Final answer:
The best treatment for otitis externa caused by Pseudomonas aeruginosa is Polymyxin B-neomycin-hydrocortisone (Cortisporin Otic) suspension, as it contains both an antibiotic effective against this pathogen and a steroid to reduce inflammation.
Step-by-step explanation:
A patient diagnosed with otitis externa, commonly caused by Pseudomonas aeruginosa, presents symptoms of ear pain, purulent discharge, swelling, and redness. Given the pathogen's resistance profile, the best treatment option among those provided would be the use of Polymyxin B-neomycin-hydrocortisone (Cortisporin Otic) suspension, which combines an antibiotic with a steroid to address both the infection and inflammation. This treatment aligns with the knowledge that otitis externa is effectively treated with ear drops containing antibiotics and steroids, considering that Pseudomonas spp. are resistant to many antibiotics and may require specific agents such as polymyxin B for clearance.