Sub theme 4.4
Infections due to bacteria, fungi and parasites: diagnosis, molecular mechanisms, epidemiology, therapy and prevention

Goals of research: general outline
Scientific achievements
Future plans: special goals and approach
Running projects
Associated staff

Workgroup leaders   Department
Dr.  H. Ph.  Endtz   Medical Microbiology & Infectious Disease

Goals of research: general outline

Main focus of our recent research has been the investigation into the basic aspects of human nasal carriage of the opportunistic pathogen Staphylococcus aureus. We have defined human S. aureus nasal carriage patterns in microbiological detail. Via culture-based surveillance we can reliably discriminate between persistent and non-carriers and we have identified a number of human phenotypes that are important in establishing long-lasting colonization. These include blood glucose levels, smoking habits, gender and a variety of other parameters. In addition, we identified the first human genetic polymorphisms associated with persistent staphylococcal carriage. This emphasises the importance of host involvement in the colonization process. Recently, we have genetically solved the population structure of S. aureus strains derived from a non-clinical origin. We provided evidence that essentially any S. aureus genotype carried by humans can transform into a life-threatening pathogen but that certain clones may be even more virulent than others. In addition, in several translational studies we defined the clinical significance of genomic variability of S. aureus and validated several S. aureus molecular typing methods. Simultaneously, molecular diagnostic methods were developed and implemented. Using both the epidemiological and diagnostic methodologies we have been able to identify molecular markers important in S. aureus host specificity. Finally, we have demonstrated that host bacterium interplay is highly specific: hosts have a very clear preference for their “own” strain rather than alien isolates. While performing these studies we initiated the development of a unique human nasal colonization model.

In addition, the applicant is involved in various other translational and fundamental research projects. The development of innovative microbiological diagnostics and epidemiological typing strategies has been a continuous and scientifically productive effort over the past fifteen years. Current diagnostic and epidemiological foci involve the use of Raman and mass spectroscopy and the application of electronic nose devices. Animal models for the assessment of the therapeutic efficacy of novel antimicrobial agents and therapies have been developed and are used for identification of novel anti-infective, curative procedures.

In addition, basic research in the field of Campylobacter jejuni-induced neuropathogenesis has led to the identification of several bacterial markers for disease progression. The discovery of the involvement of the bacterial lipooligosaccharides (LOS) and its encoding genes has been the most important highlight of our studies. Some of these factors are currently being translated into innovative therapeutic approaches.

The etiology of mycetoma caused by the fungus Madurella mycetomatis has been explored as part of our collaborations with researchers from developing countries. We have developed diagnostic and typing tools, elucidated immunological response patterns in infected individuals and described the ecological spread of the fungus. In addition we unravelled some of the basic human genetic polymorphisms that predispose to the development of this devastating disease.

Scientific achievements
  1. Established human nasal colonization model for S. aureus.
  2. Solved population structure of S. aureus from non-clinical sources.
  3. Initiated genome wide association studies relating to S. aureus nasal carriage.
  4. Developed Raman spectroscopy for epidemiological typing of bacterial pathogens.
  5. Developed electronic nose device for direct microbial diagnostics.
  6. Identified C. jejuni LOS as THE molecular determinant for Guillain-Barré Syndrome.
  7. Identified human genomic markers for Madurella mycetomatis infection susceptibility.

Future plans: special goals and approach
  1. We intend to further refine our human colonization model for S. aureus.
  2. We will acquire genomics and transcriptomics technology to study S. aureus gene expression in vivo, ex vivo and in vitro.
  3. We will finalise GWA studies in collaboration with two international cohorts in which S. aureus carriage is also assessed.
  4. We will develop novel diagnostic assays based on Raman, electronic nose and MS technology, both for bacterial detection and identification as well as for antimicrobial susceptibility testing.
  5. We will further elaborate on novel C. jejuni markers for GBS; candidates are the CRISPR locus and the CRISPR associates cas genes.
  6. We will develop a prospective cohort study in Sudan in order to analyse the etiology, diagnostics, therapy and molecular basis of Madurella mycetomatis associated mycetoma.

