Abstract

Bordetella pertussis Strains Circulating in Europe in 1999 to 2004 as Determined by Pulsed-Field Gel Electrophoresis ▿ Hans Hallander 1 , Abdolreza Advani 1 , Marion Riffelmann 2 , Carl H. W. von König 2 , Valerie Caro 3 , Nicole Guiso 3 , Frits R. Mooi 4 , Anna Gzyl 5 , Margit S. Kaltoft 6 , Norman K. Fry 7 , Jussi Mertsola 8 and Qiushui He 9 , * 1 Department of Immunology and Vaccinology, Swedish Institute for Infectious Disease Control, SMI, Solna, Sweden 2 Institut für Infektiologia Krefeld GmbH, Krefeld, Germany 3 Institut Pasteur, Unité PTMMH, URA 3012, 25 rue du Dr. Roux, 75015 Paris, France 4 Laboratory for Infectious Diseases and Screening (LIS), National Institute of Public Health and the Environment, Bilthoven, The Netherlands 5 Department of Sera and Vaccine Evaluation, National Institute of Hygiene, Warsaw, Poland 6 Statens Serum Institut, Copenhagen, Denmark 7 Respiratory and Systemic Infection Laboratory, Health Protection Agency Centre for Infections, London, United Kingdom 8 Department of Pediatrics, University of Turku, Turku, Finland 9 Pertussis Reference Laboratory, National Public Health Institute, Turku, Finland ABSTRACT Clinical isolates of Bordetella pertussis collected during the year 2004 ( n = 153) in eight European countries, Denmark, Finland, France, Germany, The Netherlands, Poland, Sweden, and United Kingdom, were analyzed by pulsed-field gel electrophoresis (PFGE), and their PFGE profiles were compared with those of isolates collected in 1999 ( n = 102). The 255 isolates produced 59 distinct PFGE profiles. Among the 153 isolates from 2004, 36 profiles were found, while within the 102 isolates from 1999, 33 profiles were detected. One PFGE profile, BpSR11, was dominant (30% to 50%) in all countries except Denmark (10%) and Poland (0%). In comparison with 1999, there was an increase in BpSR11 prevalence in Finland in 2004 from 5% to 40%, coinciding with a major incidence peak. Some other PFGE profiles seemed to be associated with limited dissemination. Poland was the only country in which the most common actual European PFGE profiles were not found. In a dendrogram analysis, all common PFGE profiles were identified within PFGE group IV, and BpSR11 clustered together with PFGE subgroup IVβ. Compared to the 1999 isolates, PFGE group V representative for pertactin variant prn3 strains had disappeared, and a new cluster was seen. In conclusion, some PFGE profiles, such as BpSR11, evidently have a higher capacity to spread, suggesting increased fitness to the present immunological environment. It is therefore of major interest to continue with surveillance programs of B. pertussis isolates, as both waning vaccine-derived immunity and strain variation may play a role in the persistence of pertussis.