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IBI Test 4 > B3.054 Ear Infections > Flashcards

B3.054 Ear Infections Flashcards

1
Q

how does primary otalgia present in an ear exam?

A

abnormal

discharge, tinnitus, hearing loss, vertigo

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2
Q

what structures of the ear have no pain fibers?

A

inner ear structures (cochlea, semicircular canals) cranial enervation

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3
Q

how does secondary otalgia present in an ear exam?

A

normal

referred pain due to sensation fibers from cranial and cervical nerves

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4
Q

common causes of primary otalgia

A

otitis media
otitis externa
foreign bodies
barotrauma (diving, air travel)

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5
Q

common causes of secondary otalgia

A 
dental caries, periodontal abcesses
pharyngitis, tonsillitis
TMJ syndrome
cervical spine arthritis
idiopathic
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6
Q

less common causes of primary otalgia

A

malignant (necrotizing) otitis externa
Ramsay Hunt syndrome
viral myringitis
cellulitis/chondritis/pericondritis, polychondritis, trauma, mastoiditis

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7
Q

signs of otitis media

A

recent URTI

red/cloudy and immobile tympanic membrane

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8
Q

signs of otitis externa

A

swimmers ear
ear phone use
white discharge

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9
Q

signs of malignant (necrotizing) otitis externa

A

diabetes, elderly immunocompromised

painful, granulation tissue

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10
Q

signs of Ramsay Hunt syndrome

A

vesicular rash

vertigo, hearing loss, tinnitus

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11
Q

what is Ramsay Hunt syndrome

A

reactivated VZV spreading to facial nerves

paralysis and rash affecting ear and mouth

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12
Q

4 primary acute otitis media pathogens

A

S. pneumo
H. influenzae
M. catarrhalis
S. pyogenes

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13
Q

3 primary acute otitis externa pathogens

A

s. epidermidis
p. aeruginosa
s. aureus

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14
Q

classify the Haemophilus species

A

small, gram - rods/coccobacilli
non-motile, non-sporulating
aerobic or facultative anaerobes
colonize mucosal surfaces of humans and animals

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15
Q

Haemophilus nutrition requirements

A 
complex
X factor (hematin)
V factor (NAD)
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16
Q

discuss the strains of H.influenzae

A

most commonly associated w human disease
6 capsular antigenic serotypes (a-f)
non-encapsulated (nontypeable) strains rarely cause invasive disease

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17
Q

most virulent strain of H. influenzae

A 
Type b (Hib)
>95% of invasive infections
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18
Q

how does Hib colonize the oropharynx?

A 
fimbrae (adhesins)
IgA protease (breaks down mucosal IgA)
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19
Q

what is the function of Hib LPS

A

impairment of ciliary function

damage to respiratory epithelium

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20
Q

how does Hib invade bloodstream?

A 
polyribitol capsule (PRP)
anti-PRP antibodies are protective
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21
Q

what other sites can Hib invade? how?

A 
hematogenous spread:
joints
meninges
CNS
all using PRP
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22
Q

what is the Hib virulence factor for disseminated disease?

A

LPS (endotoxin)

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23
Q

discuss the Hib epidemiology

A

humans only host
transmission via resp droplets
mainly pediatric disease

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24
Q

what is the Hib 2nd gen conjugate vaccine made up of?

A

purified PRP conjugated to carrier proteins

combo vaccines: DTaP-Hib and Hep B-Hib

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25
Q

what type of cells mediate the immune response to the vaccine?

A

T cell dependent antigens
protective antibody response in infants >2 months of age
prior protection through maternal antibodies

26
Q

who can get the Hib vaccine?

A

infants >6 weeks

not >5 years unless immunocompromised

27
Q

how to identify Hib through lab tests

A 
gram stain of CSF or synovial fluid
antigen (PRP) detection in CSF or urine
culture 
-requires media containing factors V and X
-chocolate agar
-SBA w/ s. aureus (hemolytic)
28
Q

what is NTHi?

A

nontypable H.influenzae

29
Q

where is NTHi located?

A

colonize nasopharynx of most individuals during the first few months of life, remain throughout life
localized spread can lead to disease

30
Q

common illnesses caused by NTHi

A

otitis media
sinusitis
pneumonia

31
Q

treatment oh H. influenzae

A

penicillin resistance common in US (30%)
for invasive: 3rd gen ceph
for otitis media/sinusitis: ampicillin, ceph, fluoroquinolone

32
Q

characterize pseudomonas

A 
gram -, motive bacilli
obligate aerobes
ubiquitous in environment
opportunistic pathogen
common nosocomial
33
Q

discuss the overarching properties of p. aeruginosa

A

most common human pathogenic pseudomonad
opportunistic
common nosocomial

34
Q

what types of infections does p. aeruginosa primarily cause?

