Bronchitis, Acute

Descriptive text is not available for this image Basics

  • Acute bronchitis is defined as an acute, self-limited inflammation of the tracheobronchial tree, most commonly caused by viral infections. It presents with a cough (with or without sputum production) lasting <3 weeks in individuals without chronic pulmonary disease. Importantly, acute bronchitis occurs in the absence of pneumonia, as confirmed by lack of radiographic evidence, and should not be confused with exacerbations of chronic lung conditions like chronic obstructive pulmonary disease (COPD) or asthma.
  • It is primarily a clinical diagnosis, and in the absence of pneumonia or other underlying lung disease, it does not require routine antibiotic therapy.

Description

  • Acute bronchitis is a lower respiratory tract infection that causes reversible bronchial inflammation, involving the large airways, without evidence of pneumonia, that occurs in the absence of chronic obstructive lung disease.
  • Cough, the predominant symptom, may last as long as 3 weeks.
  • Generally self-limited, with complete healing and full return of function
  • Most infections are viral if no underlying cardiopulmonary disease is present.
  • Synonym(s): tracheobronchitis
  • Geriatric patients:
    • More severe illness may occur in those with underlying heart or lung disease (e.g., congestive heart failure (CHF), COPD), especially if caused by influenza.
    • Monitor closely for secondary infections or decompensation.
  • Pediatric patients:
    • Often associated with viral upper and lower respiratory infections
    • Recurrent episodes warrant evaluation for asthma, anatomic airway anomalies, or immunodeficiency.
    • Respiratory syncytial virus (RSV) may cause severe or fatal outcomes in infants, especially with prematurity or chronic lung disease.

Epidemiology

Incidence

  • Acute bronchitis is one of the most common diagnoses in primary care settings, with approximately 5% of adults and 6–10% of children being affected annually (1),(2).
  • The condition is most prevalent during the fall and winter months, corresponding with the peak season for viral respiratory infections like influenza, rhinovirus, and RSV.
  • Age distribution:
    • Adults: Acute bronchitis is more common in younger adults and those with lower socioeconomic status or underlying respiratory conditions such as asthma or COPD.
    • Children: Acute bronchitis is frequent among preschool-aged children, who are more susceptible to viral respiratory infections. In children, the condition is often associated with other upper and lower respiratory infections, such as the common cold or RSV.

Etiology and Pathophysiology

  • Primary causes:
    • Viral infections (90%+ of cases):
      • Common viruses include rhinovirus, influenza, parainfluenza, RSV, adenovirus, and coronavirus.
    • Bacterial infections (less common):
      • Includes Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis, Streptococcus pneumoniae, and Haemophilus influenzae
      • Typically seen in secondary infections or specific populations (e.g., immunocompromised)
    • Environmental and underlying conditions: Tobacco exposure, air pollution, or preexisting lung diseases (COPD, asthma) increase susceptibility.
  • Pathophysiology of acute bronchitis
    • Viral inflammation:
      • Infection leads to bronchial epithelial inflammation with edema and mucus hypersecretion.
      • Viral damage impairs ciliary function, reducing mucus clearance.
    • Immune response:
      • T lymphocytes, neutrophils, and macrophages are recruited to the airway to fight infection.
      • Pro-inflammatory cytokines (e.g., IL-6, TNF-α) contribute to symptoms (e.g., cough, wheezing).
    • Mucus hypersecretion: Goblet cells produce excessive mucus, leading to viscous sputum and contributing to productive cough; can cause bronchial obstruction and wheezing.
    • Bronchospasm and airway narrowing: In patients with reactive airway disease, infection may trigger bronchospasm, resulting in dyspnea and chest tightness.

Genetics

No known genetic pattern

Risk Factors

  • Infants
  • Elderly
  • Air pollutants
  • Smoking
  • Secondhand smoke
  • Environmental changes
  • Chronic bronchopulmonary diseases
  • Chronic sinusitis
  • Tracheostomy or endobronchial intubation
  • Bronchopulmonary allergy
  • Hypertrophied tonsils and adenoids in children
  • Immunosuppression
    • Immunoglobulin deficiency
    • HIV infection
    • Alcoholism
  • Gastroesophageal reflux disease (GERD)

General Prevention

  • Avoid smoking and secondhand smoke.
  • Control underlying risk factors (i.e., asthma, sinusitis, and reflux).
  • Avoid exposure, especially daycare.
  • Pneumovax, influenza immunization

Commonly Associated Conditions

  • COPD
  • Asthma
  • CHF
  • Cystic fibrosis
  • Diabetes
  • GERD
  • Immunocompromised states (e.g., HIV, organ transplant, chemotherapy)
  • Recent upper respiratory infections (e.g., common cold, influenza)
  • Sinusitis or rhinitis
  • Allergic rhinitis

There's more to see -- the rest of this topic is available only to subscribers.