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Neuro Med > Exam 4: ocular infections > Flashcards

Exam 4: ocular infections Flashcards

1
Q

What is blepharitis?

A

infection of the eye lid

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2
Q

What is keratitis?

A

infection of the cornea

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3
Q

What is keratoconjunctivitis?

A

infection of the conjunctiva and cornea

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4
Q

What is Uveitis?

A

infection of the middle layer of eye: iris, ciliary body, choroid

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5
Q

What is chorioretinitis?

A

infection of the choroid and retinal layers

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6
Q

What is endophthalmitis?

A

infection of the aqueous and vitreous humor

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7
Q

What are routes of infection of the eyes?

A

1) Exposed to the outside world. 2) warm moist environment conducive to microbial growth exists under the eyelids. 3) trauma related to abrasions, scratches and contact lenses can create microabrasions. 4) immunocompromised, anatomical abnormalities, or dysfunctional tear states increase susceptibility. 5) transfer from adjacent paranasal sinus or face. 6) deeper eye layers can be invaded from blood borne carriage or after surgery

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8
Q

What is the most common causitive organism of blepharitis?

A

Staphylococcus epidermidis

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9
Q

What is treatment of blepharitis?

A

Keep lid clean, warm compress or massage to open gland. ERYTHROMYCIN OINTMENT

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10
Q

What are defense mechanisms of the eye?

A

1) Sclera and cornea acts as physical barrier to prevent invasion. 2) conjuctiva: lymphocytes, plasma cells, neutrophils, and mast cells which produce antibodies and cytokines. 3) tears contain sIgA and lysozyme. 4) blinking inhibits microbial attachment

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11
Q

What is the underlying cause of conjunctivitis besides just the infection

A

dilation and congestion of subepithelial vessels

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12
Q

List characteristics of bacterial conjunctivitis

A

Bilateral only 50-74% of the time, usually MUCOPURULENT DISCHARGE IN YOUNGER CHILDREN, redness is common in older children but uncommon in infants and toddlers, Otitis media in 32-39% of cases, not pruritic

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13
Q

List characteristics of viral conjunctivitis?

A

Bilateral in 35% of cases, MILD WATERY DISCHARGE, usually red, otitis media in 10% of cases, never pruritic

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14
Q

List characteristics of allergic conjunctivitis

A

Usually bilateral and redness, rarely discharge, MAJOR PRURITIS

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15
Q

What are major noninfectious causes of conjunctivitis?

A

Hay fever, chemical reaction, prolonged use of eye meds, neoplasm, irritation from contacts or foreign body

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16
Q

What kind of immune response does the body mount to allergic rhinoconjunctivitis (hay fever)

A

IgE response (type 1 hypersensitivity)- produces IgE antibodies that prime mast cells for degranulation

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17
Q

What is the management of allergic rhinoconjunctivitis (hay fever)

A

Antihistamines, mast cell stabilizers, NSAIDs, steroids if it’s too much cause of complications

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18
Q

What is the most common cause of neonatal conjunctivitis?

A

Herpes simplex virus

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19
Q

What is the most common cause of post-natal conjunctivitis?

A

ADENOVIRUS (KNOW), Coxsackie A24, HSV1 and 2, VZV, EBV, rubella, mumps, influenza

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20
Q

What usually accompanies a viral conjunctivits?

A

upper respiratory tract infection, preauricular adenopathy

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21
Q

What is the management of viral conjunctivitis?

A

will usually resolve on it’s own, treat with cold compress and topical vasoconstrictors

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22
Q

Describe adenoviruses

A

non-enveloped double-stranded DNA virus, lytic in epithelial cells and latent in lymphoid, highly contagious and spreads through fomites and swimming pools

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23
Q

What determines the strain of adenovirus that can infect a certain cell?

A

The proteins found on its capsid and the receptor proteins found on the host cell

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24
Q

What are the most common causes of acute bacterial mucopurulent conjunctivitis in children?

A

S. aureus, Strep pneumoniae, H. influenzae, Moraxella lacunata

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25
Q

what is the most common cause of acute bacterial mucopurulent conjunctivitis in adults?

A

Staph aureus. Others include Strep pneumoniae, Strep pyogenes, Pseudomonas aeruginosa

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26
Q

What is the treatment of mucopurulent acute bacterial conjunctivitis?

A

Empiric treatment with both gram + and gram- coverage: Trimethoprim and polymyxin B ophthalmic drops (Polytrim) or the more expensive fluoroquinolones like levofloxacin and moxifloxacin

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27
Q

What is the mechanism of action of trimethoprim?

A

Broad, Bacteriostatic: inhibits bacterial dihydrofolate reductase (low affinity for mammalian enzyme)

28
Q

What is the mechanism of polymyxin B?

A

Gram negative multidrug resistance; Binds to LPS of the membrane creating holes leading to the release of cellular contents

29
Q

What is the mechanism of moxifloxacin (fluorquinolones)?

A

Gram+ and Gram-, block DNA synthesis by binding to bacterial topoisomerase II and topoisomerase IV leading to the formation of double strand breaks

30
Q

What causes hyperacute bacterial conjunctivits?

