Causes of Acute Tracheobronchitis

Respiratory viruses are the most common cause of acute tracheobronchitis, accounting for approximately 90% of all cases. 1

Viral Causes

Influenza viruses (A and B) are major causative agents, particularly associated with more severe symptoms including cough (93%), fever (68%), and myalgia (94%) 1
Parainfluenza viruses, especially parainfluenza 3, are commonly identified in patients with acute tracheobronchitis 1, 2
Respiratory syncytial virus (RSV) is a substantial cause, particularly in the elderly and households with small children, with attack rates as high as 61.2-75% in outbreaks 1
Coronaviruses, including the SARS-associated coronavirus, can cause acute tracheobronchitis symptoms 1
Adenoviruses and rhinoviruses more commonly produce upper respiratory tract symptoms but can also cause acute tracheobronchitis 1

Only three bacteria have been definitively established as nonviral causes of uncomplicated acute tracheobronchitis in adults without underlying lung disease 1:
- Bordetella pertussis
- Mycoplasma pneumoniae
- Chlamydia pneumoniae (TWAR)
These bacterial agents collectively account for only 5-10% of acute tracheobronchitis cases 1
In patients with chronic bronchitis experiencing an acute exacerbation, bacterial superinfection may occur with organisms such as Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae 1
Rare cases of fungal tracheobronchitis (Aspergillus species) can occur in severely immunocompromised patients 3, 4
Unusual bacterial causes like Aeromonas veronii have been reported in specific circumstances such as near-drowning 5

Occult asthma exacerbation can present with symptoms similar to acute tracheobronchitis 1
Toxic fume inhalation can trigger inflammatory responses in the tracheobronchial tree 1

Highest incidence occurs during winter months, similar to pneumonia and bronchiolitis 2
In school-aged children, tracheobronchitis tends to peak in late winter or early spring, often coinciding with influenza B outbreaks 2
Viral respiratory infections can predispose airways to bacterial superinfection by 1:
- Interfering with mucociliary clearance
- Impairing bacterial killing by pulmonary macrophages
- Increasing the risk of aspirating secretions containing bacteria from upper airways

Diagnosis of acute tracheobronchitis should be made only after excluding pneumonia, common cold, acute asthma, or COPD exacerbation 1
The pathogen responsible for acute tracheobronchitis is rarely identified in clinical practice because viral cultures and serologic assays are not routinely performed 1
Even in prospective studies, a causative organism is identified in only 16-40% of cases 1
Gram stain and culture of sputum do not reliably detect M. pneumoniae, C. pneumoniae, or B. pertussis, making these tests generally not recommended in uncomplicated acute bronchitis 1

In patients with chronic bronchitis, acute exacerbations are often preceded by upper respiratory tract infections and characterized by increased sputum volume, purulence, and/or worsening shortness of breath 1
Immunocompromised patients, particularly those with hematological malignancies, are at risk for unusual pathogens like invasive Aspergillus causing necrotizing tracheobronchitis 3, 4