Infectious Diseases of the External Eye Flashcards
what are the names of the anitgen-presenting cells of the ocular surface?
Langerhans cells
which bacteria can invade the cornea through an intact epithelium?
“N and N Can Lyse wHole Skin”
Neisseria gonorrhea, Neisseria meningitidis, Corynebacterium diphtheriae, Listeria monocytogenes, Haemophilus influenzae biotype III, Shigella species
Match the infectious agent with its associated virulence factor:
- Pseudomonas
- HSV
- Candida albicans
- Adenovirus
- Acanthamoeba
a. cell surface proteins that mimic integrins
b. collagenase
c. elastase and alkaline protease
d. surface protein that attaches to heparan sulfate
e. surface protein that attaches to sialic acid
- c
- d
- a
- e
- b
Collection method for material for cytology?
dacron swab or spatula, glass slide, fixed in methanol or acetone for immunofluorescent staining
Which microbes are the following stains or culture media used for?
- Blood and chocolate agar
- Lowenstein-Jensen agar
- Sabouraud’s agar
- Nonnutrient agar with E. coli overlay
- Gram stain
- Calcofluor white
- Ziehl-Neelsen stain
- Giemsa
- Aerobic and anaerobic bacteria
- Mycobacteria
- Fungi
- Acantamoeba
- bacteria and fungi
- Acanthamoeba
- Mycobacteria (same thing as acid-fast stain!)
- Acanthamoeba, other parasites (malaria)
True or False: conjunctival swabbing should be performed without topical anesthesia
True (minimizes contamination and inhibitory effects)
Match the following viruses with the appropriate description (one answer is used twice):
- herpesviruses
- adenoviruses
- poxviruses (molluscum, smallpox)
- papovaviruses (HPV)
- picornaviruses (enteroviruses)
- togaviruses (rubella, yellow fever, dengue)
- orthomyxoviruses (influenza)
a. negative-sense single-stranded RNA virus with icosahedral capsid and no envelope
b. positive-sense single-stranded RNA virus with no envelope
c. double-stranded DNA virus with icosahedral capsid and envelope studded with viral glycoproteins
d. double-stranded DNA virus with enveloped complex capsid and a distinctive brick or ovoid shape
e. negative-sense single-stranded RNA virus with an enveloped icosahedral capsid
f. double-stranded DNA virus with non-enveloped icosahedral capsid
- c
- f
- d
- f
- a
- b
- e
patient with bilateral recurrent ocular HSV?
immunocompromised state (HIV, atopic dermatitis, etc.)
appearance of HSV dendrite after fluorescein and rose bengal staining?
bed of ulcer stains green from fluorescein due to lack of cell-cell tight junctions; cytopathic swollen corneal epithelium stains red/violet from rose bengal. Overall appearance is thinner red/violet staining outlining edges of defect with a broader diffuse green staining bordering both sides of the red/violet staining
Oral antiviral doses (acute and prophylactic) for recurrent ocular HSV? Acute ocular VZV? Special considerations in AIDs patients?
HSV: 500mg acyclovir 5x/day, 500mg valacyclovir TID or 1000mg BID; acute treatments for 10 days. Prophylaxis with 400 mg acyclovir BID.
VZV: 800mg acyclovir 5x/day, 1000mg valacyclovir TID. Treat for 7-10 days
AVOID valacyclovir in AIDS patients due to risk of TTP-HUS in immunocompromised patients. Also, severely immunocompromised patients with HZO require IV acyclovir to mitigate risk of disseminated zoster.
most common cause of infectious corneal blindness in the US?
HSV stromal keratitis
differential for stromal keratitis?
HSV, VZV, EBV, mumps, syphilis, lyme, sarcoid, acanthamoeba, Cogan syndrome
corneal stromal and epithelial edema in a round or oval distribution and underlying KP?
disciform keratitis from either HSV or VZV
describe the key findings of the HEDS study
- topical steroids decrease stromal inflammation in HSV keratitis when given concomitant prophylactic antivirals
- no specific triggers/stresses were implicated as causes for HSV recurrence
- prophylactic antivirals decrease HSV recurrence
- acyclovir did not provide additional benefit in HSV epithelial or stromal keratitis in patients already receiving topical trifluridine (and topical steroids as well in the case of stromal keratitis).
