Differential Diagnosis
Angiotensin Converting Enzyme (ACE) Inhibitor Use
Treatment with ACE inhibitors may produce a non-productive cough
in up to 15% of patients.
Asthma
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.
Coronavirus Disease 2019 (COVID-19)
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.
Influenza (Flu)
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.
Lung Cancer
Lung cancer is an uncommon cause of acute
cough but should be considered in current or previous smokers.
Non-pulmonary Causes
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.
Pertussis
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.
Pneumonia
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.
Upper Respiratory Tract Infection (URTI)
In URTI, cough is not a predominant symptom, as seen in
conditions such as the common cold.