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Summary Table

Category	Details
Risk Factors	Age 6 months to 8 years (peak 3 to 5 years); recent viral upper respiratory infection, particularly viral croup; autumn/winter seasonality; immunocompromised state
Etiology	Secondary bacterial superinfection of the tracheal mucosa, most commonly Staphylococcus aureus; also Moraxella catarrhalis, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae
Patient Presentation	Child who initially had croup-like illness that suddenly worsens over 2 to 7 days with high fever, toxic appearance, and stridor unresponsive to nebulized epinephrine
Classic Physical Exam	High fever (often >39C), toxic-appearing child, barking cough, biphasic stridor, respiratory distress; notably no drooling and no dysphagia; child can lie flat
Key Diagnostic Results	Lateral neck radiograph: subglottic narrowing with irregular tracheal mucosa ("shaggy" or "ragged" tracheal wall); elevated WBC with left shift; direct laryngoscopy reveals pseudomembranes and purulent secretions
Management	Airway stabilization (intubation if needed), IV anti-staphylococcal antibiotics (vancomycin or ampicillin-sulbactam), tracheal suctioning, ICU monitoring
Keywords	"Croup not responding to treatment," "high fever with stridor," "toxic-appearing child with barking cough," "membranous croup," "pseudomembranes in trachea," "ragged tracheal wall on X-ray"

1. Pathophysiology

Bacterial tracheitis, also called membranous croup or pseudomembranous croup, is an acute bacterial infection of the subglottic trachea. The disease almost always develops as a secondary bacterial superinfection following a primary viral upper respiratory tract infection, most commonly parainfluenza virus (the same pathogen that causes viral croup). The preceding viral illness damages the tracheal mucosal epithelium, disrupts the normal mucociliary clearance mechanism, and creates an environment conducive to bacterial colonization.

Once bacteria (most frequently Staphylococcus aureus) invade the damaged mucosa, a vigorous inflammatory response ensues. The hallmark pathological finding is the formation of pseudomembranes, which are thick, adherent layers composed of fibrin, inflammatory exudate, necrotic epithelial debris, and bacterial colonies lining the tracheal wall. These pseudomembranes, combined with copious thick purulent secretions, progressively narrow the already small pediatric airway.

This is why the patient initially looks like viral croup but then acutely decompensates. The viral phase produces the classic barking cough and stridor due to subglottic edema. However, when bacterial superinfection takes hold, the child develops high-grade fever and a toxic appearance that is disproportionate to what would be expected in simple croup. The stridor worsens and, critically, does not improve with nebulized racemic epinephrine or corticosteroids, because the obstruction is not primarily from edema but from thick secretions and pseudomembranes physically occluding the airway.

The reason this condition is dangerous lies in the mechanical nature of the obstruction. Unlike croup, where edema can be pharmacologically reduced, the pseudomembranes and tenacious secretions cannot be reversed with medications alone. Fragments of pseudomembrane can also dislodge and cause acute, complete airway obstruction, making this a true airway emergency requiring intervention.

2. Classification and Clinical Manifestation

Bacterial tracheitis does not have a formal classification system. However, the clinical course can be divided into phases that are important for exam recognition:

Phase	Timing	Clinical Features
Prodromal (Viral) Phase	Day 1 to 3	Rhinorrhea, low-grade fever, mild barking cough, mild stridor; clinically indistinguishable from viral croup; responds to standard croup management
Acute Bacterial Phase	Day 2 to 7 after viral onset	Sudden clinical deterioration; high fever (>39C), toxic appearance, worsening stridor (often biphasic), increased work of breathing; failure to respond to nebulized epinephrine and dexamethasone
Critical/Obstructive Phase	Hours after bacterial onset	Severe respiratory distress, cyanosis, drooling (late sign from inability to handle secretions, not odynophagia), impending respiratory failure; may require emergent intubation

Clinical Manifestation

feature	description
Cough	Barking, brassy, and productive of thick purulent sputum
Stridor	Initially inspiratory (subglottic), progresses to biphasic as obstruction worsens
Fever	High-grade, distinguishing it from simple viral croup
Appearance	Toxic, ill-appearing; in contrast to croup where the child appears relatively well between coughing episodes
Positional Preference	Can lie flat (unlike epiglottitis where the child prefers to sit upright in the "tripod" or "sniffing" position)
Swallowing	Intact; no true dysphagia or drooling early on (unlike epiglottitis)

