Malignant otitis externa is due to –
**Core Concept**
Malignant otitis externa is a severe infection of the external auditory canal and surrounding structures, primarily affecting individuals with compromised immune systems, such as those with diabetes or HIV/AIDS. This condition is characterized by its aggressive progression and potential for intratemporal complications.
**Why the Correct Answer is Right**
Malignant otitis externa is typically caused by *Pseudomonas aeruginosa*, a gram-negative bacterium, which takes advantage of the compromised immune status of the patient. The infection progresses rapidly, often involving the cartilaginous and bony structures of the external auditory canal, leading to severe pain, swelling, and potentially life-threatening complications, such as intracranial extension or sepsis. The involvement of the cranial nerves, particularly the facial nerve, can lead to facial paralysis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while *Staphylococcus aureus* can cause otitis externa, it is not the primary pathogen responsible for malignant otitis externa.
**Option B:** This option is incorrect because *Candida albicans* is a fungus that can cause otitis externa in immunocompromised patients, but it is not the primary cause of malignant otitis externa.
**Option C:** This option is incorrect because *Streptococcus pneumoniae* can cause otitis media, but it is not the primary pathogen responsible for malignant otitis externa.
**Clinical Pearl / High-Yield Fact**
It is essential to consider the possibility of malignant otitis externa in patients with diabetes or immunocompromised states who present with severe external auditory canal pain and swelling, as prompt recognition and treatment are critical to preventing serious complications.
**Correct Answer: A. Pseudomonas aeruginosa**