Andreas Baumler

image of Andreas Baumler



Medical Microbiology and Immunology

Offices and Labs

GBSF 5513
530 754 7225

Profile Introduction

Molecular Mechanisms of Salmonella Interaction with the Intestinal Mucosa



1992 Dr. rer. nat (PhD) Microbial physiology Eberhard-Karls Universität Tübingen, Germnay

Research Contribution

Research Interests

Interaction of Salmonella with the host and its microbiota

The intestine is host to a diverse bacterial community whose structure, at the phylum level, is maintained through unknown mechanisms. Acute inflammation triggered by S. typhimurium is accompanied by changes in the bacterial community structure marked by an outgrowth of the pathogen. Our studies show how S. typhimurium can use specific metabolic traits to harness benefit from the host response and edge out the beneficial bacterial species that dominate in the healthy gut. The elucidation of how S. Typhimurium alters the bacterial community structure during gastroenteritis is beginning to provide insights into mechanisms that dictate the balance between the host and its microbiota.

Pathogenesis of typhoid fever and gastroenteritis

The genus Salmonella contains a group of closely related organisms that are pathogenic for humans and other vertebrates. The human disease manifestations caused most frequently by Salmonella serotypes worldwide are typhoid fever and gastroenteritis. One focus of my lab is to understand why typhoid fever and gastroenteritis differ in the host response elicited at the site where both infections originate, the intestinal mucosa. Gastroenteritis caused by non-typhoidal Salmonella serotypes (e.g. S. typhimurium) is a localized infection with short incubation period (<24 hours on average). In contrast, typhoid fever caused by the human-adapted S. typhi is a severe systemic infection with a two-week incubation period. The host restricts dissemination of S. typhimurium by mounting acute inflammatory responses characterized by the recruitment of neutrophils. However, S. typhi can bypass these defenses and cause an invasive bloodstream infection. Our work on virulence mechanisms of S. typhi suggests that expression of a capsular polysaccharide and altered virulence gene expression act in concert to evade detection by the innate immune system, thereby enabling the pathogen to penetrate defenses that prevent bacterial dissemination. Thus, the presence of certain virulence traits, such as a capsule or altered virulence gene regulation, can drastically attenuate host responses in the intestinal mucosa and alter the clinical presentation associated with otherwise closely related bacterial pathogens.


2000. Junior Investigator Award, Texas A&M Univ. SHSC, College of Medicine
2010. Fellow, American Academy of Microbiology
2013. UC Davis School of Medicine Research Award, University of California at Davis

Department and Center Affiliations

Medical Microbiology and Immunology

CBS Grad Group Affiliations

Biochemistry, Molecular, Cellular and Developmental Biology

Specialties / Focus

Biochemistry, Molecular, Cellular and Developmental Biology
  • Molecular Microbiology

Graduate Groups not Housed in CBS

Graduate Group in Immunology
Comparative Pathology


MMI 200D Mechanisms for microbial interactions with hosts (Winter)
MMI 280 The endogenous microbiota in health and disease (Spring)


3/17/2015 11:51:46 AM
  • 2008. M. Raffatellu, R.L .Santos, D. Verhoeven, M.D. George, R.P. Wilson, S.E. Winter, I. Godinez, S. Sankaran, T.A. Paixao, M.A. Gordon, J.K. Kolls, S. Dandekar, and A.J. Bäumler. Simian immunodeficiency virus–induced mucosal IL–17 deficiency promotes Salmonella dissemination from the gut. Nature Medicine. 14:421-428.

  • 2008. Tsolis, R.M., G.M. Young, J.V. Solnick and A.J. Bäumler. From bench to bedside: stealth of enteroinvasive pathogens. Nature Rev. Microbiol. 6:883-892.

  • 2009. Tükel, Ç., R.P. Wilson, M. Pezeshki, B.A. Chromy and A.J. Bäumler. Responses to amyloids of microbial and host origin are mediated through Toll-like receptor 2. Cell Host Microbe. 6:45-53

  • 2009. Raffatellu, M., M.D. George, Y. Akiyama, M.J. Hornsby, S.-P. Nuccio, T.A. Paixao, B.P. Butler, H. Chu, R.L. Santos, T. Berger, T.W. Mak, R.M. Tsolis, C.L. Bevins, J.V. Solnick, S. Dandekar and A.J. Bäumler. Lipocalin-2 resistance confers an advantage to Salmonella enterica serotype Typhimurium for growth and survival in the inflamed intestine. Cell Host Microbe. 5:476-486.

  • 2010. Winter, S.E., M.G. Winter, I. Godinez, H.-J. Yang, H. Rüssmann, H.L. Andrews-Polymenis, A.J. Bäumler. A rapid change in virulence gene expression during the transition from the intestinal lumen into tissue promotes systemic dissemination of Salmonella. PLOS Pathogens. 6: e1001060.

  • 2010. Winter S.E., P. Thiennimitr, M.G. Winter, B. Butler, D.L. Huseby, R.W. Crawford, J.M. Russell, C.L. Bevins, L.G. Adams, R.M. Tsolis, J.R. Roth and A.J. Bäumler. Gut inflammation provides a respiratory electron acceptor for Salmonella. Nature. 467:426-429.