A

skin
pulm
outer ear
eye

35
Q

what are the virulent properties of the P.aeruginosa capsule

A

antiphagocytic
contributes to antibiotic resistance
adhesin
polymer of mannuronic and glucuronic acid

36
Q

what is another name for the p.aeruginosa capsule

A

alginate

37
Q

discuss the regulation of capsule production in p.aeruginosa

A

environmental (osmoregularity, nitrogen) and quorum sensing
produced at high levels in lungs (particularly in CF of immunocompromised patients)
production ceases in vitro
BASICALLY, can sense conditions, when conditions are appropriate, capsules grow

38
Q

what is the difference between in vitro p.aeruginosa and p.aeruginosa cultures from CF lung?

A

in vitro: no capsule, smooth and pigmented
flagella+, pili+, alginate-
CF lung: mucoid colonies of highly encapsulated bacilli, shiny
flagella-,pili-,alginate+

39
Q

what appearance can a capsule give on biofilm?

A

halo

40
Q

p.aeruginosa exotoxin A

A

A-B toxin: A subunit ADP ribosylates elongation factor EF-2

affects protein synthesis

41
Q

p.aeruginosa Exotoxin S

A

major virulence factor
injected T3SS effector protein
disrupts signal transduction and blocks phagocytosis

42
Q

p.aeruginosa exotoxin U

A

cytotoxic for macrophages

43
Q

p.aeruginosa elastase

A 
degrades elastin (protein in pulmonary and endothelial tissues)
production regulated by quorum sensing
44
Q

what types of infections does p.aeruginosa cause in healthy people?

A 
folliculitis "hot tub rash"
otitis externa "swimmers ear"
eye infections (trauma)
45
Q

describe acute otitis externa

A

edema and desquamating epithelium, soft cerumen, purulent discharge (has to be removed prior to treatment of the infection)

46
Q

default treatment of otitis externa

A

eardrops
-mild: acetic acid + propylene glycol + hydrocortisone
-moderate to severe: ciprofloxacin + hydrocortisone
no neomycin drops if TM is ruptured

47
Q

otisis externa prevention

A

alcohol eardrops

48
Q

what types of infections does p.aeruginosa in immunocompromised people?

A

bacteremia
burn wound infections
malignant otitis externa
pulmonary infections

49
Q

when do burn wounds become infected with p.aeruginosa?

A

> 2 weeks

50
Q

pathogenesis of malignant otitis externa

A

spreads from ear to nearby tissues, bone, cranial nerves, brain
95% p.aeruginosa
DOC: IV ciprofloxacin
early diabetics, AIDS, chemo

51
Q

conditions that are susceptible to pulmonary infections caused by p.aeruginosa

A

COPD
CF
neutropenia

52
Q

discuss the presence of p.aeruginosa in CF patients

A

80-90% of patients are colonized
lungs colonize by age 3
biofilm formation

53
Q

what does p.aeruginosa cause in CF patients

A

recurrent episodes of pneumonia with increasing frequency

antibiotics select for highly resistant strains

54
Q

pathogenesis of pneumonia due to p.aeruginosa

A

aspiration of upper respiratory tract secretions

can lead to bacteremia, shock, alveolar hemorrhage, and lung necrosis

55
Q

risk factors for p.aeruginosa pneumonia

A 
neutropenia
chronic lung disease
CHF
mechanical ventilation
lung burns
most common in ICU and nursing homes
56
Q

identification of p.aeruginosa on culture

A 
obligate anaerobe
catalase +
oxidase +
green pigmented, often fluorescent (mix of blue pyocyanin and yellow fluorescin)
siderophores
fruity smell
57
Q

what is pyocyanin

A

toxin found in patients’ airway secretions

affects multiple cellular functions

58
Q

what are the effects of pyocanin

A 
intracellular oxidative stress
low ATP (cilia, CFTR)
low NADPH (antibacterial)
gene expression
-down: catalase
-up: oxidative stress response, mucins, cytokines, chemokines
innate immune mechanisms: neutrophils
59
Q

treatment of systemic p.aeruginosa

A

multidrug resistance common
initial empiric combination treatment with antipseudomonal B-lactam + B-lactamase inhibitor + aminoglycosides
monotherapy chosen on basis of local susceptibility patterns

60
Q

last resort treatment of p.aeruginosa

A

polymyxin E

solubilizes bacterial membranes

IBI Test 4 (21 decks)

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