Molecular epidemiology of Bordetella pertussis by DNA fingerprinting with pulsed-filled gel electrophoresis, 1989-1996

ABSTRACT

Pertussis is an endemic disease in the United States of America, with epidemics occurring every three to four years. In Cincinnati, Bordetella pertussis isolates collected from 1989 to 1996 were analysed by genomic subtyping with pulsed-field gel electrophoresis (PFGE) to evaluate the B pertussis population before, during and after a large epidemic of epidemiologically relevant changes. Among the 496 B pertussis isolates, 31 PFGE profiles were identified; 32 percent of isolates were CYXXI-010 and this profile predominated in each year. Nineteen, 20 and 12 PFGE profiles were identified in the pre-epidemic period (n=198), during the epidemic (n = 197) and in the post-epidemic period (n = 101), resulting in genotypic diversities of 0.82, 0.83 and 0.76 respectively. From 1989 to 1996, among 19 households clusters of 42 patients, 17 (89 percent) households had concordant PFGE profiles among isolates from household members. There was no association between PFGE type and seasonality, age, hospitalisation or pneumonia in infants. The 1993 epidemic was primarily associated with increased prevalence of B pertussis PFGE profiles that circulated before and after the epidemic, suggesting increased susceptibility to pertussis rather than a novel strain as a cause of the outbreak.(Au)