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Research Profile PD Dr. Oliver Bader

  • Management AG Mycology
  • IT coordination of the institute
  • Microbiological diagnostic mass spectrometry laboratory
  • Curator of the international MLST database for Candida glabrata (pubmlst.org/).
  • Deputy ring test leader Candida serology(Instand e.V.)

Contact: +49 551 39 65403; obader(at)gwdg.de

My team and I are mainly involved in various aspects of epidemiology, diagnostics and pathogenesis of clinically relevant fungal infections in humans [complete list of publications], but also work with various bacterial pathogens depending on the research question. 

Depending on capacity, we are open to laboratory rotations as well as bachelor's and master's theses from molecular biology-oriented courses at the University of Göttingen, and we also offer places with a high practical laboratory component for medical doctorates.

Work on Aspergillus fumigatus

In the human pathogenic mold Aspergillus fumigatus, acquired resistance to clinically used azole drugs is an increasing clinical problem in critically ill patients worldwide. Much of the resistance is due to reduced affinity of the target enzyme Cyp51A to azole drugs. In addition to the classic cyp51A mutationsat positions G54 and M220, which can also result from long-term therapy, retrospective analyses have shown that pandemic alleles that spread in the environment have also occurred since the early 2000s. In addition to mutations in the protein-coding sequence, these also exhibit changes in the promoter region, which result in increased expression of cyp51A. It has been postulated that such changes are induced by exposure to azole-based fungicides used in agriculture.

Already in early studies for the German-speaking region, we were able to show that these strains occur in the environment as well as in patients, and also demonstrated for the first time the occurrence of the different spreading promoter variants (TR34, TR46) in Germany. Meanwhile, many other studies worldwide, to which we have also contributed in collaborations with partners in Thailand and East Africa, show that these resistance alleles are spreading globally. Unexpectedly, our work also revealed that alleles with alterations at G54 and M220 can also be found in the environment. Whether such resistant strains originated in the hospital setting and how they can be propagated in the environment is currently unclear.

Aspergillus fumigatus. Left: A. fumigatus in culture on agar, right: light microscopy of a conidiophor in lactophenol blue stain [Photos: Agnieszka Goretzki].

In addition to epidemiology, current work is also repeatedly concerned with the diagnostics of such resistances. In the past, this was mainly the development of resistance and PCR detection of specific mutations. In view of the introduction of new high-throughput sequencing technologies in routine microbiological diagnostics, we are currently focusing on the systematic evaluation of mutations (SNPs, allelic variants) in resistance genes (cooperation with Dr. Christoph Sasse), in order to make these evaluable for sequence analysis.

Selected Publications:

Bader O (Nov 2021) Phylogenetic Distribution of csp1 Types in Aspergillus fumigatus and Their Correlates to Azole Antifungal Drug Resistance. Microbiol Spectr. 17:e0121421. doi: 10.1128/Spectrum.01214-21.[Pubmed]

EA Idelevich EA, Groß U, Becker K, and Bader O (May 2018). Comparative evaluation of different gradient diffusion tests for detection of azole resistance in Aspergillus fumigatus .Diagn Microbiol Infect Dis 91(1):52-54. doi:10.1016/j.diagmicrobio.2018.01.003.[Pubmed]

Dudakova A, Spiess B, Tangwattanachuleeporn M, Sasse C, Buchheidt D, Weig M, Groß U, and Bader O (Oct 2017). Molecular tools for the detection and deduction of Aspergillus azole resistance phenotypes. Clinical Microbiology Reviews 50(4):1065-1091. doi: 10.1128/CMR.00095-16.[Pubmed.]

Tangwattanachuleeporn M, Minarin N, Saichan S, Sermsri P, Mitkornburee R, Groß U, Chindamporn A, and Bader O (Jun 2017). Prevalence of azole resistant Aspergillus fumigatus in the environment of Thailand. Med Mycol. 55(4):429-435. doi: 10.1093/mmy/myw090.[Pubmed]

Bader O, Tünnermann J, Dudakova A, Tangwattanachuleeporn M, Weig, and Groß U(2015). Environmental isolates of azole-resistant Aspergillus fumigatus in Germany. Antimicrob Agents Chemother 59(7):4356-9.[Pubmed.]

Work on Candida albicans

Candida albicans is a commensal yeast fungus in the gastrointestinal tract of many mammals, including humans. In healthy people, there is a well-balanced equilibrium between the immune system, the fungus and the other microorganisms of the microbiome. If this balance is upset, for example by antibacterial agents or disturbances in the immune system such as chemotherapy, the fungus can unleash its pathogenic potential and cause serious, systemic infections. Candida albicans is characterized by the fact that it can grow in many different cell morphologies, all of which play a specific role in the different niches to be colonized in the host. All forms have strongly different cellular requirements, and therefore also different transcriptome and proteome profiles.

