Epiglottitis (Haemophilus influenzae type b - Hib)
Overview
Plain-Language Overview
Epiglottitis (Haemophilus influenzae type b - Hib) is a serious infection that affects the epiglottis, a flap of tissue at the base of the tongue that helps protect the airway during swallowing. This condition primarily involves the throat and upper airway, causing swelling that can block airflow and make breathing difficult. It often develops quickly and can cause symptoms like severe sore throat, difficulty swallowing, and noisy breathing. Because the airway can become dangerously narrowed, emergency medical attention is often needed. The infection is caused by the bacteria Haemophilus influenzae type b, which used to be a common cause before widespread vaccination. Children are most commonly affected, but it can occur in adults as well. Prompt diagnosis and treatment are critical to prevent life-threatening airway obstruction.
Clinical Definition
Epiglottitis (Haemophilus influenzae type b - Hib) is an acute inflammation of the epiglottis and surrounding supraglottic structures caused predominantly by invasive infection with Haemophilus influenzae type b. The core pathology involves rapid mucosal edema and inflammation leading to potential airway obstruction. It is a medical emergency due to the risk of sudden respiratory compromise. The condition typically presents with fever, dysphagia, drooling, and stridor. Diagnosis is supported by clinical findings and confirmed by visualization of a swollen, cherry-red epiglottis on laryngoscopy or characteristic findings on lateral neck X-ray. The introduction of the Hib vaccine has dramatically reduced incidence, but it remains a critical diagnosis in unvaccinated or immunocompromised patients. Early recognition and airway management are essential to prevent morbidity and mortality.
Inciting Event
Colonization of the nasopharynx by Haemophilus influenzae type b precedes invasion.
Bacterial invasion through the mucosa of the epiglottis initiates the inflammatory process.
Upper respiratory viral infections may damage mucosal barriers, facilitating bacterial entry.
Close contact with infected individuals or asymptomatic carriers triggers transmission.
Latency Period
Symptoms typically develop within 1 to 3 days after bacterial invasion.
Rapid progression from initial sore throat to airway obstruction can occur within hours to a day.
The incubation period from exposure to symptom onset is usually 2 to 4 days.
Diagnostic Delay
Early symptoms mimic common viral pharyngitis, leading to misdiagnosis.
Fear of causing airway obstruction may delay throat examination and definitive diagnosis.
Lack of awareness in vaccinated populations can lead to low clinical suspicion.
Rapid progression of symptoms may outpace timely medical evaluation.
Clinical Presentation
Signs & Symptoms
Rapid onset of high fever and sore throat
Severe dysphagia and drooling
Muffled or 'hot potato' voice
Inspiratory stridor and respiratory distress
Anxiety and agitation due to hypoxia and airway obstruction
History of Present Illness
Initial presentation includes high fever, sore throat, and malaise.
Rapid onset of dysphagia, drooling, and muffled voice develops within hours.
Patients often adopt a tripod position to optimize airway patency.
Progressive stridor, respiratory distress, and cyanosis indicate worsening airway obstruction.
Past Medical History
Incomplete or absent Hib vaccination history is a key factor.
History of recent upper respiratory infections may be present.
Underlying immunodeficiency or chronic illnesses increase risk and severity.
No specific genetic predisposition is typically noted.
Family History
No known heritable syndromes are associated with epiglottitis.
Family members may be asymptomatic carriers of Hib, increasing transmission risk.
No familial clustering of epiglottitis beyond shared environmental exposure.
Physical Exam Findings
Tripod position with neck extended to improve airway patency
Drooling due to inability to swallow saliva
Stridor indicating upper airway obstruction
Muffled or hoarse voice from inflamed epiglottis
Tachypnea and use of accessory respiratory muscles
Fever reflecting systemic infection
Diagnostic Workup
Diagnostic Criteria
Diagnosis of epiglottitis is established by clinical presentation of rapid-onset sore throat, dysphagia, drooling, and respiratory distress with stridor. Definitive diagnosis is made by direct visualization of a swollen, erythematous epiglottis via laryngoscopy performed in a controlled setting to avoid airway compromise. A lateral neck X-ray may show the classic 'thumbprint sign' indicating epiglottic swelling. Blood cultures and throat swabs can identify Haemophilus influenzae type b, confirming the infectious etiology. Immediate recognition of these findings is critical for prompt airway management.
Pathophysiology
Key Mechanisms
Infection of the epiglottis and surrounding supraglottic structures by Haemophilus influenzae type b (Hib) leads to intense inflammatory edema and mucosal swelling.
Airway obstruction occurs due to the swollen epiglottis physically blocking the laryngeal inlet, causing respiratory distress.
Bacterial invasion triggers a robust neutrophilic inflammatory response with local tissue damage and potential for rapid progression.
