Malignant otitis externa is most commonly caused by -

Ans. is 'a' i.e., P. aeruginosa Although otitis externa is also known as swimmer's ear, malignant otitis externa isn't due to water remaining in the ear canal. Bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus often cause malignant otitis externa. The most frequent pathogen is Pseudomonas aeruginosa.