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Neuro Block 3 > Conjunctivitis > Flashcards

Conjunctivitis Flashcards

1
Q

What is blepharitis an infection of?

A

the eye lid

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2
Q

What is keratitis an infection of?

A

the cornea

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3
Q

What uveitis an infection of?

A

the iris, ciliary body and/or choroid

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4
Q

What is chorioretinitis an infection of?

A

the choroid and retinal layers of the eye

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5
Q

What is endophthalmitis an infection of?

A

the aqueous and vitreous humor

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6
Q

What are some factors that make someone more prone to eye infections?

A

immunocompromise

anatomical abnormalitis

dysfunctional tear states

contact lens wearers

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7
Q

What defense mechanism molecules are contained in tears/

A

secretory IgA and lysozyme

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8
Q

What is the special structure of sIgA and why is this important?

A

it’s a dimer with a central secreotry piece that protects IgA from being degraded

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9
Q

What sort of immune cells are present in the conjunctiva?

A

lymphocytes, plasma cells, neutrophils, and mast cells

so you can get antibody and cytokine production

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10
Q

How is blinking an eye defense mechanism?

A

It inhibits microbial attachment

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11
Q

WHat is the discharge and eye redness from in conjunctivitis?

A

dilation and congestion of the subepithelial vessles

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12
Q

What are the three general causes of conjunctivitis?

A

bacterial

viral

allergic

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13
Q

Of the three general causes of conjunctivitis, which are more likely to be bilateral eyes?

A

allergic is almost always both

bacterial is both 50-75% of the time

viral is bilateral only 30% of the time

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14
Q

What’s tricky about eye redness in bacterial conjunctivitis in older chlidren vs .infants

A

it’s common in older children, but uncommon in infants and toddlers

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15
Q

If you have an associated acute otitis media and conjunctivitis, is it usually viral or bacterial?

A

bacterial

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16
Q

What is the general mechanism for allergic rhinoconjunctivitis (hay fever)

A
  1. exposure to an antigen
  2. B cell crease IgE antibodies to the antigen
  3. the IgE bind to mast cells
  4. Upon re-exposure to the antigen, it binds tot he IgE
  5. Cross-linking of the IgE signals degranulation of the mast cells
  6. Histamines is released into the area
  7. Histamine increases the permeability of blood capillaries and get swelling and redness in the eyes
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17
Q

What do you use in management of allergic rhinoconjunctivitis/

A

antihistamines, mast cell stabilizers, NSAIDS

also avoid the antigen in general

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18
Q

Why should steroids be avoided in allergic rhinoconjunctivitis?

A

they are effective in treating teh allergic rhinoconjuncitbitis itself, but cause complications like glaucoma, cataracts and secondary infection so it’s not worth it

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19
Q

What is the most common virus leading to conjunctivitis in neonates? In the rest of the population?

A

neonates - HSV1

rest of the population = adenovirus

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20
Q

Besides HSV1 and adenovirus, what are some other viruses that can cause viral conjunctivitis?

A

coxsackie A24, HSV 2, VZV, EBV, rubella, mumps, influenza

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21
Q

What typically precedes a viral conjunctivitis?

A

an upper respiratory infection

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22
Q

Where will you particularly see lymphadenopathy in viral conjunctivitis?

A

preauricular adenopathy

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23
Q

How do you treat viral conjunctivitis?

A

it’s usually benign and self limited

treat with cold and warm compress and maybe topical vasoconstrictors

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24
Q

What sort of virus is the adenovirus?