- statistically insignificant trend suggesting acyclovir may be beneficial in HSV iritis in addition to steroids, but too few patients were studied
Compare HSV and VZV by the following:
- dermatomal distribution
- pain
- dendrite morphology
- skin scarring
- post-herpetic neuralgia
- iris atrophy
- bilaterality
- recurrent epithelial keratitis
- corneal hypoesthesia
HSV / VZV
- incomplete / complete
- moderate / severe
- central ulcer with terminal bulbs / smaller pseudodendrite without central ulcer
- no / common
- no / common
- patchy / sectoral
- uncommon / no
- common / rare
- sectoral or diffuse / may be severe
what type of vaccine is the varicella zoster vaccine?
live attenuated
cause of nummular corneal infiltrates?
VZV
treatment of post-herpetic neuralgia?
capsaicin cream, gabapentin, pregabalin (Lyrica), amitriptyline
latency site of Epstein-Barr virus? Cytomegalovirus?
B lymphocytes
CD34+ myeloid progenitor cells
sectoral necrotizing retinitis in AIDS patient?
CMV retinitis
treatment of CMV keratitis?
ganciclovir or valganciclovir
IOP in CMV uveitis?
elevated
Subtype(s) of adenovirus that cause(s) the following:
- simple follicular conjunctivitis
- pharyngoconjunctical fever
- EKC
- multiple serotypes
- serotype 3 or 7
- serotypes, 8, 19, or 37 subgroup D
ocular findings suggestive of EKC?
severe follicular conjunctivitis, petechial conjunctival hemorrhages, membrane or pseudomembrane, SEIs
indications for topical steroids in EKC?
Bilateral vision-impairing SEIs or membrane formation. Must use steroids with caution because they can prolong viral shedding and induce dependence. Also, they do not alter the natural course of the disease
general course of corneal pathology in EKC?
fine PEE -> course PEE -> SEIs -> SEIs + fine PEE
differentiate molluscum lesion v keratoacanthoma
both are nodular with central umbilication, but molluscum lesions are smaller and with less inflammation
type of conjunctival reaction associated with molloscum?
chronic follicular conjunctivitis
intracytoplasmic inclusion bodies in molluscum?
Henderson-Patterson corpuscles
extensive facial and eyelid molluscum?
AIDS
treatment for molluscum?
wait for spontaneous resolution (although can take months to years), excision, cryotherapy, or incision of central portion
findings in and treatment of ocular vaccinia (smallpox virus)
- severe periorbital pustules, conjunctivitis, keratitis
- topical trifluridine; vaccinia-immune globulin for severe disease
HPV subtypes associated with benign skin or conjunctival papilloma? with squamous cell cancer?
- subtypes 6 and 11 are benign
- subtypes 16 and 18 have risk of malignant transformation
classic measles triad?
cough, coryza, and follicular conjunctivitis
corneal ulceration in malnourished child from underdeveloped country?
measles keratitis in vitamin-A deficient child
rare but fatal complications of measles?
subacute sclerosing panencephalitis
causes of acute hemorrhagic conjunctivitis?
enterovirus type 70, coxsackievirus A24, adenovirus type 11
host cells for HIV?
CD4+ T cells, monocytes/macrophages, dendritic cells
rare but serious complication of enterovirus type 70?
polio-like paralysis (with permanent neurologic deficits in 1/3 of affected individuals)
Classify the following bacteria as Gram-positive v Gram-negative and cocci v rods v filaments:
- Actinomyces
- Bacillus
- Bartonella
- Corynebacterium
- Enterobacter
- Enterococcus
- Haemophilus
- Mycobacterium
- Neisseria
- Nocardia
- Propionibacterium
- Pseudomonas
- Staphylococcus
- Streptococcus
- GP filament
- GPR
- GNR
- GPR
- GNR
- GPC
- GNR
- GP filament
- GNC
- GP filament
- GPR
- GNR
- GPC
- GPC
Which bacteria’s virulence factors include streptolysin, C5a peptidase, M protein, pyrogenic exotoxin, and hyaluronidase? Briefly describe the function of each virulence factor.