Vascular congestion and submucosal edema further narrow the airway lumen, exacerbating symptoms of stridor and dyspnea.
| Involvement | Details |
|---|---|
| Organs | Epiglottis is the key organ affected, with inflammation causing the hallmark airway obstruction in epiglottitis. |
Larynx involvement contributes to airway narrowing and respiratory distress in severe cases. | |
| Tissues | Epiglottic mucosa is the primary site of infection and inflammation causing swelling and airway obstruction. |
Submucosal connective tissue becomes edematous due to increased vascular permeability during the inflammatory response. | |
| Cells | Neutrophils are the primary immune cells infiltrating the epiglottis, mediating acute inflammation and bacterial clearance. |
Macrophages participate in phagocytosis of Haemophilus influenzae and release pro-inflammatory cytokines. | |
Epithelial cells of the epiglottis become inflamed and edematous, contributing to airway obstruction. | |
| Chemical Mediators | Tumor necrosis factor-alpha (TNF-α) promotes local inflammation and vascular permeability in the epiglottis. |
Interleukin-1 (IL-1) enhances recruitment of immune cells and amplifies the inflammatory response. | |
Histamine released from mast cells contributes to mucosal edema and airway narrowing. |
Treatments
Pharmacological Treatments
Third-generation cephalosporins (e.g., ceftriaxone)
- Mechanism:
Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins, leading to bacterial lysis.
- Side effects:
Allergic reactions
Diarrhea
Phlebitis at injection site
- Clinical role:
First-line
Vancomycin
- Mechanism:
Inhibits bacterial cell wall synthesis by binding to D-Ala-D-Ala terminus of cell wall precursors, effective against resistant strains.
- Side effects:
Nephrotoxicity
Ototoxicity
Red man syndrome
- Clinical role:
Second-line
Corticosteroids (e.g., dexamethasone)
- Mechanism:
Reduce airway inflammation and edema by suppressing pro-inflammatory cytokine production.
- Side effects:
Hyperglycemia
Immunosuppression
Gastrointestinal bleeding
- Clinical role:
Adjunctive
Non-pharmacological Treatments
Secure airway promptly via endotracheal intubation or tracheostomy if airway obstruction is imminent.
Provide supportive care including oxygen supplementation and close monitoring in an intensive care setting.
Prevention
Pharmacological Prevention
Hib conjugate vaccine administered in infancy to prevent invasive Haemophilus influenzae type b infections
Prophylactic rifampin for close contacts of patients with invasive Hib disease
Non-pharmacological Prevention
Routine childhood immunization schedules to ensure Hib vaccine coverage
Avoidance of exposure to respiratory pathogens in young children
Early recognition and treatment of upper respiratory infections to prevent progression
Public health measures to reduce transmission of Haemophilus influenzae
Outcome & Complications
Complications
Acute airway obstruction leading to respiratory failure
Bacteremia and sepsis from Haemophilus influenzae type b
Pneumonia as a secondary infection
Abscess formation in the deep neck spaces
Death if airway is not promptly secured
| Short-term Sequelae | Long-term Sequelae |
|---|---|
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Differential Diagnoses
Epiglottitis (Haemophilus influenzae type b - Hib) versus Croup (Laryngotracheobronchitis)
Epiglottitis (Haemophilus influenzae type b - Hib) | Croup (Laryngotracheobronchitis) |
|---|---|
Typically affects children aged 2 to 7 years | Commonly affects children aged 6 months to 3 years |
Rapid onset with high fever and severe respiratory distress | Gradual onset with mild fever and barking cough |
Thumbprint sign on lateral neck X-ray indicating swollen epiglottis | Steeple sign on neck X-ray indicating subglottic narrowing |
Caused by Haemophilus influenzae type b (Hib) bacteria | Usually caused by parainfluenza virus |
Epiglottitis (Haemophilus influenzae type b - Hib) versus Peritonsillar Abscess
Epiglottitis (Haemophilus influenzae type b - Hib) | Peritonsillar Abscess |
|---|---|
Elevated white blood cell count with neutrophilia but no tonsillar exudate | Elevated white blood cell count with neutrophilia and purulent tonsillar exudate |
Lateral neck X-ray shows enlarged, swollen epiglottis without abscess | CT scan shows unilateral peritonsillar fluid collection |
Rapid onset of dysphagia, drooling, and muffled voice without trismus | Progressive sore throat with uvular deviation and trismus |
Epiglottitis (Haemophilus influenzae type b - Hib) versus Retropharyngeal Abscess
Epiglottitis (Haemophilus influenzae type b - Hib) | Retropharyngeal Abscess |
|---|---|
More common in children aged 2 to 7 years | More common in children under 6 years |
Lateral neck X-ray shows thumbprint sign from epiglottic swelling | Lateral neck X-ray shows widened prevertebral space |
Rapid onset with high fever and severe respiratory distress | Gradual onset with neck stiffness and fever |
Epiglottitis (Haemophilus influenzae type b - Hib) versus Bacterial Tracheitis
Epiglottitis (Haemophilus influenzae type b - Hib) | Bacterial Tracheitis |
|---|---|
Caused by Haemophilus influenzae type b (Hib) | Commonly caused by Staphylococcus aureus |
Primary bacterial infection with rapid onset of airway obstruction | Follows viral upper respiratory infection with worsening airway obstruction |
Enlarged, swollen epiglottis on lateral neck X-ray | Subglottic narrowing with irregular tracheal mucosa on imaging |
Epiglottitis (Haemophilus influenzae type b - Hib) versus Foreign Body Aspiration
Epiglottitis (Haemophilus influenzae type b - Hib) | Foreign Body Aspiration |
|---|---|
No choking episode; gradual onset of symptoms | History of choking episode or witnessed aspiration |
Progressive dysphagia and respiratory distress over hours | Sudden onset of coughing, wheezing, or stridor |
Lateral neck X-ray shows thumbprint sign from epiglottic swelling | Chest X-ray may show localized air trapping or radiopaque object |