🔍 Question

A 62-year-old man with a medical history of chronic bronchitis, type II diabetes, and hypertension comes to the emergency department with worsening shortness of breath and cough. He mentions difficulty speaking due to his breathing issues and reports an increase in sputum production compared to his baseline. He recalls experiencing nasal congestion and facial discomfort last week, which he attributed to allergies and did not seek medical attention. He denies fever, chills, sore throat, chest pain, or recent exposure to illness.

On examination, his temperature is 37.9°C (100.2°F), respiratory rate is 22 breaths/min, heart rate is 99 bpm, blood pressure is 140/86 mmHg, and oxygen saturation is 85% on room air. The physical exam reveals tenderness over the frontal and maxillary sinuses. The lungs exhibit decreased breath sounds and dullness to percussion over the left lower lobe. Other findings, including the cardiac exam, abdominal exam, and extremity pulses, are unremarkable. A sputum culture identifies a Gram-positive diplococcus. The patient is started on supplemental oxygen and empiric antibiotics before being admitted for further care.

Which of the following organisms is the most likely cause of this patient’s condition?

A. Haemophilus influenzae

B. Klebsiella pneumoniae

C. Moraxella catarrhalis

D. Staphylococcus aureus

E. Streptococcus pneumoniae

Correct Answer 🎯: E. Streptococcus pneumonia

⚙️

Initial Infection

Facial pain, nasal congestion 🧠

⬇

Sinusitis (preceding viral/bacterial infection) → Sinus pathogens multiply.

Secondary Infection

Sinusitis pathogens enter lower respiratory tract 🧠

⬇

Weak host defense (chronic bronchitis, diabetes) → ↓ Mucociliary clearance.

⬇

Bacterial colonization (e.g., Streptococcus pneumoniae).

Pulmonary Effects

Streptococcus pneumoniae colonization → Capsule evades phagocytosis 🧠

⬇

↑ Local inflammation (cytokines, neutrophil recruitment).

⬇

Lobar consolidation → ↓ Alveolar gas exchange.

⬇

Hypoxemia (O2 sat ⬇ to 85%).

⬇

Shortness of breath, labored breathing.Systemic Effects

Inflammatory cytokines → Fever (37.9°C).

⬇

↑ Energy demand + metabolic stress → Worsens diabetes control.

Diagnostic Clue:

• Diplococcus staining purple → Gram-positive organism.

• Most common in community-acquired pneumonia → Streptococcus pneumoniae.

⚖️ Explanation of Other Differentials

📝 Flashcards

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Dr. Shoaib Ahmad

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