A 70-year-old woman is brought to the emergency department because of a 3-day history of fever, irritability, and discharge from her right ear. She has had type 2 diabetes for many years and has been noncompliant with her medications and follow-up appointments. She appears ill. Her temperature is 39.3°C (102.7°F). On examination, moving or touching the pinna produces extreme pain. Otoscopic examination shows granulation tissue in the left ear canal with a scant amount of discharge. The tympanic membrane is clear, and there is no middle ear effusion. Initial cultures from the ear show a Gram-negative rod. Which of the following microbiological characteristics best describes the infecting organism?

Question

A 70-year-old woman is brought to the emergency department because of a 3-day history of fever, irritability, and discharge from her right ear. She has had type 2 diabetes for many years and has been noncompliant with her medications and follow-up appointments. She appears ill. Her temperature is 39.3°C (102.7°F). On examination, moving or touching the pinna produces extreme pain.  Otoscopic examination shows granulation tissue in the left ear canal with a scant amount of discharge.  The tympanic membrane is clear, and there is no middle ear effusion.  Initial cultures from the ear show a Gram-negative rod.  Which of the following microbiological characteristics best describes the infecting organism?

Quizplus · Accepted Answer

Eductional Objective: Pseudomonas aeruginosa is a nonlactose-fermenting, oxidase-positive, motile, Gram-negative rod.  It is the most common cause of malignant otitis externa (MOE), a serious infection of the ear seen in elderly diabetic patients.  MOE presents with exquisite ear pain and drainage, and granulation tissue is often seen within the ear canal.

A 70-Year-Old Woman Is Brought to the Emergency Department Because