A 70-year-old patient with long-standing type 2 diabetes mellitus presents with complaints of pain in the left ear with purulent drainage.

A 70-year-old patient with long-standing type 2 diabetes mellitus presents with complaints of pain in the left ear with purulent drainage. On physical exam, the patient is afebrile. The pinna of the left ear is tender, and the external auditory canal is swollen and edematous. The peripheral white blood cell count is normal. The organism most likely to grow from the purulent drainage is
a. Pseudomonas aeruginosa
b. Staphylococcus aureus
c. Candida albicans
d. Haemophilus influenzae
e. Moraxella catarrhalis

Answer:
a. Pseudomonas aeruginosa

Discussion: Ear pain and drainage in an elderly diabetic patient must raise concern about malignant external otitis. The swelling and inflammation of the external auditory meatus strongly suggest this diagnosis.
This infection usually occurs in older diabetics and is almost always caused by P. aeruginosa.
H. influenzae and M. catarrhalis frequently cause otitis media, but not external otitis.