Dr. E.C.J. (Eric) Claas

Molecular Medical Microbiologist, Molecular Diagnostics


  • Etiology of respiratory and gastrointestinal infections
  • Clinical relevance of molecular diagnostics
  • Automation of the molecular diagnostic workflow
  • Syndromic and rapid testing
  • The role of NGS in diagnostic microbiology


Department of Medical Microbiology
Molecular Medical Microbiologist

Research interests

The Molecular Diagnostics lab of the clinical microbiology lab is specialized in implementation of molecular assays for diagnosis of infections in the whole field of microbiology, and by now more  than 100 real-time PCR assays have been implemented in the diagnostic lab. Using multiplex applications up to five different targets, the focus can be more syndrome related than pathogen related. For respiratory infections and gastroenteritis, viruses, bacteria and parasites are tested simultaneously to rapidly identify the cause.
Currently, laboratory automation and further improvements in laboratory efficiency and service are high on the agenda. Recently rapid syndromic test panels have been implemented to increase the time to results for respiratory testing.
Furthermore the possibilities of Next Generation sequencing in Molecular Diagnostic practice are being explored. For bacterial typing in infection control, cgMLST and wgSNP analysis have been developed for some of the major outbreak related micro-organisms.
In addition, protocols metagenomic WGS in detection of pathogens are being optimized.

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Professional biosketch

Eric C.J. Claas has a long standing experience in development and implementation of molecular diagnostic tests in the clinical microbiology laboratory. Already in 1991, clinical application of the PCR for detection of HPV and Chlamydia was the topic of his PhD thesis. Subsequently, he worked for eight years at the Dutch National Influenza centre (Erasmus University, Rotterdam) where his group identified the first human H5N1 (bird-flu) infection in 1997. Since 1998, he is heading the molecular diagnostics section of the Department of Medical Microbiology at the LUMC, Leiden, The Netherlands. In this lab, molecular assays are performed for all areas of microbiology, i.e. virology, bacteriology, parasitology and mycology. In addition, testing is performed for antimicrobial and antiviral resistance, genotyping including bacterial typing for hospital epidemiology and ribotyping as part of the Clostridium reference lab function. He is coordinator of the NGS activities of the departments and closely involved in implementation of innovative new molecular approaches.  

He published his research in almost 200 papers in peer-reviewed scientific journals and books and has been involved in diagnostic assay development and implementation of these assays in several EU funded projects.

He holds two consultancy positions in two other Dutch hospitals: the Medical Center Slotervaart in Amsterdam and the Franciscus Gasthuis and Vlietland in Rotterdam.

He is auditor for iso15189 and iso17025 guidelines for the Dutch Accreditation Council (RVA). He has been member in national expert committees on influenza vaccination as well as the National Society for Health Insurance. In the Dutch society for Medical Microbiology, he is former president of the Working Group on Molecular Diagnostics (WMDI) and current chairman of concilium for trainees Molecular Medical Microbiologists. In addition he is treasurer of the ESCMID study group of Genomic and Molecular Diagnostics and board member of the VMDG (Council for Molecular Diagnostics in Health Care).

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Selected publications


 Hetem, D.J., I. Bos-Sanders, R.H.T. Nijhuis, S. Tamminga, L. Berlinger, E.J. Kuijper, J.J. Sickler, and E.C.J. Claas. Evaluation of the Liat Cdiff Assay for direct detection of Clostridiodes difficile toxin genes within 20 minutes. Journal of Clinical Microbiology 2019; 57: e00416-19. https://doi.org/10.1128/JCM.00416-19


Ieven, M.,S. Coenen, K. Loens, C. Lammens, F. Coenjaerts, A. Vanderstraeten,  B. Henriques-Normark , D. Crook, K. Huygen, C.C. Butler, T.J. Verheij, P. Little, K. Zlateva, A. van Loon , E.C. Claas, and H. Goossens, on behalf of the GRACE consortium,. Aetiology of Lower Respiratory Tract Infection in Adults in Primary Care: A prospective Study in 11 European Countries, Clinical Microbiology andInfection  2018;24:1158-1163 https://doi.org/10.1016/j.cmi.2018.02.004


van Rijn, AL, RHT Nijhuis, V Bekker, GH Groeneveld, E Wessels, MCW Feltkamp, and ECJ Claas. Clinical implications of rapid ePlex® Respiratory Pathogen Panel testing compared to laboratory-developed real-time PCR. Eur J Clin Microbiol Infect Dis (2016). https://doi.org/10.1007/s10096-017-3151-0

Terveer, EM, RHT Nijhuis, MJT Crobach, CW Knetsch, KE Veldkamp, JGooskens, EJ Kuijper, and ECJ Claas.
Prevalence of colistin resistance gene (mcr-1) containing Enterobacteriaceae in feces of patients attending a tertiary care hospital and detection of a mcr-1 containing, colistin susceptible E. coli. PLOS ONE 2017 https://doi.org/10.1371/journal.pone.0178598

Beek, M.T. van der and E.C.J. Claas.
Phenotypic and genotypic antiviral susceptibility testing. In: Clinical Virology Manual 2016. Loeffelholz, Hodinka, Young and Pinsky (eds) Fifth Edition, Chapter 16, p201-227.

Zlateva, KT, JJC de Vries, FEJ Coenjaerts, AM van Loon, T Verheij, P Little, CC Butler, H Goossens, M Ieven  and ECJ Claas on behalf of the GRACE Study Group. Prolonged shedding of rhinovirus and re-infection in adults with respiratory illness. European Respiratory Journal 2014: 44; 169-177.
https://doi.org/10.1183/09031936.00172113. Erratum 2014: 44: 556.

Wessels, E, LG Rusman, MJAWM van Bussel and ECJ Claas. Added value of multiplex Luminex Gastrointestinal Pathogen Panel (xTAG® GPP) testing in the diagnosis of infectious gastroenteritis.
Clinical Infectious Diseases 2014; 20:0182-0187.


Wessels E, Schelfaut JJ, Bernards AT, Claas ECJ. Evaluation of several biochemical and molecular techniques for identification of Streptococcus pneumoniae and Streptococcus pseudopneumoniae and their detection in respiratory samples. J Clin Microbiol. 2012; 50:1171-1177.


de Vries JJC, Barbi M, Binda S, Claas ECJ. Extraction of DNA from dried blood in the diagnosis of congenital CMV infection. In: Diagnosis of Sexually Transmitted Diseases: Methods and Protocols. Methods Mol Biol. 2012; 903:169-175.


van Maarseveen NM, Wessels E, de Blij- Brouwer CS, Vossen ACTM, Claas ECJ. Diagnosis of viral gastroenteritis by simultaneous detection of Adenovirus group F, Astrovirus, Rotavirus group A, Norovirus genogroups I and II, and Sapovirus in two internally controlled multiplex real-time PCR assays. J Clin Virol. 2010; 49:205-210.


van Veen SQ, Claas ECJ, Kuijper EJ. High-throughput identification of bacteria and yeast by matrix-assisted laser desorption ionization mass spectrometry (MALDI-TOF MS) in routine medical microbiology laboratory. J Clin Microbiol. 2010; 48:900-907.


All publications by Eric C.J. Claas in PubMed

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Leids Universitair Medisch Centrum
Gebouw 1
Kamer E4-56

Albinusdreef 2
2333 ZA Leiden
Tel: +31(0)715263650

Postzone E4-P
Postbus 9600
2300 RC Leiden

E-mail: e.claas@lumc.nl