What is the most likely diagnosis in a patient with a one‑week history of fever, cough, rhinorrhea, epigastric pain, lower abdominal tenderness, no documented temperature, and leukocytosis (white‑blood‑cell count 12 × 10⁹/L)?

Diagnostic Assessment: Community-Acquired Pneumonia with Possible Intra-Abdominal Pathology

Your patient most likely has community-acquired pneumonia (CAP) with concurrent acute gastroenteritis or early acute bacterial rhinosinusitis, requiring immediate chest radiography and empirical antibiotic therapy. 1, 2

Immediate Diagnostic Workup

Obtain an upright PA and lateral chest radiograph immediately because the combination of one-week fever, cough, and rhinorrhea with leukocytosis (WBC 12 × 10⁹/L) meets criteria for suspected CAP, and radiographic confirmation of pulmonary infiltrates is mandatory for diagnosis. 1, 2

The clinical presentation—fever, cough, and rhinorrhea persisting for 7 days—distinguishes this from typical viral upper respiratory infection, which usually resolves within 5 days. 2 Symptoms beyond 5 days with persistent fever suggest either acute bacterial rhinosinusitis or community-acquired pneumonia. 2

Key Clinical Features Supporting Pneumonia

• The leukocytosis (WBC 12 × 10⁹/L) is characteristic of bacterial pneumonia, where elevated white blood cell count, C-reactive protein, and procalcitonin typically occur. 1
• The one-week duration with persistent symptoms makes viral URI unlikely and points toward bacterial infection requiring antibiotic therapy. 2
• Document vital signs immediately: temperature, respiratory rate (watch for ≥30 breaths/minute), oxygen saturation, heart rate, and blood pressure to assess severity. 1, 2

Addressing the Abdominal Findings

The epigastric pain and lower abdominal tenderness create diagnostic complexity, but several considerations apply:

• Epigastric pain can occur in pneumonia as a referred symptom, particularly with lower lobe infiltrates, and does not automatically indicate primary gastrointestinal pathology. 3
• The absence of documented fever in the clinic does not exclude infection—patients often have intermittent fevers, and the patient's report of fever at home is clinically significant. 2
• If abdominal symptoms are prominent, consider obtaining stool studies for bacterial pathogens (Salmonella, Shigella, Campylobacter, C. difficile) and a basic metabolic panel to assess for dehydration or electrolyte abnormalities. 4

Empirical Antibiotic Management

Initiate empirical antibiotic therapy immediately if chest radiograph confirms infiltrates, using amoxicillin-clavulanate 875/125 mg twice daily for 7 days as first-line outpatient therapy. 2 This regimen covers Streptococcus pneumoniae, Haemophilus influenzae, and atypical pathogens.

If the patient appears more ill or has risk factors for complications (tachypnea, hypoxia, multilobar infiltrates), consider hospitalization and broader coverage. 1

Critical Pitfalls to Avoid

• Do not dismiss the diagnosis because temperature was not documented in clinic—patient-reported fever with supporting symptoms and leukocytosis is sufficient to proceed with workup. 2
• Do not attribute all symptoms to gastroenteritis without chest imaging—the respiratory symptoms (cough, rhinorrhea) and leukocytosis mandate pneumonia evaluation. 1, 2
• Do not delay antibiotics waiting for microbiological confirmation—empirical therapy should begin within 6 hours for hospitalized patients or immediately for outpatients with confirmed infiltrates. 1

Follow-Up and Reassessment

• Schedule reassessment within 48-72 hours to ensure clinical improvement on antibiotic therapy. 2
• Instruct the patient to return immediately if dyspnea worsens, confusion develops, or fever persists beyond 72 hours of antibiotics. 2
• If abdominal symptoms worsen or persist, obtain abdominal CT with IV contrast to evaluate for complications such as colitis, abscess, or other intra-abdominal pathology. 4
• If symptoms persist beyond 3 weeks, reclassify as subacute cough and reassess for alternative diagnoses including pertussis, tuberculosis, or post-infectious cough. 3, 2