**Question:** Lung abscess is common following ... pneumonia -

A. Streptococcus pneumoniae
B. Haemophilus influenzae
C. Klebsiella pneumoniae
D. Pseudomonas aeruginosa

**Core Concept:** Pneumonia is an infection in the lungs that can lead to complications such as lung abscess. Pneumonia is typically classified into bacterial, viral, or fungal based on the causative organism.

**Why the Correct Answer is Right:**
Lung abscess is more common following bacterial pneumonia, specifically those caused by Gram-negative bacteria. In this case, the correct answer is D. Pseudomonas aeruginosa is a Gram-negative bacterium that can cause severe pneumonia and is associated with a higher risk of developing lung abscess compared to other bacteria mentioned.

**Why Each Wrong Option is Incorrect:**
A. Streptococcus pneumoniae is a common cause of community-acquired pneumonia but is not typically associated with lung abscess due to its Gram-positive nature.
B. Haemophilus influenzae is also a common cause of pneumonia, but it is predominantly associated with pediatric cases and is less likely to cause lung abscess.
C. Klebsiella pneumoniae is a Gram-negative bacterium but is less commonly associated with lung abscess compared to Pseudomonas aeruginosa.

**Clinical Pearl:**
Pneumonia caused by Pseudomonas aeruginosa should be treated with appropriate antibiotics targeting this organism, as it is associated with a higher risk of developing lung abscess compared to other bacteria.

**Correct Answer:** D. Pseudomonas aeruginosa