- beta-hemolytic Streptococci (ex Strep pyogenes)
- streptolysin: lyses erythrocytes, platelets, and neutrophils
- C5a peptidase: cleaves C5a, an important neutrophil chemoattractant
- M protein: resist phagocytosis by neutrpophils
- pyrogenic exotoxin: causes fever (Scarlet fever) or shock
- hyaluronidase: facilitates tissue invasion (think Vitrase)
Which bacteria appear as lancet-shaped diplococcic?
Streptococcus pneumoniae
bacteria present in Bitot-spots?
Corynebacterium xerosis
common cause of post-traumatic endophthalmitis?
Bacillus cereus
enzyme utilized by Pseudomonas aerugniosa to break down corneal stroma?
elastase and alkaline protease
major virulence factor of Haemophilus influenza type B?
capsule (splenectomized patients must have the Hib vaccine due to the spleen’s role in defense against encapsulated bacteria)
stain used to visualize Bartonella henselae? natural reservoir of this bacteria?
Warthin-Starry staining; cats
culture medium used for Mycobacteria?
Lowenstein-Jensen
two forms of chlamydia and relevance of each
elementary body: infectious form, can live outside host
reticulate body: obligate form, replicated intracellularly
methods to detect spirochetes?
dark-field illumination, silver staining, or immunocytology
unique structural feature of spirochetes?
endoflagella
natural reservoir of Borelia burgdorferi?
white-footed mouse (transmitting vector = deer tick)
distinguish between the two groups of fungi?
yeasts: round or oval fungi that reproduce by budding; may have pseudohyphae
molds: multicellular fungi composed of tubular hyphae, either septate or non-septate, that grow by branching and apical extension
fungal stain? which fungi are Gram-positive?
Gomori methenamine silver. only Candida
Classify the following fungi as yeasts, septate molds, or nonseptate molds:
- Absidia
- Aspergillus
- Candida
- Cryptococcus neoformans
- Curvularia
- Fusarium
- Mucor
- Rhinosporidium
- Rhizopus
- nonseptate mold
- septate mold
- yeast
- yeast
- septate mold
- septate mold
- nonseptate mold
- yeast
- nonseptate mold
American climate where yeasts comprise a disproportionate percentage of fungal keratitis?
cooler northern climes
risk factors for oculomycosis?
trauma with vegetative matter, topical steroids, contact lens use
protozoa with hardy double-walled cyst?
acanthamoeba
vector for leishmaniasis? ocular pathology?
female sandfly; granulomatous eyelid ulcer
Sub-Saharan African patient with skin nodules and snowflake peripheral corneal opacities? Mode of transmission? Co-infecting organism? Treatment?
Onchocerciasis (river blindness). Blackfly. Wolbachia (endosymbiotic bacteria necessary for onchocercial filariae reproduction). Ivermectin for filariae, doxycycline for Wolbachia
common causes of visceral larval migrans?
Toxocara canis and Toxocara cati
intestinal tapeworm that can release eggs which can migrate to orbit or eye and form hydatid cysts? method of transmission?
Taenia solium (pork tapeworm), from ingestion of undercooked pork, causing cysticercosis
normal eyelid inhabitant that has been associated with rosacea and blepharoconjunctivitis? characteristic clinical finding? treatment
Demodex; waxy sleeves around eyelash follicles; dilute tea tree oil
treatment of pediculosis?
mechanical removal of lice and nits with jewelers and suffocation of remaining lice with the use of any ointment BID x 10 days. Bed sheets, clothing, toys, etc. should be washed and dried at the highest possible temperature
causes of hyperacute bacterial conjunctivitis?
