Differential Diagnosis for a Patient with a Cough, Productive Phlegm, and Sore Throat

Given the patient's symptoms of a cough for three weeks, productive yellow phlegm, clear lungs, sore throat, and negative Covid and strep throat swabs, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Acute Bronchitis: This is the most likely diagnosis given the patient's symptoms of a persistent cough with productive phlegm and a sore throat, without fever or other systemic symptoms. Acute bronchitis is typically caused by a viral infection and is characterized by inflammation of the bronchial tubes, leading to cough and mucus production.
• Other Likely Diagnoses
  • Allergic Rhinitis: If the patient has allergies, allergic rhinitis could be causing the sore throat and cough due to postnasal drip.
  • Gastroesophageal Reflux Disease (GERD): GERD can cause a chronic cough and sore throat due to acid reflux irritating the throat and respiratory tract.
  • Sinusitis: Although the lungs are clear, sinusitis could be causing the productive cough and sore throat if the sinuses are infected or inflamed.
• Do Not Miss Diagnoses
  • Pertussis (Whooping Cough): Although less common, pertussis can present with a persistent cough and should be considered, especially if the patient is not up to date on vaccinations.
  • Tuberculosis (TB): TB is a critical diagnosis not to miss, as it can present with a chronic cough and requires specific treatment. However, it is less likely without systemic symptoms like fever, weight loss, or exposure history.
  • Lung Cancer: In adult patients, especially those with a history of smoking, lung cancer could be a cause of a persistent cough and should not be missed, although it is less likely without other symptoms like weight loss or hemoptysis.
• Rare Diagnoses
  • Cystic Fibrosis: This genetic disorder can cause chronic respiratory infections and should be considered in patients with recurrent or persistent respiratory symptoms, although it is rare and typically diagnosed in childhood.
  • Bronchiectasis: A condition characterized by damaged airways, leading to chronic cough and mucus production. It is less common and often associated with a history of recurrent infections or specific underlying conditions.

Treatment Approach

The treatment approach will depend on the suspected diagnosis:

• For Acute Bronchitis, treatment is typically supportive, focusing on relieving symptoms with cough suppressants, expectorants, and ensuring adequate hydration.
• For Allergic Rhinitis, GERD, and Sinusitis, treatment involves addressing the underlying condition with antihistamines, acid reducers, or antibiotics for bacterial sinusitis, respectively.
• For Pertussis, TB, and other infectious causes, specific antimicrobial therapy is required.
• For Lung Cancer and other serious conditions, referral to a specialist for further evaluation and treatment is necessary.

Given the negative Covid and strep throat swabs, and in the absence of systemic symptoms, empirical treatment for acute bronchitis or other likely diagnoses may be initiated while further diagnostic workup is considered based on the patient's response to treatment and the presence of any red flag symptoms.