Prunuske -- Conjunctivitis Flashcards
Blepharitis
eye lid infections
Conjunctivitis
conjunctiva- thin membrane infection
Kerititis
cornea infection
vision defects, photophobia, pain (cornea has lots of nerve endings), and foreign body sensation
Viral keratitis is caused by HSV-1, adenovirus, and VZV.
Bacterial keratitis Staph. aureus and epidermidis, Pseudomonas aerugrinosa, and Bacillus cereus.
Treatment- for bacteria Moxifloxacin eye drops
_ for HSV-1_ **trifluridine + acyclovir **
Keratoconjunctivitis
conjunctiva and cornea infection
Uveitis
iris, ciliary body, and choroid infection
Chorioretinitis
choroid and retinal layers infection
Blood borne route via retinal arteries, frequently manifestation of systemic disease
Congenital Toxoplasma (parasite) and CMV (ganciclovir implant) are most common especially in HIV and neonates
Endophthalmitis
aqueous and vitreous humor
tears contain what?
Secretory IgA is a dimer
Secretory piece protects IgA from being degraded
most common cause of conjunctivitis
adenovirus
(also alergies, chemical exposure)
bacterial vs. viral vs. allergic conjunctivitis
bilateral (bacterial: 50-75%; viral; 35%, A = mostly)
discharge (bacterial: macopurulent; viral: watery)
MUST ADD MORE
Allergic rhinoconjunctivitis (hay fever)
antigen –> b-cell –> IgE –> IgE binds mast cell –> subsequent exposure –> histamine release from mast cell.
Management
Antihistamines, mast cell stabilizers, nonsteroidal anti-inflammatory drugs
Avoid antigen and glucocorticoid
Steroids effective but can cause complications like glaucoma, cataract, and 2ndary infections
Viral conjunctivitis
Neonatal = ?
Post-natal = ?
HSV-1
Adenovirus
Adenovirus
non-enveloped, double-stranded DNA virus
Lytic in epithelial cells and latent in lymphoid
highly contagious spread through fomites like swimming pools
Adenovirus infects epithelial cells of respiratory tract (4,7), conjunctiva (invasive 19,37), and enteric organs (40,41,42). What determines this specificity? ... coxsackie adenovirus receptors
Acute bacterial conjunctivitis (mucopurulent)
Children- Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella
Adults- Staphylococcus aureus, Strep. Pneumonia, Escherichia coli, Pseudomonas aeruginosa, Moraxella
Empiric treatment with both Gram positive and negative coverage: Moxifloxacin solution (fluroquinolone) (best coverage, expensive, >3 yr)
What is the mechanism of action for moxifloxacin, trimethoprim, and polymyxin B?
moxifloxacin: binds DNA gyrase (TOPO II)
trimethoprim: binds to DHFR
polymyxin B: binds phosphitidal ethanolamine and creates holes in outer membrane
Hyperacute bacterial conjunctivitis
**Neisseria gonorrhoeae **
Copious yellow-green discharge (purulent)
Preauricular adenopathy
Gram stain for gram-negative intracellular diplococci and growth on chocolate agar supplemented with vancomycin, colistin, nystatin, and trimethoprim (nonsterile site)
Treat promptly with systemic ceftriaxone
Ophthalmia neonatorum
conjunctivitis or keratoconjunctivitis occurring within first four weeks of birth
(N. gonorrhoeae, C. trachomatis, Staphylococcus, Streptococcus, E. coli, H. influenzae or H. simplex)
Prophylaxis with **erythromycin ointment **
erythromycin, azithromycin
macrolides
Inhibits translation by binding 23S rRNA of the 50S subunit
Spectrum: Broad coverage of respiratory pathogens, Chlamydia
Resistance: Increased efflux, hydrolysis of drug by esterases, methylation of drug binding site
Adverse effects:
GI discomfort, Hepatic failure, and Prolonged QT interval
Inclusion conjunctivitis (serotypes D-K)
Trachoma (serotypes A-C)
_Chlamydia trachomatis _
Trachoma = leading cause of blindness worldwide
Treate with azithromycin
Chlamydia trachomatis
life cycle
Elementary body (EB) enters epithelial cells, converts to reticulate body (RB), and then replicates using binary fission
elementary body has ridgid outer body
Chronic conjunctivitis is associated with….
Blepharitis: Inflammatory disease of the eyelid margin where too much oil is produced
Stye- external localized inflammation often on lower lid due to bacterial growth in eyelash follicle, if forms inside or under eyelid called hordeolum
Chalazion- (lipogranulomas)”small lump” plugging of the meibomian gland
Treatment: Keep lid clean. Warm compress or massage to open gland. Erythromycin ointment.
keratoconjunctivitis with HSV-1
Similar presentation to adenovirus although lesions can be painful especially if scarring of the cornea occurs and often only one eye
Avoid corticosteroids since can facilitate corneal penetration
If corneal involvement treat with topical trifluridine and systemic acyclovir and consider prophylactic treatment with erythromycin to prevent bacterial superinfection
acyclovir and ganciclovir are prodrugs
Inhibits viral DNA synthesis by acting as a competitive substrate for viral DNA polymerase and lead to chain termination
requires thymidine kinase (?)
Trifluridine
pyrimidine analog effective against acyclovir resistant virus because it can be phosphorylated by host kinases also making it much more toxic and should only be used topically