  • 2010. Winter, S.E., A.M. Keestra, R.M. Tsolis and A.J. Bäumler. The blessings and curses of intestinal inflammation. Cell Host & Microbe 8:36-43.

  • 2011. Fookes, M., G.N. Schroeder, G. Langridge, C.J. Blondel, C. Mammina, G.S. Vernikos, K.S. Robinson, N.K. Petty, R.A. Kingsley, A.J. Bäumler, S.-P. Nuccio, I. Contreras, C.A. Santiviago, D. Maskell, P. Barrow, T. Humphrey, A. Nastasi, M. Roberts, G. Frankel, J. Parkhill, G. Dougan, N.R. Thomson. Salmonella bongori provides insights into the evolution of the salmonellae. PLOS Pathogens. 7: e1002191.

  • 2011. Thiennimitr, P., S.E. Winter, M.G. Winter, M.N. Xavier, V. Tolstikov, D.L. Huseby, T. Sterzenbach, R.M. Tsolis, J.R. Roth, A.J. Bäumler. Intestinal inflammation allows Salmonella to utilize ethanolamine to compete with the microbiota. Proc. Natl. Acad. Sci. USA. 108:17480-17485.

  • 2011. Keestra, A.M., M.G. Winter, D. Klein-Douwel, M.N. Xavier, S.E. Winter, A. Kim, R.M. Tsolis and A.J. Bäumler. A Salmonella virulence factor activates the Nod1/Nod2 Signaling Pathway. mBIO. 2:e00266-11.

  • 2011. Keestra, A.M. and A.J. Bäumler. Host defenses trigger Salmonella’s arsenal. Cell Host & Microbe. 9:167-168.

  • 2012. Lee, S.-J., J.B McLachlan, J.R. Kurtz, D. Fan, S.E. Winter, A.J. Bäumler, M.K. Jenkins, and S.J. McSorley. Temporal expression of bacterial proteins instructs host CD4 T cell expansion and Th17 development. PLoS Pathogens. 8(1):e1002499. (PMID: 22275869)

  • 2012. Lopez, C.A., S.E. Winter, F. Rivera-Chávez, M.N. Xavier, V. Poon, S.-P. Nuccio, R.M. Tsolis and A.J. Bäumler. Phage-mediated acquisition of a type III secreted effector protein boosts growth of Salmonella by nitrate respiration. mBIO. 3:e00143-12. (PMID: 22691391)

  • 2012. Chu, H., M. Pazgier, G. Jung, S.-P. Nuccio, P.A. Castillo, M.F. de Jong, M.G. Winter, S.E. Winter, J. Wehkamp, B. Shen, N.H. Salzman, M.A. Underwood, R.M. Tsolis, G.M. Young, W. Lu, R.I. Lehrer, A.J. Bäumler, and C.L. Bevins. Human α-defensin 6 promotes mucosal innate immunity through self-assembled peptide nanonets. Science. 337:477-481. (PMID: 22722251)

  • 2012. Crawford, R.W., A.M. Keestra, S.E. Winter, M.N. Xavier, R.M. Tsolis, V. Tolstikov and A.J. Bäumler. Very long O-antigen chains enhance fitness during Salmonella-induced colitis by increasing bile resistance. PLOS Pathogens.  8: e1002918. (PMID: 23028318)

  • 2012. Fang, F.C. and A.J. Bäumler. A Toll gate for typhoid. Cell. 151:473-475.

  • 2013. Winter, S.E., M.G. Winter, M.N. Xavier, P. Thiennimitr, V. Poon, A.M. Keestra, R. Laughlin, G. Gomez, J. Wu, S.D. Lawhon, I. Popova, S.J. Parikh, L.G. Adams, R.M. Tsolis, V.J. Stewart and A.J. Bäumler. Host-derived nitrate boosts growth of E. coli in the inflamed gut. Science. 339:708-711.

  • 2013. Rivera-Chávez, F., S.E. Winter, C.A. Lopez, M.N. Xavier, M.G. Winter, J.M. Russell, R.C. Laughlin, S.D. Lawhon, T. Sterzenbach, C.L. Bevins, R.M. Tsolis, R. Harshey, L.G. Adams and A.J. Bäumler. Salmonella uses energy taxis to benefit from intestinal inflammation. PLOS Pathogens. 9(4): e1003267


  • 2013. Spees, A.M., T. Wangdi, C.A. Lopez, D.D. Kingsbury, M.N. Xavier, S.E. Winter, R.M. Tsolis and A.J. Bäumler. Streptomycin-induced inflammation enhances Escherichia coli gut colonization through nitrate respiration. mBIO. 4: e00430-13.

  • 2013. Xavier, M.N., M.G. Winter, A.M. Spees, K. Nguyen, V.L. Atluri, A.B. den Hartigh, T.M. A. Silva, P.A. Luciw, D.M. Monack, A.J. Bäumler, R.L. Santos, R.M. Tsolis. A PPAR-mediated increase in glucose availability sustains chronic Brucella abortus infection in alternatively activated macrophages. Cell Host & Microbe. 14:159-170.

