[Bordetella spp. infection: a 19-year experience in diagnosis by culture]

Abstract

Introduction: This retrospective study reviews the findings from cultures positive for Bordetella spp. obtained over a 19-year period, from January 1984 to December 2002.

Methods: Nasopharyngeal swabs were directly plated onto charcoal agar supplemented with 10% sheep blood and cephalexin (40 mg/L). Identification of suspected colonies was done by biochemical testing and slide agglutination with specific antisera for B. pertussis and B. parapertussis. The study includes microbiological findings and epidemiological data (age, sex, yearly distribution, seasonal period and number of inpatients and outpatients).

Results: The 2064 nasopharyngeal specimens yielded 269 positive cultures: B. pertussis was isolated from 244 patients, B. parapertussis from 23 and B. bronchiseptica from two. Among the positive patients, 36.9% were younger than 7 months, 38.8% were 7 months to 6 years old and 24.3% were older than 6 years of age.

Conclusions: The constant number of cases along the 19 years of the study shows that Bordetella spp. continues to circulate in our area. A high percentage of positive cultures were obtained from the group of children theoretically immunized by vaccination. Despite the low number of cases in young people and adults, adult pertussis seems to be a greater public health threat than was previously suspected and probably deserves to be further investigated. The gold standard for the diagnosis of Bordetella spp. infection is still recovery of the organism by culture, and it is especially useful for confirming outbreaks.