What is the appropriate investigation and treatment for a 16-year-old female with no significant past medical history, presenting with a frequent cough producing yellow/green sputum and mild fever?

Productive Cough with Fever in an Adolescent Female

Initial Assessment and Red Flag Evaluation

This 16-year-old with frequent cough, yellow/green sputum, and intermittent mild fever requires immediate evaluation for foul-smelling sputum, which would indicate lung abscess or anaerobic infection requiring urgent CT imaging and drainage procedures. 1

Critical Red Flags to Assess Immediately

• Ask specifically about foul-smelling or putrid sputum, as this is pathognomonic for anaerobic lung abscess or necrotizing pneumonia and requires immediate chest CT and broad-spectrum antibiotics plus drainage procedures. 1

• Evaluate for respiratory distress, vital sign abnormalities (tachypnea, tachycardia, hypoxia), hemoptysis, weight loss, or night sweats, as these indicate need for urgent chest X-ray and possible hospitalization. 2

• Assess duration of symptoms carefully: symptoms lasting >2 weeks with persistent fever despite treatment suggest complicated infection (abscess or empyema) rather than simple viral or bacterial bronchitis. 1

Diagnostic Workup Based on Clinical Presentation

If Foul-Smelling Sputum Present

• Obtain chest CT scan immediately (not just chest X-ray), as foul-smelling sputum indicates lung abscess or empyema requiring visualization of cavitary lesions or loculated collections. 1

• Initiate broad-spectrum antibiotics covering anaerobes immediately while awaiting imaging results. 1

• Arrange for percutaneous catheter drainage or surgical consultation if CT demonstrates drainable collection >3 cm, as antibiotics alone will fail. 1

If No Foul Odor But Persistent/Recurrent Pattern

• Chest X-ray is indicated if the patient has abnormal vital signs, abnormal lung examination (crackles, decreased breath sounds, dullness), systemic illness appearance, or high-risk features. 2

• Consider chest X-ray if symptoms persist beyond 2-3 weeks despite appropriate treatment, as this raises concern for underlying structural lung disease (bronchiectasis), tuberculosis in endemic areas, or immunodeficiency. 3, 4

• Screen for immunodeficiency (measure IgG, IgA, IgM levels) if there is a history of recurrent sinopulmonary infections since childhood, as common variable immunodeficiency presents with this pattern. 4

• High-resolution CT scan should be obtained if chest X-ray is normal but symptoms persist beyond 8 weeks or if there is daily production of >30 mL purulent sputum, to evaluate for bronchiectasis. 3, 5

If Acute Presentation (<3 Weeks) with Normal Vital Signs

• Chest X-ray is NOT routinely indicated for acute cough in otherwise healthy patients with normal physical examination, normal oxygen saturation, and no signs of bacterial pneumonia. 6, 2

• The presence of yellow/green sputum does NOT indicate bacterial infection, as colored sputum simply reflects inflammatory cells and debris from viral infection and has poor predictive value for bacterial infection (positive likelihood ratio only 1.46). 6, 7

Treatment Algorithm

For Presumed Viral or Post-Viral Cough (Most Likely Scenario)

• First-line symptomatic treatment includes: first-generation antihistamine plus decongestant combination (if postnasal drip suspected), naproxen (which may favorably affect cough), honey for cough suppression, and adequate hydration. 6, 2

• Dextromethorphan 60 mg has been shown to suppress acute cough in meta-analysis and can be used for symptomatic relief. 6

• Antibiotics should NOT be prescribed for colored sputum alone, as this contributes to resistance without clinical benefit when bacterial pneumonia is not present. 6, 7

For Confirmed or Suspected Bacterial Pneumonia

• Empiric antibiotics are indicated only if there is clinical evidence of pneumonia: abnormal vital signs, focal consolidation on examination, or radiographic infiltrate. 3, 2

• For outpatient community-acquired pneumonia in adolescents, appropriate regimens include respiratory fluoroquinolones or macrolides covering Streptococcus pneumoniae, Mycoplasma pneumoniae, and Chlamydia pneumoniae. 3

For Chronic/Recurrent Pattern Suggesting Underlying Disease

• If bronchiectasis is diagnosed on HRCT, treatment includes airway clearance techniques, treatment of acute exacerbations with antibiotics targeting Haemophilus influenzae, Staphylococcus aureus, Streptococcus pneumoniae, and Pseudomonas aeruginosa, and evaluation for underlying causes (cystic fibrosis, immunodeficiency, allergic bronchopulmonary aspergillosis). 3

• If common variable immunodeficiency is diagnosed, initiate intravenous immunoglobulin replacement therapy, typically on a three-week regimen to prevent breakthrough infections. 4

Follow-Up and Safety Net Instructions

• Return immediately or call if: breathing difficulty develops, foul-smelling sputum appears, hemoptysis occurs, or fever persists beyond 3-5 days of appropriate treatment. 1, 2

• Schedule follow-up if: cough persists beyond 3 weeks despite treatment, as this transitions to subacute cough requiring systematic evaluation for postnasal drip syndrome, asthma, or gastroesophageal reflux disease. 3, 6

• Cough persisting beyond 8 weeks meets criteria for chronic cough and requires comprehensive evaluation using the anatomic diagnostic protocol, as the cause can be determined in >95% of cases. 3, 8, 5

Critical Pitfalls to Avoid

• Do not prescribe antibiotics based solely on sputum color, as this has poor diagnostic accuracy and promotes resistance. 6, 7

• Do not delay CT imaging if foul-smelling sputum is present, as chest X-ray alone has poor positive predictive value for identifying lung abscess or empyema. 1

• Do not treat with antibiotics alone if imaging shows a drainable collection >3 cm, as this will fail and delay definitive drainage therapy. 1

• Do not miss the diagnosis of immunodeficiency in patients with recurrent sinopulmonary infections since childhood, as early diagnosis prevents significant morbidity. 4