The incidence and clinical effects of Bordetella pertussis in children hospitalized with acute bronchiolitis.

Background: Pertussis is a disease leading to high morbidity and mortality in neonates and infants. Bronchiolitis is the most common cause of hospitalization especially in children < 2 year-old. Although the clinical findings are different in these two diseases, it is sometimes difficult to make this distinction in partially or fully vaccinated children. This study aimed to identify the incidence, clinical and laboratory effects of B. pertussis as a causative agent in hospitalized children with acute bronchiolitis.

Methods: The study included patients diagnosed with acute bronchiolitis and admitted to the Division of Pediatric Infectious Diseases from January 2012 to December 2015, aged 24 months or younger, evaluated for viruses and bacteria with polymerase chain reaction in respiratory tract secretions.

Results: The study included 380 patients hospitalized with acute bronchiolitis. Of these patients, 85.8% were identified to be positive for at least one respiratory pathogen. The most commonly identified pathogens were respiratory syncytial virus (RSV) A/B, rhinovirus, parainfluenza virus, adenovirus, bocavirus and metapneumovirus A/B. B. pertussis was only detected in 5 patients (1.5%). In the patients with B. pertussis identified, coinfection with another virus was observed including rhinovirus (n= 2), influenza A virus (n= 1), coronavirus OC43 (n= 1) and RSV A/B (n= 1). The presence of B. pertussis did not appear to cause any significant clinical or laboratory differences in patients.

Conclusions: B. pertussis is a rare pathogen in patients admitted to hospital for acute bronchiolitis. However, in patients who do not respond to standard bronchiolitis treatment, B. pertussis should be considered as a causative agent. Early identification of this pathogen is important in terms of quarantining the patient, administering appropriate antimicrobial treatment, and prophylactic treatment to household and other close contacts.