Ear Infections Flashcards
What is the pathogenesis of AOM?
URI or allergy causes congestion of mucosa
Narrowing or obstruction of tubes prevents drainage
What is otitis media with effusion?
Build up of fluid in the Eustachian tube
No infection Associated with URI Cigarette smoke Allergies Resolve of it own
What can enlarged adenoids cause?
Acute otitis media
Why are ear infections more common in children!
Eustation tubes are more narrow and horizontal
What is the most common cause of AOM?
Strep pneumoniae
What are the main causes of AOM in order of most common?
Strep pneumonia Haemophilus influenza (non typable) Moraxela catarrhalis Viral (RSV, rhinovirus) Idiopathic (16-25%)
What is strep pneumonia like?
Gram positive
Diplococcus
Alcoholism, diabetes mellitus, chronic renal disease increase susceptibility
What are the strep pneumonia virulence factors?
Resistance to PBP
Capsule
Choline-binding - bind carbs on epithelium
Neuroaminidases - cleave mucins
Pneumolysin - pore forming toxin is released disrupts cilia
- iron acquisition and uptake proteins
What are some characteristics of Haemophilus influenza?
Gram neg
Coccobacillus
Biofilms
Facultative anaerobes
What bacteria has humans as the only host?
Haemophilus influenza
What blood factors are required for growth of Haemophilus influenza?
Hematin (X) and NAD (V)
Both present in chocolate agar
What type is most Haemophilus flu is most common in AOM?
Nonencapsulated nontypeable (NTHi) Colonize nasopharynx
What is the cause of resistance in NTHi?
Many express beta lactamases
Throw in a beta lactamase inhibitor
What can NTHi cause other than AOM?
Genital track
Conjunctivitis
What are some characteristics of Moraxella catarrhalis?
Gram neg Aerobic Diplococci Oxidase positive Non motile Chocolate agar Pili Adhere to upper respiratory
What percent of M. Catarrhalis produce beta-lactamases?
95%
How do you test for the presence of Moraxella catarrhalis?
Hockey puck test - easily slide across agar (not as well attached to agar)
Chocolate agar
How do you diagnosis AOM?
Pneumatic otoscope to access tympanic membrane
Tympanometry - detect fluid
If recurrent, culture, gram stain
What are some prevention strategies for AOM?
Avoid cigarette smoke
Breast feeding and avoid bottles before bed
Wash hands
Flu vaccine and 13- valent pneumococcal vaccine
What would you start 6-24 months empiric treatment for AOM?
Oral amoxicillin
Covers strep and Haemophilus
What are some side effects of a broad spec amoxicillin?
Oppertunistic infection
Allergy
If you do not improve AOM after 48 hours with amoxicillin what do you switch to?
Amoxicillin + clavulanate
What is clavulanate?
A beta lactamase inhibitor
How do you treat AOM when the Px has a penicillin allergy?
Azithromycin (macrolide)
Why would clavulanate not help a resistant strep AOM?
Because the cause of resistance is a change in the target not expression of a beta lactamase
What are some complications of otitis media?
Erosion of ossicles Cholesteatoma - cyst of epithelium cells Rupture of ear drum Infection of the mastoid Meningitis Speech delay Hearing loss
What is swimmers ear?
Otitis externa
What are some risk factors for otitis externa?
Diabetes
Moisture
Foreign bodies
Trauma
How does cerumen prevent otitis externa?
Lysozyme breaks cells
More acidic
What species causes and acute localized otitis externa?
Staph
What organism causes acute diffuse otitis externa?
Pseudomonas aeroginsoa
What organisms cause malignant otitis externa the most?
Pseudomonas aeruginosa
What two types of otitis externa does pseudomonas aeruginosa cause?
Acute diffuse
Malignant
What are some characteristics of acute diffuse otitis externa?
Itches, red, pain
What is malignant otitis externa?
Invasion of the adjacent bone and cartilage
Can progress to cranial nerve palsy and death
More In elderly, immunocompromized and diabetes
What are some common causes of fungal otitis externa?
Aspergillus
Candida albicans
How do you diagnosis otitis externa?
Hard because normal flora
KOH for fungal
Acetic acid cleansing
How do you treat otitis externa?
Neomycin(staph)
Polymixin
Hydrocortisone
NSAIDs
Topical antibiotics
What releases pneumolysin pore forming toxin?
Strep pneumonia
What causes visual field deficit most common in HIV patients?
CMV