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Neuro Block 3 > Otitis Media > Flashcards

Otitis Media Flashcards

1
Q

What is an infection ofthe external ear called? Middle ear? Inner ear?

A

otitis externa

otitis media

labrinthitis

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2
Q

Mastoiditis is when an ear infection spreads to the mastoid, mmost commonly with which type of ear infection?

A

otitis media

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3
Q

What are the two types of otitis media?

A

acute otitis media

otitis media with effusion

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4
Q

What causes the two types of otitis media?

A

acute = bacterial or viral infection directly in the middle ear

otitis media with effusion = a buildpu of fulid in the eustachiam tube without direct infection of the middle ear (can be from URI infection, cigarette smoke, or allergies)

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5
Q

Will antibiotics help with otitis media with effusion?

A

no - there’s no infection in the ear

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6
Q

Why are both acute otitis media and otitis media with effusion equally concerning in kids?

A

they both cause hearing loss and kids need to hear to learn to speak

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7
Q

Describe the pathogenesis of acute otitis media

A
  1. URI or allergic condition causes congestion of mucosa
  2. narrowin gnad obstruction of eustachian tubes prevents ventilaiton or drainage
  3. Secretions accumulate
  4. If pathogen is present in the area it can easily proliferate and cause infection
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8
Q

Why do adenoids increase likelihood of ototis media

A

if they’re enlarged they can increase eustachian tube blockage

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9
Q

Why do young children have such high prevalence of otitis media?

A

anatomically their tubes are more narrow and horizontal than adults

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10
Q

What gender is more likely to have otitis media?

What ethnicity>

A

males

native american/alaskan natives

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11
Q

What are the 3 most common bacteria causing acute otitis media?

A

streptococcus pneumoniae (25-50%)

Haemophilus influenzae (mostly non-typable - 15-30%)

Moraxella catarrhalis (3-20%)

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12
Q

Viral otitis media is slightly less common, but what are the two main viruses that can be responsible?

A

RSV

rhinovirus

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13
Q

Remind me the shape and characteristics of streptococcus pneumoniae…what reaction is used to determine serotype?

A

gram positive diplococcus in a lancet shape

quellung reaction to determine serotypes - there are 91

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14
Q

Of the 91 serotypes, how many does the vaccine cover?

A

23 - covers hte ones most likely to cause meningitis

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15
Q

How is stremtococcus pneumoniae spread and how does it lead to otitis media?

A

transmitted by contact with secretions

usually starts with asymptomatic colonization of thr nasooropharynx

pt can be a carrier for weeks to months

if it spreads to the middle ear or terminal airways it can lead to rapid inflmammation

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16
Q

What virulence factors does strep pneumo have?

A

capsule

choline binding proeins

neuraminidases

autolysin A

penumolysin

Iron aquisition PiaA

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17
Q

What do the choline binding proteins do?

A

they bind carbohydrates present on the surface of epitheliual cells and help with attachment

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18
Q

What does neuraminidase do for strep pneumo?

A

it cleaves sialic acid in the host mucins, destroying them

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19
Q

What does the Autolysin A do for strep pneumo?

A

it degrades peptidoglycan and causes lapha hemolysis during growth

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20
Q

What does the pneumonlysin do for strep pneumo?

A

iafter the autolysin degrades the peptidoglycan of the bacteria, pneumolysin is secreted and released

it’s a toxin that disrupts host cilia

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21
Q

What molecules facilitate iron acquisiion in strep pneumo>

A

PiaA - acquisition

PiuA - uptake

22
Q

What are the characteristics of haemophilus influenzae?

A

small

pleomorphic coccobacillus

gram-negative

nonmotile

can make biofilms

facultative anaerobe

23
Q

Since haemophilus influenzae is fastidious, what do you need to grow it on?

A

chocolate agar with additional hematin X and NAD V

24
Q

How is the haemophilus influenzae that causes otitis media different from the kind thate causes meningitis?

A

the ear infection ones are nontypeable, meaning they don’t have a capusule while the ones in meningitis do have a capsule

25
Q

Why are mos thaemphilus influenzae strains resistant to penicillin?

A

express beta-lactamases

26
Q

What other mucosal sites of the body can haemophilus influenzae infect?

A

genital tract and conjuntiva of the eye

27
Q

Would the HIB vaccine cover for h. flu otitis media?

