Acute bronchitis overview

# Overview
Acute bronchitis is a self-limited lower respiratory tract infection that is more common in young children and the elderly, especially during cold seasons. Viruses, especially influenza, are the most common causative agents. Symptoms include: cough, sputum production and wheezing as well as constitutional symptoms. It must be differentiated from pneumonia, asthma, and GERD. Reassurance and symptomatic medications are mainstays of acute bronchitis. Acute bronchitis may be prevented by hand hygiene, vaccination, and environmental control. Smoking cessation plays a great role in reducing the course of the disease.

# Historical Perspective
Acute bronchitis was first described by Charles Badham in 1808 in England. In 1821, Dr. Rene Laennec, known as the "father of chest medicine," described bronchitis in details.

# Pathophysiology
The causative agent is transmitted through the large and medium size airway tracts and inoculates the tracheobranchial epithelium. This leads to inflammation, thickening, and increased mucus production in the airways. Epithelial-cell desquamation and denuding of the airway to the level of the basement membrane in association with the presence of a lymphocytic cellular infiltrate have been demonstrated on microscopic examination.

# Causes
Common causes of acute bronchitis include viruses, bacteria and environmental factors. Among them, influenza is common.
When bronchitis is prolonged, consider:
- Mycoplasma pneumonia
- Chlamydia pneumoniae
- Bordetella pertussis
Also consider pneumonia and atypical pneumonia.

# Differential Diagnosis of Acute Bronchitis
Acute bronchitis must be differentiated from other diseases that may cause cough, dyspnea, and wheezing including, pneumonia, Asthma Chronic bronchitis, and GERD

# Epidemiology
Acute bronchitis is the ninth most common illness among outpatient visits in the U.S. It's prevalence depends on season of the year, vaccination status and outbreaks during that particular year. It is common among young children and the elderly.

# Risk factors
The main determining risk factors for acute bronchitis are age, season of the year and the immunization status.

# Natural History
If left untreated, acute bronchitis usually resolves within 2 weeks but may last up to 2 months. Prognosis is generally excellent and majority of patients recover after 5-10 days. Recurrent episodes of acute bronchitis in subsequent years occur in 20% of patients.

# Diagnosis
History and symptoms
- Bronchial irritation symptoms including: cough, hoarseness, and phlegm production
- Constitutional symptoms including: Chest pain, Fever, malaise, and Myalgia
Physical examination
- Acute bronchitis presents with signs of prolonged expiration, wheezing, fever and abnormal breath sounds.
Laboratory Tests
- Diagnostic tests are rarely needed to confirm the diagnosis of acute bronchitis. In very specific conditions, serologic tests, viral cultures or sputum analyses may be applied. Generally, inflammatory markers, such as CRP, rise during the course of acute bronchitis. Procalcitonin is helpful to differentiate bacterial from other causes.
Chest x-ray
- Normal lung view is the typical finding on chest x-ray.

# Treatment
Medical therapy
- Reassurance and symptomatic therapy are the mainstay of treatment. NSAIDs, albuterol and antitussives may help alleviate symptoms.
- The most important treatment aspect is to NOT routinely prescribe antibiotics.
- Azithromycin can treat:
Mycoplasma pneumonia
Chlamydia pneumoniae
Bordetella pertussis
- Mycoplasma pneumonia
- Chlamydia pneumoniae
- Bordetella pertussis
Primary prevention
- The major preventive measures for acute bronchitis include: hands hygiene, environmental control, wearing physical barriers, and vaccination for preventable pathogens, such as influenza and pertussis.
Secondary prevention
- Smoking cessation or reduction is helpful in reducing the severity of acute bronchitis symptoms.