3. Diagnostic Workup

Test	Role	Expected Finding
Lateral and AP neck radiograph	Best initial test	AP view: steeple sign (subglottic narrowing, similar to croup); Lateral view: irregular, ragged tracheal margins with intraluminal opacities (pseudomembranes); subglottic haziness; distended hypopharynx
Direct laryngoscopy / bronchoscopy	Most accurate (confirmatory) test	Visualization of pseudomembranes, purulent exudates, and erythematous, edematous tracheal mucosa; allows suctioning and specimen collection
CBC with differential	Supportive	Leukocytosis with left shift (bandemia)
Blood cultures	Supportive	Often negative; positive in a minority of cases
Tracheal aspirate culture	Identifies causative organism	Typically grows S. aureus; guides targeted antibiotic therapy

The best initial test is a lateral neck radiograph. The test writer places this as the correct answer because it is noninvasive and can be performed rapidly. The classic finding is an irregular or "shaggy" tracheal contour on the lateral view, which represents pseudomembranes and mucosal irregularity projecting into the airway lumen. This is the key radiographic discriminator from viral croup, where the tracheal wall appears smooth even though both conditions share subglottic narrowing (steeple sign) on the AP view.

Other radiographic clues include a distended hypopharynx (from air trapping above the obstruction) and intraluminal soft tissue densities within the trachea, representing detached pseudomembrane fragments.

The most accurate test is direct laryngoscopy or bronchoscopy, which confirms the diagnosis by directly visualizing the pseudomembranes and purulent secretions adherent to the tracheal mucosa. This also serves a therapeutic purpose, as it allows suctioning of secretions and debridement of pseudomembranes to relieve obstruction. In practice, this is performed in a controlled setting (operating room or ICU) with preparation for potential intubation.

Laboratory studies are supportive but not diagnostic. The CBC typically shows leukocytosis with a left shift, consistent with bacterial infection. Blood cultures are obtained but are frequently negative (positive in roughly 10% of cases). Tracheal aspirate cultures obtained during laryngoscopy are the most reliable method for identifying the causative organism and guiding antibiotic therapy.

A point to note for exam purposes: the lateral neck X-ray in epiglottitis shows a thumbprint sign (swollen epiglottis), while in bacterial tracheitis the epiglottis appears normal and the pathology is at the subglottic/tracheal level.

4. Management and Treatment

Step	Intervention	Details
Airway stabilization	Assessment and preparation for intubation	Most patients (up to 80%) require intubation; use an endotracheal tube 0.5 to 1.0 size smaller than age-predicted due to tracheal swelling; have tracheostomy tray available
Tracheal suctioning	Frequent suctioning via ETT or bronchoscopy	Removal of pseudomembranes and thick secretions; critical for maintaining airway patency
IV antibiotics	Empiric anti-staphylococcal coverage	First-line: vancomycin 15 mg/kg IV every 6 hours (to cover MRSA) PLUS a third-generation cephalosporin (e.g., ceftriaxone 50 to 100 mg/kg/day IV); alternative: ampicillin-sulbactam 50 mg/kg IV every 6 hours if MRSA prevalence is low
Supportive care	ICU admission, humidified oxygen, IV fluids	Monitor for acute airway decompensation; keep NPO if intubation is anticipated
Duration	10 to 14 days of antibiotics	Narrow based on tracheal aspirate culture and sensitivity results

The first priority is securing the airway. Unlike viral croup, where nebulized racemic epinephrine and systemic corticosteroids are effective, these interventions do not provide meaningful relief in bacterial tracheitis because the obstruction is caused by pseudomembranes and purulent secretions rather than mucosal edema alone. The failure of standard croup management is itself a diagnostic clue.

A large proportion of children with bacterial tracheitis require endotracheal intubation for airway protection. A key exam-testable detail: use an endotracheal tube 0.5 to 1.0 mm smaller than the age-calculated size to accommodate the tracheal swelling and avoid further mucosal trauma. Once intubated, frequent tracheal suctioning is essential to clear the thick secretions and pseudomembrane fragments that can occlude even an artificial airway.

