Final answer:
Malignant otitis externa is often caused by Pseudomonas aeruginosa and primarily affects elderly diabetic patients. Treatment includes specific antibiotics and antibiofilm agents when necessary. The correct multiple-choice option is (a).
Step-by-step explanation:
Malignant otitis externa, also known as necrotizing otitis externa, is a serious infection of the external ear canal, most often caused by the bacterium Pseudomonas aeruginosa. This condition primarily affects elderly diabetic patients. P. aeruginosa is known for its resistance to many antibiotics, due to mechanisms such as production of ß-lactamases, mutation of porins, and active efflux pumps.
Treatment options for infections caused by this pathogen may include ear drops containing acetic acid, antibiotics such as polymyxin B, gentamicin, and some fluoroquinolones, and steroids to reduce inflammation. Antifungals may be added if a fungal component is suspected. In cases of wound infections by P. aeruginosa, topical antibiofilm agents may be employed to disrupt biofilm formation.