Which condition is a known risk factor for malignant otitis externa?

• A. Diabetes mellitus
• B. Hypertension
• C. Asthma
• D. Hyperlipidemia

Answer: (A)

Malignant otitis externa is a severe infection of the external auditory canal that can spread to surrounding tissues, including the skull base. The most important factor that predisposes someone to this invasive infection is diabetes mellitus, especially with poor glycemic control. Diabetes impairs immune function and reduces blood flow to tissues, making it harder for the body to fight off bacteria—most commonly Pseudomonas aeruginosa—that take hold in the ear and can travel deeper. This combination of immune compromise and reduced tissue defense helps explain why malignant otitis externa occurs preferentially in diabetics, particularly older adults. Other listed conditions do not inherently create the same increased vulnerability to this deep, invasive ear infection.