Abstract G22

Genomic Fluidity of Bordetella pertussis: Genomic Mapping of Isolates

from a Recent Whooping Cough Outbreak in Alberta, Canada
Scott Stibitz, Mei-Shin Yang

We have used a technique called chromosomal surveying, recently developed in our laboratory, to analyze the genomic organization of fourteen Bordetella pertussis isolates from an outbreak of whooping cough which occured in Alberta, Canada from December, 1989 to May, 1991. This technique provides a map of the relative chromosomal positions of selected virulence genes of B. pertussis without regard to restriction enzyme clevage sites. The fourteen strains analyzed represent the 14 different electrophoretic types that were previously identified by pulsed-field gel electrophoresis (PFGE) of chromosomal XbaI digests (DeMoissac, Y. R., Ronald, S. L. , and M. S. Peppler, J. Clinical Microbiol. 32:398-402 (l994)). We have found at least eight different maps among the fourteen isolates suggesting that at least one explanation for the variation in XbaI digestion patterns involves chromosomal rearrangements. However, examples of isolates with different XbaI digestion patterns but identical maps were also found suggestion that creation and destruction of restriction sites may also be invloved. Our results are suggestive of a high degree of genomic fluidity in B. pertussis which may help to explain the high degree of variation in PFGE patterns which have previously been observed.