**Core Concept**
Pneumatoceles are air-filled cavities within the lung parenchyma, often seen in children with severe pneumonia, particularly due to Staphylococcus aureus infection. The formation of pneumatoceles is a result of the lung's attempt to contain the infection, leading to the creation of these cavities.

**Why the Correct Answer is Right**
In the context of Staphylococcus aureus pneumonia, pneumatoceles form due to the production of **coagulase**, an enzyme that facilitates the breakdown of fibrinogen to fibrin, leading to a localized area of necrosis within the lung tissue. This process creates a cavity filled with air, which can be seen on chest radiograms. The formation of pneumatoceles is a hallmark of severe Staphylococcus aureus pneumonia in children.

**Why Each Wrong Option is Incorrect**
**Option A:** While Haemophilus influenzae can cause pneumonia in children, it is not typically associated with the formation of pneumatoceles. **Option B:** Streptococcus pneumoniae can cause pneumonia, but it is not characteristically linked to pneumatoceles. **Option C:** Klebsiella pneumoniae can cause severe pneumonia, but pneumatoceles are not a typical feature of this infection.

**Clinical Pearl / High-Yield Fact**
Pneumatoceles are a classic radiographic finding in Staphylococcus aureus pneumonia, particularly in children. It is essential to consider this diagnosis in children presenting with severe pneumonia and pneumatoceles on chest radiograms.

**Correct Answer:** D. Staphylococcus aureus