Malignant external otitis

 Q; 78 years old male is admitted to ICU with sepsis and visible otorrhea.  Which of the following organism is most likely to be responsible for malignant external otitis? 

 A) Pseudomonas aeruginosa 

 B) Aspergillus 

 C) Staphylococcus 

 D) Klebsiella oxytoca 

 E) Candida parapsilosis

Answer: A

Malignant external otitis is also known as necrotizing external otitis or malignant otitis externa. It is mostly seen in diabetic, elderly, or patients with immunocompromised states such as human immunodeficiency virus (HIV). Almost 95 percent of cases are due to Pseudomonas aeruginosa. It is an invasive infection of the external auditory canal and skull base. All other organisms mentioned above can be culprits but very unlikely.

Interestingly, there are few unique symptoms of this pathology. The pain is usually severe and tends to occur at night. The patient feels pain at the temporomandibular joint while chewing. If such symptoms are associated with visible otorrhea, the likelihood of malignant external otitis is high.

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References:

1. Karaman E, Yilmaz M, Ibrahimov M, Haciyev Y, Enver O. Malignant otitis externa. J Craniofac Surg. 2012 Nov;23(6):1748-51. doi: 10.1097/SCS.0b013e31825e4d9a. PMID: 23147298. 

2. Carfrae MJ, Kesser BW. Malignant otitis externa. Otolaryngol Clin North Am. 2008 Jun;41(3):537-49, viii-ix. doi: 10.1016/j.otc.2008.01.004. PMID: 18435997.