Malignant otitis externa is due to?
**Core Concept**
Malignant otitis externa, also known as necrotizing otitis externa, is a severe infection of the external auditory canal that can spread to surrounding tissues and bones. This condition is characterized by its aggressive progression and potential for serious complications.
**Why the Correct Answer is Right**
Malignant otitis externa is typically caused by Pseudomonas aeruginosa, an opportunistic gram-negative bacteria. This bacterium thrives in moist environments and can cause significant tissue damage due to its ability to produce virulence factors such as exotoxin A and elastase. The infection often begins in the external auditory canal and can spread to the temporal bone, skull base, and cranial nerves, leading to serious complications.
**Why Each Wrong Option is Incorrect**
**Option A:** Other bacteria, such as Staphylococcus aureus, can cause otitis externa, but they are not the primary cause of malignant otitis externa.
**Option B:** While diabetes mellitus is a significant risk factor for malignant otitis externa, it is not the cause of the condition.
**Option C:** Fungal infections, such as Aspergillus, can cause otitis externa, but they are not the primary cause of malignant otitis externa.
**Clinical Pearl / High-Yield Fact**
Malignant otitis externa is a medical emergency that requires prompt treatment with broad-spectrum antibiotics, including coverage for Pseudomonas aeruginosa. Early recognition and treatment are crucial to prevent serious complications and improve patient outcomes.
**Correct Answer: D. Pseudomonas aeruginosa**