A

it’s a non-enveloped, dsDNA virus

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25
Where does adenovirus cause lytic infection and where does it cause latent infection?
lytic in epithelial cells and latent in lymphoid cells
26
WHy do some strains of adenoviruses infect the respiratory tract, while some do conjunctive and others do enteri corgans?
the differnt strains ahve different membrane fibers that will attach to different receptors found on different cells thoruhout the body
27
What 2 adenovirus strains very commonly cause conjunctivitis?
19 and 37
28
What new test is available to detect adenovirus hexon protein in eye swabs?
adenoplus - you dab and drag is across the lower lid
29
What is the most common bacteria causing acute bacterial conjunctivitis?
staph aureus
30
What are some other bacteria that can cause conjunctibitsi?
streptococcus pneumoniae, haemophilus influenze (kids), moraxella, e. coli, pseudomonas aeruginosa
31
If bacterial conjunctivitis is typically self limiting, why do we treat it with antibiotics?
treating decreases patient morbiditiy and transmission
32
What is the typical antibiotic used for conjunctivitis?
moxifloxacin solution - it's the vest cover for both gram positive and gram negatives in this situation
33
Since moxifloxacin solution is expensive, what oother drug combo is usually given?
trimethoprim and polymyxin B
34
Moxifloxacin is a fluoroquinolone - wha tis the mechanism of action?
it binds DNA gyrase and disrupt DNA synthesis
35
What is the mechanism of action for trimethoprim?
it's blocks DHFR so you don't have the folate pathway for making nucleotides
36
What is the mechanism of action for polymyxin B?
It will punch holes in the membranes of gram negative organisms
37
True or false, you typically do cultures of conjunctivitis to determine the species.
false - usually not necessary - treat epirically wtih broad coverage only get cultures for recurrent infections, severe infections or no response to treatment
38
What bacterial causes HYPERACUTE bacterial conjunctibitis
Neisseria gonorrhoaea (sometimes meninigtidis, but much less often)
39
What symptoms will you see with a hyperacute bacterial conjunctibitis?
copiois yellow-green discharge - purulent preauricular adenopathy (even though this is usually with the viral conjunctiitis)
40
How do you do a gram stain if you're concerned about hyperacute bacterial conjunctivitis?
you would do one because of the severity since the eyes are not sterile, you will likely pick up lots of bacteria just from normal flora, so you need to "weed" these out stain and look for intracellular diplococci grow on chocolate agar supplemented with vancomycin, colistin, nystatin and trimethroprim to kill off the normal flora and leave the neisseria if it's there
41
How do you treat hyperacute bacterial conjunctivitis? Why does it need to be quick?
systemic ceftriazone it can quickly progress to corneal ulceration and perforation
42
What is ophthalmia neonatorum?
it's conjuctibitis or keratoconjunctibitis occurring within the first month of life
43
What do we do in the US to try to circumvent ophthalmia neonatorum?
we do prophylactic erythromycin ointment in newborn eyes
44
What type of drug is erythrromycin? How does it work?
it's a macrolide it inhibits translation by binding the 23S rRNA of the 50S ribosomal subunit
45
What is the spectrum for erythromycin?
broa coverage of respiratory pathogens and chlamydia
46
Resistance to erythromycin is becoming an issue - what are the mechanisms for resistance?
increased efflux hydrolysis of drug by esterases methylation of the drug's binding site
47
What are the adverse effects of the macrolides like erythromycin?
GI discomfort hepatic failure prolonged QT interval inhibits cyt p450, so check other meds
48
What bacterial is associated with the leading cuase of blindness worldwide?
chlamydia trachomatis - because you don't get lasting immunity, recurrent infection is common, resulting in repeat damage to blindness
49
How do you diagnose chlamydia trachomatis conjunctibitis?
direct fluorescent antibody testing
50
What is the treatment for chlamydia trachomatis conjunctiitis? What other organism should you be owrried about?
azithromycin be worries about coinfection with N gonorrhoae
51
Describe the life cycle of chlamydia trachomatis.
1. elementary body enters epithelial cells 2. converts to reticular body form in the cell 3. replicates with binary fission 4. reverts back to elementary body form 5. elementary body leaves cell to infect neighbors
52
What is the isue with interferon-gamma and chlamydia trachomatis?
it can create persistent form of the infeciton which is reactivated when the antibiotic is removed
53
Which form of the chlamydia trachomatis - elementary or reticulate--will have a rigid otuer membrane?
elementary - it has to be able to survive in the environment
54
What are the two basic forms of blepharitis?
stye = localized inflammation in eyelash follicle chalazion = a lipogranuloma plug of a meibomian gland
55
What is the treatment for blepharitis?
warm compress/massage to open gland erythromycin ointment for bacterial
56
What sort of worrisome infection is herpes simplex 1 associated with?
keratoconjunctibitis
57
Although HSV1 conjunctivitis presents similar to adenovirus at first, what is the distinguishing feature/
it becomes more painful because it often causes scarring of the cornea (often only in one eye) under fluorescene you'll see a dendritic formation of the scar
58
Why should you avoid corticosteroids in treating HSV1 keratoconjunctiitis?
it's more likely to lead to corneal penetration
59
If there is corneal involvement of an HSV conjuncivitis, how should you treat it?
topical trifluridine and systemic acyclovir
60
BOth acyclovir and trifuridine are prodrugs that will act as chain terminators. Why is trifuridine more toxic and therefore only used topically?
Acyclovir is specific to viral-infected cells because it needs thymidine kinase to be phosphorylated, which is only expressedin infected cells Trifluridine is a pyrimidine analog that is phosphorylated by host kinases, so it's less specific to the viral infected cells
61
What are some symptoms besides eye redness you would have with keratitis?
vision defects photophobia pain (cornea has lots of nerve endings) foreign body sensation
62
What viruses are most commonly associated with keratitis?
HSV1 is the ost common then adenovirus and VZV
63
What bacteria are most commonly causing bacterial keratitis?
staph auerus staph epidermidis pseudomonas aeruginosa baccilus cereus
64
What ameba can cause keratitis?
acanthamoeba - often resides in improperly stores contact lens cleaning fluids
65
What is the treatment for viral keratitis? bacterial?
viral = trifluridine and acyclovir bacteria: moxifloxacin eye drops
66
Who is at the highest risk for pseudomonas aeruginosa eye infections?
contact lens wearers
67
Why is pseudomonas aeroginosa naturally resistant to many antibiotics?
it can form biofilms
68
What virulence factor can pseudomonas produce to inhibit mitochondrial enzymes and disrupt ciliary beating in keratitis?
a blue pigment called pyocyanin
69
What virulence factors will break down the corneal epithelium in pseudomonas keratitis?
elastase and alkaline protease
70
What are the two types of uveitis?
iritis - anterior uveitis chorioretinitis - posterior uveitis
71
How are the symptoms for iritis and chorioretinitis different?
iritis - photophobia, pain, decreased acuity chorioretinitis - floaters, no pain (more common)
72
Why is chorioretinitis frequency a manifestation of systemic disease?
It's affecting the retinal arteries and it's usually blood borne to that area from somewhere else in the body
73
What two congenital infections common cause chorioretinitis in neonates?
toxoplasma CMV
74
What are two worm parasitic infections that can cause eye infections - chorioretinitis in particular?
toxocara cani onchocerca volvulus (river blindness from sand flies)
75
Who typically gets endophthalmitis - it's rare.
people who have had recent intraocular surgery like cataract surgery. the agent is from normal flora like pseudomonas, staph, or candida
76
How do you treat endophthalmitis?
you inject fluoroquinoloe or vancomycin into the eye
77

Neuro Block 3 (24 decks)

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