Examples of different morphological forms of Candida albicans. (A) Yeast form, (B) Mycelium form. Left: phase contrast, right: blank phosphor P staining [Photos: Pia Sternisek].

In ongoing work, we are trying to understand how C. albicans manages to suppress mycelial growth associated with the expression of virulence properties during the commensal phase and possibly anchor this at the epigenetic level

Selected Publications:

Mühlhausen S, Schmitt HD, Plessmann U, Sternisek P, Perl T, Weig M, Urlaub H, Bader O, and Kollmar M (Dec 2021) The Candida albicans CUG codon is translated as unambiguously as every other codon. BMC Biol 19, 258. doi: 10.1186/s12915-021-01197-9.[Pubmed]

Moyes DL, Wilson D, Richardson JP, Mogavero S, Tang SX, Wernecke J, Höfs S, Gratacap RL, Robbins J, Runglall M, Murciano C, Blagojevic M, Thavaraj S, Förster TM, Hebecker B, Kasper L, Vizcay G, Iancu SI, Kichik N, Häder A, Kurzai O, Luo T, Krueger K, Kniemeyer O, Cota E, Bader O, Wheeler RT, Gutsmann T, Hube B, and Naglik JR (2016). Candidalysin is a fungal peptide toxin critical for mucosal infection. Nature 532(7597):64-8. doi: doi: 10.1038/nature17625.[Pubmed]

Work on other Candida yeasts

In addition to Candida albicans, other Candida species also occur as colonizers and pathogens in humans, including Candida parapsilosis and the phylogenetically somewhat more distant yeast Candida glabrata. In both yeasts we are mainly interested in the structure of the cell wall (cooperation with Prof. M. Weig and Prof. PW deGroot) and the resulting property to form biofilms. Candida glabrata is characterized by a large number of different potential adhesin genes, which are distributed differently in the population.

By assigning different phenotypic characteristics at the population level, we try to derive potential gains for diagnostics and therapy through subtyping. In this context, I have also been curating the international MLST database for Candida glabrata since 2016 (pubmlst.org/).

 

Population structure of C. glabrata based on MLST markers (as of 2020). Coloring analogous to [Carrete et al., 2019].

Selected Publications:

KP Wojak, G Ungermann, I Ichsan, E Gomez-Molero, K Jung, M Weig, F Nauck, D Ziebolz, Y Gräser, U Groß, B Alt-Epping, and O Bader (Jul 2021) Host age and denture wearing jointly contribute to oral colonization with intrinsically azole-resistant yeasts in the elderly. Microorganisms 9(8):1627. doi: 10.3390/microorganisms9081627. [Pubmed]

E Gómez-Molero, I De-la-Pinta, U Groß, M Weig, G Quindos, P deGroot§, and OBader§ (Jan 2021) Candida parapsilosis colony morphotype forecasts biofilm formation of clinical isolates. J Fungi (Basel) 7(1):33. doi:10.3390/jof7010033. [Pubmed]

T Gabaldón, E Gómez-Molero, and O Bader (Oct 2020) Molecular typing of Candida glabrata. Mycopathologia 185(5), 755-764. doi: 10.1007/s11046-019-00388-x.[Pubmed] 

E Gomez-Molero, JR Willis, A Dudakova, A Gacser, M Weig, U Groß, T Gabaldón, and O Bader (Aug 2020) Phenotypic variability in a coinfection with three independent C. parapsilosis lineages. Front Microbiol 11:1994. doi:10.3389/fmicb.2020.01994. [Pubmed]

L Carreté, E Ksiezopolska, E Gómez-Molero, A Angoulvant, O Bader, C Fairhead, and T Gabaldón (Feb 2019) Genome comparisons of Candida glabrata serial clinical isolates reveal patterns of genetic variation in infecting clonal populations. Front in Microbiol. 10:112 doi:10.3389/fmicb.2019.00112.[Pubmed]

§: "equal contribution"

MALDI-TOF MS & IT

In my further roles as head of the mass spectrometry laboratory and IT coordinator of the Institute of Microbiology and Virology, I combine emerging scientific methods such as MALDI-TOF mass spectrometry with my mycological interests. Using different bacterial genera (Campylobacter, Salmonella enterica, Clostridioides difficile) we have shown (in cooperation with Prof. AE Zautner) that MALDI-TOF-MS data can be used to differentiate different subtypes below the species level which correlate with different relevant phenotypes. For several other pathogenic species we are currently generating such formal typing schemes ("mass spectrometric phyloproteomics, "MSPP"). In a current project (cooperation with JunProf. AC Hauschild ) we are also working on the development of AI-based assistance systems to predict resistance phenotypes in bacteria from mass spectrometry data by linking them to local epidemiological data.