  • 2013. Spees, A.M., C.A. Lopez, D.D. Kingsbury, S.E. Winter and A.J. Bäumler. Colonization resistance: battle of the bugs or ménage à trois with the host? PLOS Pathogens. 9: e1003730

  • 2013. Crawford, R.W., T. Wangdi, A.M. Spees, M.N. Xavier, R.M. Tsolis and A.J. Bäumler. Loss of very-long O-antigen chains optimizes capsule-mediated immune evasion by Salmonella enterica serovar Typhi. mBIO. 4: e00232-13.

  • 2013. Xavier, M.N., M.G. Winter, A.M. Spees, K. Nguyen, V.L. Atluri, T.A.M. Silva, A.J. Bäumler, W. Müller3, R.L. Santos2, R.M.Tsolis. CD4+ T cell derived IL-10 promotes Brucella abortus persistence through modulation of macrophage function during early infection. PLOS Pathogens. 9: e1003454.

  • 2013. Sterzenbach, T., K.T. Nguyen, S.-P. Nuccio, M.G. Winter, C. Vakulskas, S. Clegg, T. Romeo and A.J. Bäumler. A novel CsrA titration mechanism regulates fimbrial gene expression in Salmonella Typhimurium. EMBO J. 32:2872-2883.

  • 2013. Keestra, A.M., M.G. Winter, J.J. Auburger, S.P. Fräßle, M.N. Xavier, S.E. Winter, A. Kim, V. Poon, M.M. Ravesloot, J. Waldenmaier, R.M. Tsolis, R.A. Eigenheer and A.J. Bäumler. Manipulation of small Rho GTPases is a pathogen-induced process detected by Nod1. Nature. 496:233-237.

  • 2014. Laughlin, R.C., L.A. Knodler, R. Barhoumi, H.R. Payne, J. Wu, G. Gomez, R. Pugh, S.D. Lawhon, A.J. Bäumler, O. Steele-Mortimer, L.G. Adams. Spatial segregation of virulence gene expression during acute enteric infection with Salmonella enterica serovar Typhimurium. mBIO. 5: e00946-13.

  • 2014. Nuccio, S.-P. and A.J. Bäumler. Comparative analysis of Salmonella genomes identifies a metabolic network for escalating growth in the inflamed gut. mBIO. 5: e00929-14.


  • 2014. Hirao, L.A, I. Grishina, O. Bourry, W.K. Hu, M. Somrit, S. Sankaran-Walters, C.A. Gaulke, A.N. Fenton, J.A. Li, R.W. Crawford, F. Chuang, R. Tarara, M. Marco, A.J. Bäumler, H. Cheng and S. Dandekar. Early Mucosal Sensing of SIV Infection by Paneth Cells Induces IL-1b Production and Initiates Gut Epithelial Disruption. PLOS Pathogens. 10: e1004311.

  • 2014. O’Donnell, H., O. Pham, L.-X. Li, S.-P. Nuccio, D. Monack, A.J. Bäumler, and S.J. McSorley. Innate bactericidal capacity of Th1 cells is tuned by TLR and inflammasome signaling. Immunity. 40: 213–224.

  • 2014. Lokken, K.L., R.M. Tsolis and A.J. Bäumler. Hypoferremia of infection: a double-edged sword? Nature Medicine. 20:335-337.

  • 2014. Wangdi, T, C.-Y. Lee, A.M. Spees, C. Yu, D.D. Kingsbury, S.E. Winter, C.J. Hastey, R.P. Wilson, V. Heinrich* and A.J. Bäumler*. The Vi capsular polysaccharide enables Salmonella enterica serovar Typhi to evade microbe-guided neutrophil chemotaxis. PLOS Pathogens. 10: e1004306.

  • 2014. Winter, S.E., M.G. Winter, V. Poon, A.M. Keestra, T. Sterzenbach, F. Faber, and A.J. Bäumler. Salmonella enterica serovar Typhi conceals the invasion-associated type three secretion system from the innate immune system by gene regulation. PLOS Pathogens. 10: e1004207.

  • 2014. Hirao, L.A, I. Grishina, O. Bourry, W.K. Hu, M. Somrit, S. Sankaran-Walters, C.A. Gaulke, A.N. Fenton, J.A. Li, R.W. Crawford, F. Chuang, R. Tarara, M. Marco, A.J. Bäumler, H. Cheng and S. Dandekar. Early Mucosal Sensing of SIV Infection by Paneth Cells Induces IL-1b Production and Initiates Gut Epithelial Disruption. PLOS Pathogens. 10: e1004311.

  • 2014. Lopez, C.A., D.D. Kingsbury, E.M. Velazquez and A.J. Bäumler. Collateral Damage: Microbiota-derived Metabolites and Immune Function in the Antibiotic Era. Cell Host & Microbe. 16(2):156-163.