A

Neisseria gonorrhoeae (N. meningitidis can also cause it)

31
Q

What are symptoms of hyperactue bacterial conjunctivitis caused by N. gonorrheae?

A

Copies yellow-green discharge (purulent), preauricular adenopathy

32
Q

What does management of hyperacute bacterial conjuctivitis look like to determine the causative organism?

A

Gram stain for gram-negative intracellular diplococci and grow on chocolate agar supplemented with vanco, colistin, nystatin and trimethoprim

33
Q

what should you treat a patient with who has hyperacute bacterial conjunctivitis caused by N. gonorrheae?

A

SYSTEMIC ceftriaxone supplemented with topical antibiotics and irrigation

34
Q

What is ophthalmia neonatorum?

A

conjunctivitis or keratoconjunctivitis occurring within first four weeks of birth

35
Q

What are the main causes of ophthalmia neonatorum?

A

N. gonorrheae, C. trachomatis, Staphylococcus, Streptococcus, E. coli, H. simplex

36
Q

What is the prophylactic treatment of ophthalmia neonatorum?

A

Erythomycin ointment on newborn’s eyes

37
Q

What is the mechanism of the macrolides (erythromycin and azithromycin)?

A

Inhibits translation by binding to 23S rRNA of the 50S subunit

38
Q

What is the spectrum of macrolides (erythromycin and azithromycin)

A

Broad coverage of respiratory pathogens, Chlamydia

39
Q

How is resistance to macrolides (erythromycin and azithromycin) accomplished in bacteria?

A

Increased efflux, hydrolysis of drug by esterases, methylation of drug binding site

40
Q

What are adverse effects of macrolides (erythromycin and azithromycin)?

A

GI discomfort, Hepatic failure, prolonged QT interval, inhibition of cytochrome P450 enzymes

41
Q

What does Chlamydia trachomatis (serotypes D-K) cause? Serotypes A-C?

A

inclusion conjunctivitis; trachoma

42
Q

How do you diagnose Chlamydia trachomatis inclusion conjunctivitis?

A

Direct flourescent antibody, DNA probe

43
Q

What is the treatment of inclusion conjunctivits cause by Chlamydia trachomatis? Who else should also be treated?

A

systemic azithromycin and improvement of hygiene; should also treat sexual partners

44
Q

Describe infection by Chlamydia trachomatis

A

Elementary body (EB) enters epithelial cells, converts to reticulate body (RB) and then replicates using binary fission

45
Q

T/F: Chlamydia trachomatis has a rigid outer membrane in its reticulate body form? What is it?

A

false; elementary body

46
Q

What is the difference between HSV-1 and adenovirus keratocunjunctivitis?

A

Similar presentations, but HSV-1 can be painful especially if its scarring the cornea occurs and often only infects one eye

47
Q

What treatment should you avoid with HSV-1 keratoconjunctivitis? Why?

A

corticosteroids; facilitate corneal penetration

48
Q

What should you treat patients with who have HSV-1 keratoconjunctivits?

A

topical trifluridine and systemic acyclovir; consider prophylaxis with erythromycin to prevent bacterial superinfection

49
Q

What is the mechanism of trifluridine?

A

Pyrimidine analog; can be phosphorylated by host kinases to prevent DNA replication (very toxic)

50
Q

What are symptoms of keratitis?

A

vision defects, photophobia, pain (cornea has lots of nerve endings) and foreign body sensation

51
Q

What causes susceptibility to developing keratitis?

A

trauma, dying of epithelia, hypoxia increases susceptibility

52
Q

What are the viral causes of keratitis?

A

HSV-1 mostly; adenovirus and VZV

53
Q

What are the causes of bacterial keratitis?

A

Staph aureus and epidermidis, Pseudomonas aeruginosa

54
Q

What amoeba can cause keratitis?

A

Acanthamoeba

55
Q

What is the treatment for bacterial keratitis? Viral keratitis?

A

Moxifloxacin eye drops; trifluridine and acyclovir

56
Q

What are characteristics of Pseudomanas aeruginosa?

A

Gram-, aerobic rod, flagella

57
Q

Who is at greater risk for P. aeruginosa eye infection?

A

Contact lens wearers, trauma to eye

58
Q

What are the virulence factors that help P. aeruginosa establish infection?

A

Secretes elastase and alkaline protase to destroy corneal epithelium

59
Q

What is the treatment for acanthamoeba?

A

Ketoconazole

60
Q

What are the characteristics of acanthamoeba?

A

Single cell, eukaryote, keratitis or granulomathous amebic encephalitis

61
Q

What are most common causes of Uveitis?

A

Treponema pallidum, HSV, VZV

62
Q

What are the most common causes of Chorioretinas?

A

T. gondii and CMV, especially in HIV+ patients and neonates; Also Toxocara canis and Onchocerca volvulus

63
Q

What is the treatment of toxoplasma gondii?

A

sulfadiazine and pyrimethamine

64
Q

How do you diagnose T. gondii?

A

IgM serology

65
Q

What are most common causes of endophthalmitis?

A

Usually after intraocular surgery; Pseudomonas, Staphlyococcus, Condida

66
Q

What is the treatment of endophthalmitis?

A

Fluoroquinolones or vanco injection into eye

Neuro Med (39 decks)

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