Conjunctivitis drugs Flashcards
Infection of the Eye lid
blepharitis
infection of the cornea
keratitis
endophthalmitis
aqueous and vitreous humor infection
defense mechanisms of eye
Sclera and cornea act as physical barrier
tears contain sIgA and lysozyme and provide lubrication
blinking inhibits microbial attachment
Common symptoms with bacterial conjunctivitis
Bilateral eyes - usually
Discharge - mucopurulent in young children
Redness- common in older children but not infants
common symptoms with viral conjunctivitis
not usually bilateral
watery discharge
usually red
common symptoms with allergic conjunctivitis
usually bilateral
no discharge
usually red
Treatment of allergic conjunctivitis
antihistamines
but no glucocorticoids - can lead to glaucoma, cataract and 2ndary infections
most common causes of viral conjunctivitis
Neonatal = HSV
post natal = Adenovirus
Describe the adenovirus
non-enveloped, double stranded DNA virus, Lytic in epithelial cells and latent in lymphoid
spreads through fomites
most common cause of acute bacterial conjunctivitis
Children - Staph aureus, strep pneumo and haemo influ
Adults - staph aureus
Empiric treatments of conjunctivitis
Trimethoprim and polymyxin (combined in drops) called polytrim
or
Moxifloxacin (more expensive)
Mechanism of moxifloxacin
topo II and IV inhibitor
Mechanism of trimethoprim
inhibits bacterial dihydrofolate reductase.
Mechanism of polymyxin B
Binds to LPS creating holes in membrane,
Used on Gram - multi-drug resistant bacteria
Hyperacute bacterial conjunctivitis cause
neisseria
Signs of neisseria conjunctivitis
Copious yellow green discharge
gram stain reveals gram negative intracellular diplococci
grows on chocolate agar
Treatment of hyperacute bacterial conjunctivitis
System ceftriaxone promptly
What is opthalmia neonatorum
conjunctivitis occurring within the first four weeks of birth
Treatment of ophthalmia neonatorum
Prophaylaxis - erythromycin ointment
Treat - appropriate antimicrobial (usually erythromycin)
Mechanism of erythromycin and azithromycin
inhibit translation by binding 23S rRNA of 50S subunit
spectrum of macrolides
broad coverage of respiratory pathogens and chlamydia
Resistance of macrolides
Methylation of binding site and increase efflux
Adverse effects of macrolides
GI upset and hepatic failure
inhibitors of P450 enzymes
Different serotypes of Chlamydia trachomatis
inclusion conjunctivitis = serotypes D-K
Trachoma = serotypes A-C
Trachoma is the leading cause of blindness worldwide due to multiple infections b/c no long lasting immunity
Diagnosis of chlamydia trachomatis
direct fluorescent antibody
treatment of chlamydia trachomatis
systemic azithromycin and improve hygiene
treat sexual partners and prophylaxis is being used to eliminate trachoma by 2020
describe life cycle of chlamydia trachomatis
Elementary body (rigid outer membrane) enters epithelial cells -> converts to reticulate body -> replicates using binary fission
Signs and symptoms of HSV keratoconjunctivitis
similar to adenovirus but lesions can be painful especially if scarring of the cornea occurs often and only one eye
treatment of HSV keratoconjunctivitis
avoid corticosteroids
treat w/ topical trifluridine and systemic acyclovir
consider prophylactic treatment with erythromycin to prevent bacterial infection
Mechanism of trifluridine
pyrimidine analog effective against acyclovir resistant virus because it can be phosphorylated by host kinases making it more toxic and should only be used topically
signs and symptoms of keratitis
vision defects, photophobia, pain and foreign body sensation
Causes of keratitis
Viral - HSV-1 usually but adenovirus and vzv too
Bacterial - staph, pseudomonas and bacillus cereus
Fungal can be seen in warm humid climate
acanthamoeba
treatment of keratitis
bacterial - moxifloxacin eye drops
viral (HSV) - trifluridine and acyclovir
Describe pseudomonas aeroginsoa
Gram -, aerobic rod w/ flagella
can use 75 different compounds for growth
usually opportunistic infection
naturally resistant to many antibiotics and disinfectants due to its ability to form biofilms
what is pyocyanin and what does it do?
a blue pigment that inhibits mitochondrial enzymes which disrupts ciliary beating in pseudomonas keratitis
Mechanism of keratitis
Bacterial cell surface adherence factors and secreted toxins like elastase and alkaline protease destroy corneal epithelium
The host response damages the cornea leading to scarring and loss of visual acuity
Describe acanthamoeba
Single cell, eukaryote
can cause keratitis or granulomathous amebic encephalitis
treatment of acanthamoeba
Azoles
Mechanism of azoles
bind p-450 enzyme and block production of ergosterol
Can be very toxic
describe uveitis
inflammation of uveal tract that can lead to blurred vision and permanent vision loss
iritis
(also called anterior uveitis) often not infectious but has photophobia, pain and decreased visual acuity
caused by Treponema pallidum, herpes simplex and vzv
Chorioretinitis
most common type of uveitis
has floaters and no pain
blurred vision and visual field defects
Causes of chorioretinitis
usually manifestation of a systemic disease
most common causes are Toxoplamosis and CMV (looks like brushfire from periphery) esp in neonates and HIV positive individuals
Parasitic worms can also cause this (river blindness)
describe toxoplama
Most common parasitic disease, late term congenital infections are more likely to lead to blindness
diagnose with IgM serology
treat with pyrimethamine and sulfadiazine
Describe endophthalmitis
infection of vitreous and/or aqueous humors
Rare
Pain, redness and decreased vision
can be bacterial or fungal
Exogenous = recent intraocular surgery
Endogenous = spread from the blood
Treat w/ fluoroquinolone or vancomycin injected into the eye
