


Dr. Welsh received training in Internal Medicine at Vanderbilt University Medical Center before completing a fellowship in Pulmonary and Critical Care at LSU.  He oversees the HIV Chest Clinic and provides inpatient clinical care at LSU affiliated facilities.

Clinical Interests

HIV-Associated Lung Disorders

Lung Health during Incarceration

Research Interests

Resident Microbial Communities and Human Health & Aging

Resident Microbial Communities and Lung Host Defense

Inflamm-aging and Immunosenescence

Assessment of Biological Age

Human Immunodeficiency Virus (HIV)

Maladaptive Health Behaviors (Alcohol Use Disorders)

Selected Publications

Samuelson DR, Burnham E, Maffei VJ, Vandizier RW, Blanchard EE, Shellito JE, Luo M, Taylor CM, Welsh DA.  The respiratory tract microbial biogeography in alcohol use disorder.  Am J Physiol  Lung Cell Mol Physiol.  2017.  In Press.

Samuelson DR, Shellito JE, Maffei VJ, Tague ED, Campagna SR, Blanchard EE, Luo M, Taylor CM, Ronis MJJ, Molina PE, Welsh DA.  Alcohol-associated intestinal dysbiosis impairs pulmonary host defense against Klebsiella pneumoniae. PLoS Pathogens. 2017; 13(6):e1006426. 

Byerley LO, Samuelson D, Blanchard E 4th, Luo M, Lorenzen BN, Banks S, Ponder MA, Welsh DA, Taylor CM. Changes in the gut microbial communities following addition of walnuts to the diet. The Journal of nutritional biochemistry. 2017; 48:94-102.

Maffei VJ, Kim S, Blanchard E 4th, Luo M, Jazwinski SM, Taylor CM, Welsh DA.  Biological Aging and the Human Gut Microbiota. The journals of gerontology. Series A, Biological sciences and medical sciences. 2017; 

Ruan S, Cai Y, Ramsay AJ, Welsh DA, Norris K, Shellito JE. B cell and antibody responses in mice induced by a putative cell surface peptidase of Pneumocystis murina protect against experimental infection. Vaccine. 2017; 35(4):672-679.

Goldsmith F, Guice J, Page R, Welsh DA, Taylor CM, Blanchard EE, Luo M, Raggio AM, Stout RW, Carvajal-Aldaz D, Gaither A, Pelkman C, Ye J, Martin RJ, Geaghan J, Durham HA, Coulon D, Keenan MJ. Obese ZDF rats fermented resistant starch with effects on gut microbiota but no reduction in abdominal fat. Molecular nutrition & food research. 2017; 61(1). 

Jolley SE, Alkhafaf Q, Hough C, Welsh DA.  Presence of an alcohol use disorder is associated with greater pneumonia severity in hospitalized HIV infected patients.  Lung. 2016; 194(5):755-62.

DR Samuelson, TP Charles, NM de la Rua, CM Taylor, EE Blanchard, M Luo, JE Shellito, DA Welsh.  Analysis of the intestinal microbial community and inferred functional capacities during the host response to Pneumocystis pneumonia.  Exp Lung Res.  2016 Dec 7:1-15.

de la Rua NM, Samuelson DR, Charles TP, Welsh DA, Shellito JE. CD4(+) T-Cell-Independent Secondary Immune Responses to Pneumocystis Pneumonia.  Frontiers in immunology. 2016; 7:178.

Samuelson DR, de la Rua NM, Charles TP, Ruan S, Taylor CM, Blanchard EE, Luo M, Ramsay AJ, Shellito JE, Welsh DA. Oral Immunization of Mice with Live Pneumocystis murina Protects against Pneumocystis Pneumonia. J Immunol. 2016 Mar 15;196(6):2655-65.

Katz PS, Siggins RW, Porretta C, Armstrong ML, Zea AH, Mercante DE, Parsons C, Veazey RS, Bagby GJ, Nelson S, Molina PE, Welsh DA. Chronic alcohol increases CD8+ T-cell immunosenescence in simian immunodeficiency virus-infected rhesus macaques. Alcohol. 2015 Dec;49(8):759-65.

Stanko KE, Cherry KE, Ryker KS, Mughal F, Marks LD, et al. Looking for the Silver Lining: Benefit Finding After Hurricanes Katrina and Rita in Middle-Aged, Older, and Oldest-Old Adults. Current Psychology. 2015 August 15.

Veazey RS, Amedee A, Wang X, Bernice Kaack M, Porretta C, Dufour J, Welsh D, Happel K, Pahar B, Molina PE, Nelson S, Bagby GJ. Chronic Binge Alcohol Administration Increases Intestinal T-Cell Proliferation and Turnover in Rhesus Macaques. Alcohol Clin Exp Res. 2015 Aug;39(8):1373-9. 

Bruce-Keller AJ, Salbaum JM, Luo M, Blanchard E 4th, Taylor CM, Welsh DA, Berthoud HR. Obese-type gut microbiota induce neurobehavioral changes in the absence of obesity. Biol Psychiatry. 2015 Apr 1;77(7):607-15.

Kim S, Welsh DA, Myers L, Cherry KE, Wyckoff J, Jazwinski SM. Non-coding genomic regions possessing enhancer and silencer potential are associated with healthy aging and exceptional survival. Oncotarget. 2015 Feb 28;6(6):3600-12.

Samuelson DR, Welsh DA, Shellito JE. Regulation of lung immunity and host defense by the intestinal microbiota. Front Microbiol. 2015 Oct 7;6:1085.

NCBI Bibliography