Pulsed-field gel electrophoresis analysis of Bordetella pertussis populations in various European countries with different vaccine policies

The increasing incidence of pertussis in a number of countries, despite good vaccination coverage, is a cause for concern. We used pulsed-field gel electrophoresis (PFGE) typing to examine the genetic diversity of 101 clinical isolates of Bordetella pertussis, recovered during 1999-2001, and circulating in five different European countries to evaluate temporal and geographical distribution. This DNA fingerprinting approach seems to be a more discriminative epidemiological tool than sequencing of individual genes. Despite differences in vaccination policies in the five countries, these European isolates were found to be very similar and fell into the same major PFGE profile groups, with a predominance of one profile group. There was no evidence of geographic clustering, except that one new profile subgroup was predominantly found in one country. This study provides a baseline for continued surveillance of the B. pertussis population in Europe.