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.