In the latest Case Record of the Massachusetts General Hospital, a 20-year-old man was transferred to the hospital because of recurrent ear pain for 8 months despite antibiotics, with new fever and headache. Imaging showed opacification of the middle ears and mastoid air cells and erosion of the right temporal bone.
Intracranial bacterial infections can be caused by bacteremia (particularly in patients with right-to-left shunting, such as with a patent foramen ovale or large pulmonary arteriovenous malformations), direct inoculation (through traumatic or surgical wounds), and spread from infected sinuses, mastoid air cells, or the middle ears.
• Which organisms are commonly associated with chronic otitis media?
Aerobes associated with chronic otitis media include proteus species and Pseudomonas aeruginosa; Staphylococcus aureus, including methicillin-resistant S. aureus, is also common. The most common anaerobes are bacteroides, peptococcus or peptostreptococcus, and Propionibacterium acnes. Because of the variety of organisms that could be involved, broad-spectrum antibiotics should be administered. In contrast, the most common pathogens associated with acute otitis media are S. pneumoniae, H. influenza, and Moraxella catarrhalis.
• What are potential complications of chronic otitis media?
Chronic otitis media can cause intracranial and extracranial complications by one of the following four mechanisms: direct erosion through bone, which typically leads to extradural abscess, subperiosteal abscess, meningitis, or venous sinus thrombosis; thrombophlebitis, which typically leads to brain abscess; extension through normal anatomical paths (e.g., cochlear oval and round windows), which typically leads to sensorineural hearing loss and vertigo; and extension through traumatic or iatrogenic bony defects.
Morning Report Questions
Q: What is a cholesteatoma?
A: A cholesteatoma is a cystlike mass of squamous epithelial debris in the middle ear. An acquired cholesteatoma typically develops from a retraction of the tympanic membrane due to chronic infection. Such retraction typically occurs in the posterosuperior quadrant or the pars flaccida of the tympanic membrane and may be associated with a perforation of the tympanic membrane or purulence. Abundant desquamated keratin is diagnostic of a cholesteatoma, which is not a true neoplasm and has nothing to do with cholesterol but, rather, is a keratoma (a pseudotumor of keratin) resulting from displacement of the squamous-lined tympanic membrane.
Q: Why would strongyloides be a consideration in a patient with gram-negative bacteremia and meningitis?
A: Patients with strongyloides are usually immunocompromised, and the filariform larvae moving out of the gastrointestinal tract carry gram-negative organisms that seed the blood and in some instances the meninges. During this initial process, eosinophilia is not necessarily observed, because of the overwhelming leukocytosis.