Neisseria gonorrhea (or, less likely, N meningitidis)
unilateral bacterial conjunctivitis?
check nasolacrimal system for obstruction, dacrocystitis, canaliculitis
most common causes of acute purulent bacterial conjunctivitis?
Strep pneumo, H influenza, S aureus, Strep viridans
bacterial conjunctivitis associated with conjunctival membranes and preauricular adenopathy?
gonococcal
culture media for N gonorrhea?
chocolate agar or Thayer-Martin media
treatment of gonococcal conjunctivitis?
- IM ceftriaxone for all age groups. Topical therapy is adjunctive, but erythromycin ointment should be added if there is corneal involvement in neonates
- If PCN allergy: spectinomycin or fluoroquinolone
- Treat sexual partners
- Co-treat for chlamydia with oral azithromycin or erythromycin
Name 5 ways that neonatal chlamydial conjunctivitis differs from that in adults.
- no follicular response
- more mucopurulent discharge
- responds more readily to topical medications
- pseudomembranes can develop on the tarsal conjunctiva
- intracyctoplasmic inclusions are seen more readily with Giemsa stain
Diagnosis of chlamydia conjunctivitis?
Gram and Giemsa stain of conjunctival scrapings
Treatment of neonatal chlamydial conjunctivitis?
systemic erythromycin (due to risk of systemic infections like pneumonitis and otitis media)
Serotypes of C trachomatis that cause the following:
- trachoma
- adult and neonatal inclusion conjunctivitis
- lymphogranuloma venereum
- A-C
- D-K
- L1, L2, L3
leading cause of preventable blindness worldwide?
trachoma
severe follicular reaction on superior tarsal conj?
trachoma
Linear or stellate scarring of superior tarsus in patient with chronic follicular conjunctivitis: name and cause
Arlt line, trachoma
Limbal depressions seen in trachoma: name and what do they represent?
Herbert pits; involuted and necrotic follicles
How is clinical diagnosis of trachoma made?
At least 2 of the following:
- superior tarsal conj follicles
- characteristic tarsal conj scarring (such as Arlt line)
- limbal follicles or Herbert pits
- vascular pannus most marked on the superior limbus
Treatment of trachoma?
1g oral azithromycin once, or tetracycline ointment BID x 2 months, or oral erythromycin for resistant cases
follicular conjunctivitis + cervicitis + urethritis
chlamydial inclusion conjunctivitis
Findings in Parinaud oculoglandular syndrome? Most common cause?
unilateral granulomatous conjunctivitis and regional lymphadenopathy; Bartonella henselae
Role for tarsorrhaphy and bandage contact lenses for corneal epithelial defects in patients with a history of contact lens wear?
NONE! It is contraindicated
most common bacterial pathogen in contact-lens related keratitis?
Pseudomonas aeruginosa
nonsuppurative bacterial keratitis with intact epithelium: name and most common cause?
infectious crystalline keratopathy, alpha-hemolytic streptococcus (S viridans)
classic cause of post-LASIK infectious keratitis?
atypical mycobacteria
Contrast bacterial and fungal keratitis with regards to the following:
- conjunctival injection
- pain
- appearance of infiltrate
Fungal has
- less injection
- pain out of proportion
- irregular, feathery margins
treatment of filamentous keratitis?
topical natamycin, except amphotericin B for aspergillus
treatment for yeast keratitis?
amphotericin B
virulence factors of acanthamoeba
mannose-binding protein, collagenase, double-walled cyst
ring corneal infiltrate with pain out of proportion to exam
acanthamoeba
pathognomonic finding for acanthamoeba keratitis?
radial perineuritis
diagnosis of acanthamoeba
culture on non nutrient agar with E coli overlay; stain with acridine orange, calcofluor white, Giemsa, or PAS; direct visualization of cysts with confocal microscopy
treatment of acanthamoeba keratitis
biguanides (PHMB)
ocular manifestations, vector, and treatment for loiasis?
conjunctivitis; female deer fly; extraction of worm + diethylcarbamazine or ivermectin
