Description

• Acute, life-threatening upper airway obstruction due to infraglottic bacterial infection following a primary viral infection (typically parainfluenza or influenza)
• Historically high mortality rates of up to 20% in children; more recent evidence suggests lower mortality rates, as low as 2.7% in the Casazza et al. case series (1). Improving prompt recognition and airway management has lowered mortality; however, it can still result in severe, acute, upper airway obstruction and death.
• Affects two major groups of patients in the pediatric age range
  • Those with a native intact airway
  • Those with an artificial airway
• Often preceded by viral infection, such as influenza, parainfluenza, or respiratory syncytial virus
• Staphylococcus is the most common bacteria identified in those with an intact native airway.
• Diagnostic hallmarks on endoscopy: ulceration, pseudomembranes in the trachea with thick mucopurulent exudates, and mucosal sloughing that can cause airway obstruction
• System(s) affected: pulmonary
• Synonym(s): laryngotracheobronchitis; bacterial croup; pseudomembranous croup

Epidemiology

Etiology and Pathophysiology

• Methicillin-sensitive S. aureus (MSSA) accounted for 33% of cases and Haemophilus influenzae 12.1% in Barengo et al. cohort study (2)
• Mixed respiratory flora
• Streptococcus pneumoniae
• In children with artificial airway, most common organisms in order of frequency are Pseudomonas aeruginosa, S. aureus, H. influenzae, S. pneumoniae, and other gram-negative organisms.
• Viral-induced injury to the respiratory epithelium in conjunction with localized immune impairment can predispose individuals to bacterial superinfection.

Risk Factors

• Periods of increased seasonal activity of respiratory viruses
• Reports following tonsillectomy, adenoidectomy, with chronic tracheal aspiration, and with evidence of other concurrent infections, including sinusitis, otitis, pneumonia, or pharyngitis
• Presence of an artificial airway

General Prevention

• Standard precautions, with scrupulous attention to handwashing
• Age-appropriate Centers for Disease Control and Prevention (CDC) scheduled pediatric immunization against H. influenzae and viruses that may predispose to bacterial tracheitis

Commonly Associated Conditions

• Consider anatomic abnormalities, foreign bodies, as well as recent pharyngeal or laryngeal surgery.
• Predisposing: Down syndrome, immunodeficiency, subglottic hemangioma, tracheoesophageal fistula repair, tracheobronchomalacia
• More common in children with tracheostomy
• Viral coinfection may occur.