Empiric IV antibiotics should cover the most common pathogen, Staphylococcus aureus, including MRSA. The standard regimen is vancomycin combined with a third-generation cephalosporin (such as ceftriaxone) to provide broad coverage against other organisms like H. influenzae, S. pneumoniae, and M. catarrhalis. Once culture and sensitivity data return from the tracheal aspirate, the regimen is narrowed accordingly.

Corticosteroids are generally not considered the primary treatment, though some clinicians use them adjunctively. The test answer will not list steroids as the correct management for bacterial tracheitis; this is a deliberate contrast with viral croup where dexamethasone is first-line.

Patients should be admitted to an ICU given the risk of sudden airway compromise. The typical antibiotic course is 10 to 14 days, with transition to oral antibiotics when the child is clinically improving, afebrile, and extubated. Most children improve within 3 to 7 days with appropriate treatment, and mortality with modern management is low.

5. Differential Diagnosis and Distractors

Differential	Why It Is Similar	Key Discriminator
Viral croup (laryngotracheobronchitis)	Barking cough, stridor, steeple sign on AP neck X-ray, same age group	Croup presents with low-grade or no fever, child appears non-toxic, and symptoms respond to nebulized epinephrine and dexamethasone; lateral neck X-ray shows smooth subglottic narrowing without tracheal irregularity
Epiglottitis	Acute-onset stridor, high fever, toxic appearance, upper airway obstruction	Epiglottitis presents with drooling, dysphagia, muffled ("hot potato") voice, and the child prefers the tripod/sniffing position; lateral neck X-ray shows thumbprint sign (swollen epiglottis); no barking cough; the trachea is normal
Retropharyngeal abscess	High fever, toxic child, stridor, neck imaging abnormalities	Presents with neck stiffness, refusal to extend the neck, bulging posterior pharyngeal wall on exam; lateral neck X-ray shows widened prevertebral soft tissue (>7 mm at C2 or >14 mm at C6 in children); CT with contrast shows rim-enhancing fluid collection
Foreign body aspiration	Sudden-onset stridor and respiratory distress in a toddler	No preceding viral prodrome, no fever; onset is abrupt during eating or playing; unilateral decreased breath sounds and wheezing; chest X-ray may show unilateral hyperinflation or visible radiopaque object; inspiratory/expiratory films show air trapping
Peritonsillar abscess	Fever, sore throat, "hot potato" voice in older children	Presents with trismus (inability to open mouth), uvular deviation, and unilateral tonsillar swelling; typically affects adolescents/young adults, not the toddler age group
Diphtheria	Pseudomembrane formation in the airway, stridor, toxic appearance	Thick, grayish-white membrane over the pharynx and tonsils (not confined to the trachea); bull neck from cervical lymphadenopathy; history of incomplete immunization; culture grows Corynebacterium diphtheriae

6. Traps and High-Yield Pearls

The most common way students get questions on bacterial tracheitis wrong is by confusing it with either viral croup or epiglottitis. The test writer constructs the vignette to have an initial presentation that looks exactly like croup, then introduces a clinical pivot: the child suddenly worsens, develops a high fever, appears toxic, and fails to improve with nebulized epinephrine. Students who do not recognize this biphasic clinical course (viral prodrome followed by acute bacterial deterioration) will incorrectly select croup as the answer and choose nebulized epinephrine as the next step, which is the trap.

The second common error is selecting epiglottitis. Both conditions present with high fever, stridor, and a toxic-appearing child. The discriminator is that epiglottitis features drooling, dysphagia, and absence of a barking cough, while bacterial tracheitis features a barking cough, no drooling, no dysphagia, and the ability to lie flat. On imaging, epiglottitis shows the thumbprint sign, while bacterial tracheitis shows a normal epiglottis with an irregular, ragged tracheal wall.

A third trap involves management. Students may select dexamethasone as the treatment, carrying over the reflex from croup management. The correct answer is IV antibiotics with anti-staphylococcal coverage and airway management, not steroids.

The core competency being tested is the ability to recognize that a child with croup who acutely worsens and fails standard therapy has progressed to bacterial tracheitis, and that the management shifts from pharmacologic airway management (epinephrine and steroids) to antibiotics, suctioning, and intubation preparedness. This tests the student's understanding of a clinical escalation pattern and the distinction between obstructive pathologies driven by edema versus those driven by purulent secretions and pseudomembranes.

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