Molecular epidemiology of Bordetella pertussis by pulsed-field gel electrophoresis profile: Cincinnati, 1989-1996

Reported cases of pertussis have increased in the United States, with peaks occurring every few years. Bordetella pertussis isolates collected in Cinc innati from 1989 to 1996 were analyzed with pulsed-field gel electrophoresi s (PFGE), to evaluate trends. Among 496 isolates, 30 PFGE profiles were ide ntified; 32% were CYXXI-010, the profile that predominated each year. Eight een profiles (198 strains) were identified in 1989-1992, 20 profiles (197 s trains) were identified during the 1993 epidemic, and 11 profiles (101 stra ins) were identified in 1994-1996. From 1989 to 1996, among 42 patients, is olates from household members in 17 (89%) of 19 households had concordant P FGE profiles. There was no association between PFGE profile and seasonality , age, and hospitalization or pneumonia in infants <1 year old. The 1993 ep idemic was associated primarily with an increased prevalence of PFGE profil es that circulated before and after 1993, which suggests that the epidemic was due to factors other than the emergence of a novel B. pertussis strain.