Bronchitis - Uncomplicated Acute Differential Diagnosis

Differential Diagnosis

Pertussis is an uncommon cause of uncomplicated acute bronchitis, but it may be present in up to 10–20% of adults with cough lasting more than 2–3 weeks. Adults who were immunized as children but no longer have effective immunity may serve as a reservoir of B pertussis. Although there are no classic features of pertussis in adults as there are in children, it generally presents as severe bronchitis. Pertussis may be considered in children suffering from severe spasmodic coughing, especially if the episode is terminated by vomiting or is associated with redness of the face and catching of breath. The incidence of pertussis in children has decreased due to widespread pertussis vaccination. Physicians should limit suspicion and treatment of adult pertussis to patients with a high probability of exposure, such as during an outbreak in the community or if there is a history of contact with a patient who has a known case. If pertussis is suspected, a diagnostic test may be performed, and antimicrobial therapy may be initiated. Diagnosis may be difficult to establish due to delay in suspicion of disease, as cultures of nasopharyngeal secretions are usually negative after 2 weeks, and reliable serologic tests may not be available. Polymerase chain reaction (PCR) of nasopharyngeal swabs or aspirates improves detection.    

Asthma should be considered in patients with repetitive episodes of acute bronchitis. Full spirometric testing with bronchodilatation or provocative testing with a Methacholine challenge test can be given to help differentiate asthma from recurrent bronchitis. Acute bronchitis may cause transient pulmonary abnormalities, and the diagnosis of asthma should be considered if abnormalities in pulmonary function persist after the acute phase of the illness.  

Please see Asthma disease management chart for further information.  

Flu viruses are the most common pathogens found in patients with uncomplicated acute bronchitis. During times of outbreak, diagnosis by clinical presentation is as accurate as rapid diagnostic tests. The patient may benefit from anti-influenza agents if treated within 48 hours of symptom onset.  

Please see Influenza disease management chart for further information.  

Pneumonia is potentially the most serious cause of acute cough illness and should be ruled out. In healthy non-elderly adults, the absence of vital sign abnormalities such as heart rate ≥100 beats per minute, respiratory rate >24 breaths per minute, oral temperature ≥38°C, and signs of focal consolidation on chest exam, sufficiently reduces the likelihood of pneumonia and eliminates the need for a chest X-ray.  

Please see Pneumonia – Community-Acquired disease management chart for further information.  

Coronavirus disease 2019 (COVID-19) may present as an acute upper or LRTI. Testing for COVID-19 is indicated for patients with prolonged cough or when pneumonia is suspected.  

Please see Coronavirus Disease 2019 (COVID-19) disease management chart for further information.  

In upper respiratory tract infections (URTI), cough is not a predominant symptom, as seen in conditions such as the common cold. Non-pulmonary causes of cough may include chronic heart failure in elderly patients, gastroesophageal reflux disease, and bronchogenic tumor.  

Please see Heart Failure – Chronic and Gastroesophageal Reflux Disease disease management charts for further information.