Which organism is the classic bug for lobar pneumonia?

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Multiple Choice

Which organism is the classic bug for lobar pneumonia?

Lobar pneumonia is classically caused by Streptococcus pneumoniae. This gram-positive, alpha-hemolytic diplococcus is optochin sensitive and bile soluble, and it tends to produce a dense, homogeneous consolidation of one lobe. On chest imaging, this appears as a single-lobe opacity with air-filled bronchi visible (air bronchograms). Clinically, it often presents with sudden onset fever, productive cough (sometimes with rusty sputum), and pleuritic chest pain. Because of its classic presentation and radiographic pattern, pneumococcus remains the prototypical cause of community-acquired lobar pneumonia. Other organisms tend to produce different patterns: Staphylococcus aureus more commonly follows influenza and produces patchy, multilobar infiltrates or abscesses rather than a single-lobe consolidation. Haemophilus influenzae is often seen in patients with chronic lung disease and tends to cause bronchopneumonia patterns. Pseudomonas aeruginosa is usually linked to hospital- or ventilator-associated pneumonia and in certain at-risk populations, not the classic lobar pattern.

Lobar pneumonia is classically caused by Streptococcus pneumoniae. This gram-positive, alpha-hemolytic diplococcus is optochin sensitive and bile soluble, and it tends to produce a dense, homogeneous consolidation of one lobe. On chest imaging, this appears as a single-lobe opacity with air-filled bronchi visible (air bronchograms). Clinically, it often presents with sudden onset fever, productive cough (sometimes with rusty sputum), and pleuritic chest pain. Because of its classic presentation and radiographic pattern, pneumococcus remains the prototypical cause of community-acquired lobar pneumonia.

Other organisms tend to produce different patterns: Staphylococcus aureus more commonly follows influenza and produces patchy, multilobar infiltrates or abscesses rather than a single-lobe consolidation. Haemophilus influenzae is often seen in patients with chronic lung disease and tends to cause bronchopneumonia patterns. Pseudomonas aeruginosa is usually linked to hospital- or ventilator-associated pneumonia and in certain at-risk populations, not the classic lobar pattern.

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