Bordetella pertussis Infection Attenuates Clinical Course of Acute Bronchiolitis

Background: Bordetella pertussis (BP) was detected in hospitalized children with various lower respiratory tract infections. The aim of this study was to assess clinical characteristics of BP infection, and its effect on disease severity in young children hospitalized with acute bronchiolitis. Methods: Included were previously healthy children <= 2 years of age who were hospitalized with acute bronchiolitis. In each patient, BP and 10 other possible pathogens were tested. Subjects were divided into 2 matched groups: cases in whom BP was detected, and controls in whom BP was not detected (ratio 1:4, respectively). Clinical parameters and clinical severity scores on admission and during hospitalization were compared between the 2 groups. Results: Overall, BP was detected in 24 of 309 (7.7 %) of children, 16 (67%) also with respiratory syncytial virus and 2 (8%) with BP as the sole pathogen. Cases compared with controls had lower rates of feeding problems before admission (30.5%, and 53.1%, respectively, P = 0.007). Upon admission, cases had a significantly lower percentage of combined "moderate" and "severe" clinical severity scores (13% versus 41.6% P = 0.001). The mean clinical severity score during hospitalization was also significantly lower in cases than controls (5.3 +/- 1.6 versus 5.8 +/- 1.5, respectively, P = 0.03). Conclusions: BP was detected in young children hospitalized with acute bronchiolitis mostly as a coagent. Children with BP infection had a lower disease severity both on admission and during hospitalization than those in whom BP was not detected.