A

no, because the kinds that cause otitis media don’t hvae a capsule

however, there is a nontypeable H influenzae protein D-conjugated vaccine available now

28
Q

What are the characteristics of moraxella catarrhalis?

A

gram negative

aerobic

diplococcus

oxidase positive

nonmotile

fasticious - need to grow on chocolate agar

pili

29
Q

WHat is the main concern with moraxella catarrhalis resistance/

A

95% of M catarrhalis produces beta lactamases

30
Q

What additional test can you do on the culture to determine it it is moraxella catarrhalis?

A

the hocky puck test - the colony will slide across the agar easily

31
Q

What are the two major diagnostic approaches for diagnosin otitis media? Do you typically do cultures/

A

penumatic otoscopy first to look at TM

tympanometry to detect fluid in the middle ear

typically don’t do gram stain, but if recurrent, then you can do tympanocentesis to drain fluid and get a sample for a stain

32
Q

What antibiotics should you use to treat acute otitis media?

A

in a patient under 2 years old, start empiric treatment with amoxicillin which will cover for strep pneumoa nd haemophilu sinfluenzae

if they don’t improve in 2 days, switch to amoxicillin with clavulanate (ampicillin)

33
Q

If the patient has a penicillin allergy, what antibiotic should you prescribe for acute otitis media?

A

azithromycin

34
Q

What are some ways to reduce resistance by increases compliance?

A

reduce the number of doses per day and prescribe shorter treatment courses

35
Q

OF the moraxella catarrhalis, haemophilus influenzae and streptococcus pneumoniae, which onces would adding clavulanate be effective against?

A

Moraxella and Haemophilus - their primary resistance is thorugh beta lactamases, which clavulanate inhibitis

Streptococcus not so much - it’s main resistance is thoruhg alteration of the penicillin binding proteins, so clavulanate won’t do anything

36
Q

What do eustachian tubes do? WHat generally happens to the tube with time?

A

it’s a tube that’s placed through the TM - it will drain any fluid that’s behind the ear

the tubes tend to tall out on their own and the incision heals spontaneously

37
Q

What are the three main complications of otitis media?

A
  1. conductive hearing loss resulting in delayed speech due to performation of tympanic membrane and erosion of ossicles
  2. cholesteatoma - cyst of epithelial cells
  3. spread of infection to matoid, inner ear, temporal bone, meninges, and brain
38
Q

WHat are the symptoms of otitis externa?

A

unilateral inflammation of the ear canal

you get pain, itching, and purulent ear drainage

39
Q

What are the risk factors for otitis externa? What season is it most common in?

A

trauma to the external ear like with a Q tip

foreign bodies

excssive moisture - so after swimming

middle ear infections that can spread outward

most common in summer because of the swimming issue

40
Q

What host defense mechanism is usually protective against otitis externa?

A

the cerumen in the ear contains lysozyme and is slightly acidic, so it deters microbial growth

41
Q

What bacteria causes acute localized otitis externa

what bacteria causes acute diffuse otitis externa

A

localized = staphylococcus

diffuse = pseudomonas

42
Q

What is the huge concern with pseudomonas otitis externa?

A

it can turn to a malignant form

invasion of the adjacent bone and cartilage, leading to cranial nerve palsy and sometimes death

more ocmmon in elderly, immune compromise and poorly controlled diabetes

43
Q

What two fungi can cause otitis externa?

A

aspergillus and candida

44
Q

What are th characteristics of stphaylococcos aureus?

A

clustered, gram positive cocci

45
Q

What are the virulence factors of straphylococcus?

A

capsule

protein A

coagulase

hemolysin and leukotoxin

46
Q

What does the capsule and protein A do for staphylococcus?

A

they bind the Fc portion of IgG to interfere with phagocytosis

47
Q

What does coagulase do for staphylococcus?

A

is binds to prothrombin, initiating the polymerization of fibrin

this causes clotting and retards the migration of phacotyes to the site of ifnection

48
Q

What do hemolysin and leukotoxin do for staphylococcus?

A

they damage the host clel membrane

49
Q

How do you manage otitis externa?

A

cleansin with topic solutions that have low pH to deter growth

do NOT flush unless tympanic membrane is intact

treat with NSAIDs and acetaminophen

topical antibiotics are usually sufficient - typically neomycin + polymyxin + hydrocortisone

50
Q
A

Neuro Block 3 (24 decks)

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