Acute bronchitis
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Acute Bronchitis: Diagnosis, Causes, and Treatment
Overview of Acute Bronchitis
Definition and Symptoms
Acute bronchitis is a common lower respiratory tract infection characterized by reversible bronchial inflammation. It typically presents with a cough, which may or may not be productive of phlegm, and lasts for up to three weeks . Other symptoms can include wheezing, shortness of breath, and chest discomfort.
Epidemiology
Acute bronchitis is a frequent reason for medical consultations, particularly in the United States, where it accounts for millions of office visits annually . It is most commonly diagnosed in otherwise healthy adults and is often mistaken for other respiratory conditions such as the common cold, asthma, or pneumonia .
Etiology of Acute Bronchitis
Viral Causes
The majority of acute bronchitis cases are caused by viral infections, with respiratory viruses such as influenza, parainfluenza, respiratory syncytial virus (RSV), coronavirus, adenovirus, and rhinoviruses being the most common culprits . These viruses primarily affect the lower respiratory tract but can also cause upper respiratory symptoms.
Bacterial Causes
Bacterial infections are less common, accounting for fewer than 10% of acute bronchitis cases. The primary bacterial pathogens include Bordetella pertussis, Mycoplasma pneumoniae, and Chlamydia pneumoniae . There is no substantial evidence that typical bacteria like Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis cause acute bronchitis in individuals without underlying lung disease .
Diagnosis of Acute Bronchitis
Clinical Assessment
Diagnosis is primarily clinical, based on the presence of a persistent cough and the exclusion of other conditions such as pneumonia, asthma, or chronic obstructive pulmonary disease (COPD) exacerbations . A normal chest radiograph is a key diagnostic criterion to rule out pneumonia .
Investigations
Routine investigations, including viral cultures and serologic assays, are not typically performed due to their limited impact on management . In cases where the cough persists beyond three weeks, further evaluation may be necessary to rule out other causes .
Treatment of Acute Bronchitis
Antibiotic Use
Despite the viral etiology in most cases, antibiotics are frequently prescribed, although evidence suggests they offer little benefit in terms of symptom relief or illness duration . Overuse of antibiotics is discouraged to prevent antibiotic resistance .
Symptomatic Relief
Treatment is mainly supportive. Antitussive agents can be used for short-term relief of cough, but there is no strong evidence supporting the use of inhaled bronchodilators or expectorants . In cases of confirmed or probable whooping cough, a macrolide antibiotic is recommended to reduce coughing paroxysms and prevent disease spread.
Non-Pharmacological Measures
Patients are advised to rest, stay hydrated, and use humidifiers to ease symptoms. Education on the natural course of the illness and setting realistic expectations for recovery are crucial for patient satisfaction.
Conclusion
Acute bronchitis is a self-limited respiratory condition predominantly caused by viral infections. Accurate diagnosis involves ruling out other serious conditions, and treatment focuses on symptomatic relief rather than antibiotics. Efforts to reduce unnecessary antibiotic use are essential to combat antibiotic resistance. If symptoms persist beyond three weeks, further investigation is warranted to identify other potential causes.
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