Bacterial Tracheitis and Retropharyngeal Abscess
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Direct answer
Bacterial tracheitis is a severe infection of the trachea, usually following viral croup, in which thick purulent secretions and sloughed mucosa obstruct the airway. Retropharyngeal abscess is a collection of pus behind the pharynx, usually in children under five, presenting with neck stiffness, dysphagia and fever. Both need antibiotics and airway support, and contrast CT of the neck defines a retropharyngeal collection that needs drainage.
What you must remember
- Organisms in tracheitis: Staphylococcus aureus, including MRSA, streptococci, Moraxella catarrhalis and Haemophilus influenzae.
- Biphasic course: apparent recovery from croup, followed after a day or two by high fever, toxicity and worsening stridor.
- Radiograph in tracheitis: an irregular, ragged subglottic tracheal outline on the neck film, alongside the findings of croup.
- Treatment of tracheitis: IV antibiotics covering Staphylococcus aureus and common respiratory pathogens, with early anaesthetic input because intubation may be needed.
- Presentation of retropharyngeal abscess: fever, neck stiffness, torticollis, drooling, dysphagia and muffled voice, which can progress to airway compromise.
- Imaging of retropharyngeal abscess: contrast CT of the neck is the investigation of choice; a lateral neck radiograph may show a widened prevertebral shadow but is non-specific.
- Organisms and treatment of abscess: mixed flora including Staphylococcus aureus, group A streptococci and anaerobes, treated with IV antibiotics plus surgical or image-guided drainage.
A stepwise approach to a child with stridor after croup
A 4-year-old has three days of croup, seems to improve, then deteriorates with high fever and stridor at rest. The sequence below keeps the airway safe while the diagnosis is confirmed.
- Recognise the biphasic course. Improvement followed by fever and toxicity points to bacterial tracheitis rather than simple viral croup.
- Secure the airway first. Involve anaesthesia early, because the lumen may be narrowed by secretions and intubation may be needed.
- Image the neck. Radiographs show subglottic narrowing with a ragged outline in tracheitis, and contrast CT looks for retropharyngeal or deep neck collections.
- Start antibiotics. Give IV cover for Staphylococcus aureus with a broad-spectrum agent, then adjust to local resistance patterns and culture results.
- Drain collections and watch for spread. A retropharyngeal abscess needs surgical or image-guided drainage with antibiotics covering anaerobes, and mediastinal spread must be excluded.
Tracheitis and retropharyngeal abscess can coexist with deep neck infection, so both should be considered when stridor and neck pain occur together. Early anaesthetic input and imaging must run in parallel, and the airway always comes first.
Where the exam tries to catch you
Three errors cost marks on this topic.
- Trap: labelling stridor after croup as simple croup Correct: a biphasic course with fever and toxicity suggests bacterial tracheitis, which needs IV antibiotics and airway planning.
- Trap: using a normal lateral neck film to exclude retropharyngeal abscess Correct: a plain film cannot exclude it, and contrast CT is preferred when suspicion is high.
- Trap: probing the throat to look for the abscess Correct: manipulation can rupture the collection and cause aspiration, so examine gently and image instead.
Frequently asked questions
What distinguishes bacterial tracheitis from simple croup?
Bacterial tracheitis differs from simple croup by its biphasic course, with apparent improvement followed by high fever, toxicity and worsening stridor. Its radiograph can show an irregular subglottic tracheal outline, and cultures often grow Staphylococcus aureus.
Which investigation is best for a retropharyngeal abscess?
Contrast-enhanced CT of the neck is the best investigation for a retropharyngeal abscess, because it defines the collection and its extent. A plain lateral neck radiograph can show a widened prevertebral shadow but cannot reliably confirm or exclude an abscess.
At what age does retropharyngeal abscess usually occur?
Retropharyngeal abscess usually occurs in children under five years, when retropharyngeal lymph nodes are prominent and infection spreads from the upper airway. Older children and adults can be affected, though less often.
Why is retropharyngeal abscess a dangerous diagnosis?
Retropharyngeal abscess can cause airway obstruction, aspiration and spread into the mediastinum. Children with neck stiffness, dysphagia or fever need prompt imaging, IV antibiotics and surgical review.