Most recent publications
  1. Daubersies Pierre, Thomas Alan, Millet Pascal, Brahimi Karima, Langermans Jan, Ollomo Benjamin, Ben Mohamed Lbachir, Slierendregt Bas, Eling Wijnand, Belkum Alex van, Meis Jacques, Guerin-Marchand Claudine, Cayphas Sylvie, Cohen Joe, Gras-Masse Helene and Druilhe Pierre (2000) Protection against Plasmodium falciparum malaria in chimpanzees by immunization with the conserved pre-erythrocytic liver-stage 3 antigen. Nature Medicine 6, 1258-1263. (IF 26.4)
  2. Belkum Alex van, Braak Nicole van den, Godschalk Peggy, Ang Wim, Jacobs Bart, Gilbert Michel, Wakarchuk Warren, Verbrugh Henri and Endtz Hubert (2001) “A Campylobacter jejuni gene associated with immune mediated neuropathy”. Nature Medicine, 7, 752-753. (IF 26.4)
  3. Belkum Alex van, and Verbrugh Henri (2001) “Forty years of methicillin resistant Staphylococcus aureus: MRSA is here to stay – but it can be controlled.” British Medical Journal 323, 644-645. (IF 9.7)
  4. Godschalk Peggy, Heikema Astrid, Gilbert Michel, Komagamine Tomoko, Ang Wim, Glerum Jobine, Brochu Denis, Li Jiangjun, Yuki Nobuhiro, Jacobs Bart, Belkum Alex van, Endtz Hubert (2004) “The crucial role of Campylobacter jejuni genes in anti-ganglioside antibody induction in Guillain-Barre Syndrome”. Journal of Clinical Investigation 114, 1659-1665. (IF 16.9)
  5. Melles Damian, Gorkink Raymond, Boelens Helene, Snijders Susan, Peeters Justine, Moorhouse Michael, Spek Peter van der, Leeuwen Willem van, Simons Guus, Verbrugh Henri, Belkum Alex van (2004) “Natural population dynamics and expansion of pathogenic clones of Staphylococcus aureus”. Journal of Clinical Investigation 114, 1732-1740. (IF 16.9)
  6. Bogaert Debbie, Belkum Alex van, Sluijter Marcel, Luijendijk Ad, Groot Ronald de, Rumke Hans, Verbrugh Henri, Hermans Peter (2004) “Colonisation by Streptococcus pneumoniae and Staphylococcus aureus in healthy children”. Lancet 363, 1871-1872. (IF 28.6)
  7. Wertheim Heiman, Vos Margreet, Ott Alewijn, Belkum Alex van, Voss Andreas, Kluytmans Jan, Keulen Peter van, Vandenbroucke-Grauls Christina, Meester Marlene, Verbrugh Henri (2004) “Risk and outcome of nosocomial Stapohylococcus aureus bacteremia in nasal carriers versus non-carriers”. Lancet 364, 703-705. (IF 28.6)
  8. Wertheim Heiman, Vos Greet, Leeuwen Willem van, Belkum Alex van, Verbrugh Henri, Nouwen Jan (2005) “The role of nasal carriage in Staphylococcus aureus infection. Lancet Infectious Diseases 5, 751-762. (IF 12.1)
  9. Wirth Thierry, Morelli Giovanna, Kusecek Barica, Belkum Alex van,Schee Cindy van der, Meyer Axel, Achtman Mark (2007) “The rise and spread of a new pathogen: seroresistant Moraxella catarrhalis”. Genome Research 17:1647-1656. (11.2)
  10. Wertheim Heiman, Walsh Evelyn, Choudhurry Roos, Melles Damian, Boelens Helene, Miajlovic Hanna, Verbrugh Henri, Foster Tim, van Belkum Alex (2008) “Key role for clumping factor B in Staphylococcus aureus nasal colonization of humans”. PLoS Medicine 5:e17. (12.6)
  11. The complete genome sequence of Campylobacter jejuni strain 81116 (NCTC11828).
    Pearson BM, Gaskin DJ, Segers RP, Wells JM, Nuijten PJ, van Vliet AH. J Bacteriol. 2007 Nov;189(22):8402-3. Epub 2007 Sep 14.
  12. Iron-responsive repression of urease expression in Helicobacter hepaticus is mediated by the transcriptional regulator Fur. Belzer C, van Schendel BA, Kuipers EJ, Kusters JG, van Vliet AH. Infect Immun. 2007 Feb;75(2):745-52. Epub 2006 Nov 13.
  13. Helicobacter pylori and antimicrobial resistance: molecular mechanisms and clinical implications. Gerrits MM, van Vliet AH, Kuipers EJ, Kusters JG. Lancet Infect Dis. 2006 Nov;6(11):699-709. Review.
  14. Helicobacter pylori HopH (OipA) and bacterial pathogenicity: genetic and functional genomic analysis of hopH gene polymorphisms. Dossumbekova A, Prinz C, Mages J, Lang R, Kusters JG, Van Vliet AH, Reindl W, Backert S, Saur D, Schmid RM, Rad R. J Infect Dis. 2006 Nov 15;194(10):1346-55. Epub 2006 Oct 10.
  15. Urease induced calcium precipitation by Helicobacter species may initiate gallstone formation. Belzer C, Kusters JG, Kuipers EJ, van Vliet AH. Gut. 2006 Nov;55(11):1678-9. No abstract available.
  16. Pathogenesis of Helicobacter pylori infection. Kusters JG, van Vliet AH, Kuipers EJ. Clin Microbiol Rev. 2006 Jul;19(3):449-90. Review.