Bordetella Pertussis Infection in Hospitalized Infants with Acute Bronchiolitis

Objective To assess the frequency of B. pertussis infection among young infants hospitalized with acute bronchiolitis and to determine whether B. pertussis infection affects the clinical course of acute bronchiolitis. Methods A total of 172 infants <6 months of age hospitalized with acute bronchiolitis were tested for B. pertussis and respiratory viruses with real-time PCR. Cases were divided into 2 groups according to B. pertussis positive or negative. Clinical parameters, clinical severity scores and laboratory characteristics of the pertussis-positive and pertussis-negative cases were compared. Results Bordetella pertussis infection was detected in 44 (25.6%) of the 172 infants hospitalized for acute bronchiolitis, and as co-infection with respiratory viral agents in 27 (61.4%) infants. Of the 44 pertussis-positive infants, only 17 (38.6%) experienced a paroxysmal cough, 13 (29.5%) had whooping and 15 (34.1%) had post-tussive vomiting. There was no significant difference between pertussis-positive and pertussis-negative infants according to Wang clinical score at admission (4.9 +/- 1.5 vs. 5.2 +/- 2.5; p = 0.689). The overall disease severity score was also similar between the two groups (6.5 +/- 1.4 vs. 6.9 +/- 1.6; p = 0.095). Conclusions Bordetella pertussis infection is common in young infants hospitalized for acute bronchiolitis, mostly as co-infection with respiratory viruses. The clinical features of pertussis in the infants are not characteristic. Viral bronchiolitis and pertussis cases could not be differentiated by clinical findings. Co-infection with pertussis did not affect the clinical outcome in infants hospitalized with acute bronchiolitis.