1. Department of Medical Microbiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam,1 and
2. Reference Laboratory for Bacterial Meningitis, University of Amsterdam/RIVM, 1100 DE Amsterdam,2 The Netherlands;
3. Max-Planck Institut für Molekulare Genetik, D14195 Berlin, Germany3; and
4. World Health Organization Collaborating Centre for Reference and Research on Meningococci, Department of Bacteriology, National Institute of Public Health, N-0403 Oslo, Norway4