**Core Concept**
Hemorrhagic external otitis media, also known as perichondritis or necrotizing external otitis, is a rare but severe infection of the external ear cartilage and surrounding tissues. This condition is characterized by inflammation, necrosis, and bleeding in the affected area.

**Why the Correct Answer is Right**
The correct answer is **Pseudomonas aeruginosa**, an opportunistic gram-negative bacterium that commonly infects individuals with compromised immune systems, such as those with diabetes, HIV/AIDS, or undergoing chemotherapy. Pseudomonas aeruginosa produces virulence factors that facilitate its colonization and invasion of the external ear canal, leading to the characteristic symptoms of hemorrhagic external otitis media. The bacterium's ability to form biofilms and resist antimicrobial agents contributes to the severity of the infection.

**Why Each Wrong Option is Incorrect**
**Option A:** Staphylococcus aureus is a common cause of skin and soft tissue infections but is not typically associated with hemorrhagic external otitis media.
**Option B:** Streptococcus pneumoniae is a common cause of otitis media but does not typically cause hemorrhagic external otitis media.
**Option C:** Haemophilus influenzae is a common cause of otitis media and sinusitis but is not typically associated with hemorrhagic external otitis media.

**Clinical Pearl / High-Yield Fact**
Hemorrhagic external otitis media is a medical emergency that requires prompt treatment with intravenous antibiotics, such as ceftazidime or ciprofloxacin, and supportive care to prevent complications, including cartilage destruction and hearing loss.

**Correct Answer: D. Pseudomonas aeruginosa**