Ear infections

Question 1

Define otitis externa, otitis media, Labrinthitis and mastoiditis

Answer 1

Otitis externa = external auditory canal infection
Otitis media = middle ear infection
Labrinthitis = inner ear infection
Mastoiditis = mastoid process infection

Question 2

Signs and symptoms of acute otitis media

Answer 2

can be either viral or bacterial

usually has pain, red ear drum, pus and fever

Question 3

Define and describe otitis media with effusion

Answer 3

Its a build up of fluid in the eustachian tube.
Usually no accompanying infection in ear but associated with URI, cigarette smoke and allergies
Usually resolves on its own

Question 4

Describe pathology of acute otitis media

Answer 4

URI -> congestion of mucosa -> narrowing/obstruction of Eustachian tube prevents ventilation and drainage -> secretions build up and if a pathogen is present it causes otitis media

Question 5

Why do most children experience AOM?

Answer 5

Usually tubes are more narrow and horizontal

more common in children/males and native americans

Question 6

Common causes of AOM

Answer 6

Strep pneumoniae (25-50%)
Haemophilus influenzae nontypeable (15-30)
moraxella catarrhalis (3-20)
Viral - rhinovirus (5-22)
unidentified (16-25)

Question 7

Describe Strep pneumo

Answer 7

Gram positive diplococci

Transmitted by secretions

Question 8

Virulence factors of Strep pneumo

Answer 8

Resistance - due to changes in penicillin binding protein
Capsule - blocks phagocytosis
Choline binding proteins - bind carbohydrates present on surface of epithelial cells
neuraminidases - cleave host mucins
pneumolysin - pore forming toxin is released and disrupts cilia
Iron acquistion A (PiaA) and uptake (PiuA)

Question 9

Describe haemophilus influenzae

Answer 9

pleomorphic, gram negative, coccobacillus, non motile biofilms and facultative anaerobe
Humans are only known host
Grows on chocolate agar