 

The MSPP scheme for C. jejunii has a similar typing depth to the genetic marker-based MLST method [Zautner et al., 2015].

Selected Publications:

M Bernhard, N Worasilchai, M Kangogo, WL Trzaska, C Bii, M Weig, U Groß, A Chindamporn, and O Bader (Apr 2021). CryptoType - Public Datasets for MALDI-TOF-MS Based Differentiation of Cryptococcusneoformans/gattii Complexes. Frontiers in Cellular and Infection Biology 11:634382. doi: 10.3389/fcimb.2021.634382.[Pubmed]

C Noll, A Nasruddin-Yekta, P Sternisek, M Weig, U Groß, AF Schilling, FT Beil, and O Bader (Dec 2020). Rapid direct detection of pathogens for diagnosis of joint infections by MALDI-TOF MS after liquid enrichment in the BacT/Alert blood culture system. PLOS ONE 15(12):e0243790. doi: 10.1371/journal.pone.0243790.[Pubmed]

O Bader (Nov 2017). Fungal species identification by MALDI-ToF mass spectrometry. Methods Mol Biol 1508:323-337. doi: 10.1007/978-1-4939-6515-1_19.[Pubmed]

AE Zautner, WO Masanta, M Weig, U Groß, and O Bader (2015) Mass Spectrometry-based PhyloProteomics (MSPP): a novel microbial typing method. Sci Rep 5:13431. doi: 10.1038/srep13431.[Pubmed]

External cooperations

Beyond our own questions, we have repeatedly supported various departments of the UMG and other universities in smaller or larger diagnostic-epidemiological projects, and performed microbiological contract research for various industrial partners.

Selected Publications:

S Taudien, W Leszczynski, T Mayer, U Loderstädt, O Bader, M Kaase, and S Scheithauer (Mar 2023) Misidentification as Pseudomonas aeruginosa in hospital water supply samples. J Hosp Infect 133:23e27. doi: 10.1016/j.jhin.2022.12.013.[Pubmed]

M Kreutz, C Kreutz, P Kanzow, T Tauböck, P Dieckmann, C Noll, O Bader, B Rohland, A Wiegand, and M Rizk (Nov 2022) Effect of bioactive and antimicrobial nanoparticles on properties and applicability of dental adhesives. Nanomaterials 12(21):3862. doi: 10.3390/nano12213862.[Pubmed].

S Dierks§, OBader§, J Schwanbeck, U Groß, M Weig, K Mese, R Lugert, W Bohne, A Hahn, N Feltgen, S Torkieh, FR Denker, P Lauermann, MW Storch, H Frickmann, and AE Zautner (May 2021) Diagnosing SARS-CoV-2 with Antigen Testing, Transcription-Mediated Amplification and Real-Time PCR. Journal of Clinical Medicine 10(11), 2404. doi: 10.3390/jcm10112404[Pubmed].

R Nißler, O Bader, M Dohmen, SG Walter, C Noll, G Selvaggio, U Groß, and S Kruss (Nov 2020). Remote near infrared detection and identification of pathogens with multiplexed nanosensors. Nature Commun 11(1): 5995. doi: 10.1038/s41467-020-19718-5.[Pubmed]

A Kauffels, G Schmalz, O Kollmar, J Slotta, M Weig, U Groß, O Bader, and D Ziebolz (2017). Oral findings and dental behavior before and after liver transplantation - a single center cross-sectional study. Int Dent J 67(4):244-251. doi: 10.1111/idj.12290 [Pubmed].

§: "equal contribution"

Members and alumni of the AG (~as of 2018)

External cooperation partners in current projects

current

  • Agnieszka Goretzki (ltd. MTA)
  • Dr. rer. nat Pia Sternisek
  • Marcel Schöne, BSc
  • Annekatrin Cordts
Alumni
  • Dr. med. Claudia Folba
  • Dr. med. Mareike Bernhard
  • Carla Vogeler, BSc
  • Azadda Nasruddin-Yekta, MD
  • Nina Gerkens (laboratory assistant)
  • Dr. rer. nat. Emilia Gomez-Molero
  • Abdelmalek Salem Ahlees, BSc
  • Yvonne Laukat (laboratory assistant)
  • Felix Yoppe, MSc
 ... and many students of the molecular biology oriented courses of study at the University of Göttingen.

Page updated on: 02.4.2024

  • Prof. Julian Naglik (King's College, London, UK)
  • Prof. Toni Gabaldon (BRC, Barcelona, ES)
  • Prof. Piet deGroot (CRIB, Ablacete, ES)
  • Dr. Jonathan Richardson (King's College, London, UK)
  • Jun. Prof Anne-Christine Hauschild (UMG, Göttingen, DE)
  • Prof. Timo Buhl (UMG, Göttingen, DE)
  • Dr. Christoph Sasse (GAUG, Göttingen, DE)

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