Haemophilus influenzae infection
Haemophilus influenzae is a gram-negative coccobacillus whose encapsulated type b (Hib) strain historically caused invasive childhood disease (epiglottitis, meningitis, bacteremia) before routine vaccination, while nontypeable strains now dominate as a cause of mucosal infections (otitis media, sinusitis, COPD exacerbation, pneumonia). Epiglottitis is a clinical airway emergency treated by securing the airway before diagnostic workup, and invasive disease is treated with a third-generation cephalosporin.
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What this article covers
- Overview
Haemophilus influenzae is a small gram-negative coccobacillus that causes two distinct clinical pictures: historically, the encapsulated type b (Hib) strain caused invasive disease in unvaccinated…
- Epidemiology
Widespread Hib conjugate vaccination has dramatically reduced invasive H.
- Risk factors
Incomplete or absent Hib vaccination, particularly in a child under 4 years old, is the dominant risk factor for invasive Hib disease.
- Pathophysiology
The type b polysaccharide capsule (polyribosylribitol phosphate) is the principal virulence factor of invasive disease, allowing the organism to resist phagocytosis and opsonization, particularly in…
- Clinical features
Epiglottitis presents with acute-onset high fever (39-40 C), dysphagia, drooling, and inspiratory distress (the "three D's": dysphagia, drooling, distress), with a muffled "hot potato" voice and soft…
- Differential diagnosis
Croup (viral laryngotracheitis): a barking cough, hoarseness, and inspiratory stridor with a more gradual onset over days, distinguished from epiglottitis by the absence of drooling and toxic…
- Diagnosis
Epiglottitis is a clinical diagnosis established by the acute high fever, drooling, dysphagia, and tripod positioning, with the airway secured before any confirmatory test is attempted; other H.
- Management
First, for suspected epiglottitis, secure the airway immediately by endotracheal intubation or, if intubation fails, tracheostomy, performed in the operating room with anesthesia and otolaryngology…
- Complications
Airway obstruction and respiratory arrest are the most immediately life-threatening complications of untreated epiglottitis.
- Prognosis
Epiglottitis has an excellent prognosis once the airway is secured and appropriate antibiotics are started, but untreated airway obstruction can be rapidly fatal.
- Prevention
Give the conjugate Hib vaccine (type b capsular polysaccharide conjugated to a carrier protein) on the routine schedule between 2 and 18 months of age, the single most effective measure against invasive Hib disease.
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