Conjunctivitis Flashcards
What are the order of layers in the back of the eyeball?
Sclera –> Choroid –> Retina –>
What is in the center of the macula?
Fovea
Where is the conjunctiva?
Covering the Sclera
What sinuses are near the eye that infection could spread from?
Frontal Sinus, Ethmoid sinus, Maxillary Sinus
How do pathogens get into deeper eye layers?
From blood borne carriage
What is blepharitis? What is it associated with?
Inflammatory disease of eyelid margin where too much oil is produced - chronic conjunctivitis
What organism is most often associated with chronic conjunctivitis and blepharitis? What do you treat with?
Staphlyococcus epidermis [Hard to erradicate] - Often we may not want to treat this with antibiotics since they are so recurring - like onchocerciasis
What is a stye/hordeolum?
It’s localized inflammation often on lower lid due to bacterial growth in eyelash.
How to treat a blepharitis/stye?
Keep the eyelid clean. Use warm compress or massage to open gland. Use Erythromycin ointment.
What is the mechanism of Erythromycin/Azithromycin?
Inhibits translation by binding 23S rRNA of the 50s subunit in bacteria.
What is the spectrum of Erythromycin/Azithromycin?
Broad coverage of rep. pathogen, Chlamydia
What resistance developed against Erythromycin/Azithromycin?
Increased efflux, hydrolysis of drug by esterase’s, methylation of drug binding site
What are adverse effects of erythromycin/azithromycin?
GI discomfort, hepatic failure, and prolonged QT interval
–> inhibitors of cytochrome p450 enzymes (check with other medications)
What class and mechanism if Moxifloxacin?
Fluoroquinolone
Bactericidal, inhibits DNA replication (binary fissue) by binding bacterial DNA topo II (gyrase) and IV
What is the spectrum of moxifloxacin?
Broad spectrum, Gram + or - & atypical like Mycoplasma
Hospital acquired pneumonia & UTIs
What is the resistance of moxifloxacin?
Overprescribed for UTI, respiratory and acute GI infections
Active efflux of drug
Mutations in topoisomerases
What are the adverse effects of moxifloxacin?
GI side effects, confusion, photosensitive
-Not good for pregnant & breastfeeding women due to arthropathy
What are important facts to remember with moxifloxacin?
It creates chelate cations so don’t take with calcium, iron, aluminum and zinc - avoid dairy and juice with Ca
-Adjust for renal dysfunction
What is the mechanism for Polymyxin B?
Binds to LPS (lipopolysaccharide) in the membrane creating holes ultimately leading to the release of cellular contents
What is the spectrum for Polymyxin B?
Multi drug resistant Gram – bacilli including Pseudomonas aeruginose and Klebsiella pneumoniae
-Used in combo with other antibiotics to help facilitate entry
What are side effects of Polymyxin B?
Nephrotoxicity
How does resistance develop against Polymyxin B?
- It’s infrequent and slow to develop
- Cross resistance does not develop with any other presently used antibiotics
How do tears defend the eye?
They contain IgA and lysozyme & provide lubrication
Describe IgA:
It’s a dimer. The secretory piece in the middle protects IgA from being degraded.
What type of immune defense does the conjunctiva have?
Lymphocytes, plasma cells, neutrophils, and mast cells that produce antibodies and cytokines
What is conjunctivitis?
Discharge, red eye, irritation, sensitivity to palpitation; caused by dilation and congestion of sub epithelial vessels
What are noninfectious causes of conjunctivitis?
Allergic rhinoconjunctivitis (hay fever), chemical reaction, prolonged use of ocular medications, neoplasm, irritation from contact lens or foreign body
Traits of Allergic conjunctivitis:
- Mostly bilateral
- Rarely has discharge
- Usually has redness
- No ear infection
- Very itchy/pruritic
Traits of Viral Conjunctivitis:
- 35% bilateral
- Discharge: mild, watery, sleepers
- Usually redness
- 10% have ear infection
- No itchiness
Traits of Bacterial Conjunctivitis:
- -50-74% bilateral
- Discharge is mucopurulent in younger children
- Redness common in older children but NOT younger
- 32-39% ear infection
- Not itchy but may rub eyes
What is the mechanism of hay fever/rhinoconjunctivitis (allergic)?
Hypersensitivity Type I
- Airborne allergen actives B cells
- B cells -> IgE
- IgE binds to surface of mast cell or basophil
- Another exposure to antigen
- antigen binds antibodies on mast cell
- Mast cell degranulates and releases histamine which causes inc. permeability and distention in blood capillaries (inflammation)
How do you treat Hay fever?
Antihistamines, mast cell stabilizers, non steroidal anti-inflammatory drugs
What should you avoid with hay fever?
- Antigen & glucocorticoid
- Steroids effective but can cause complications like glaucoma, cataract & 2ndary infections
What is the most common viral conjunctivitis in neonatal and post-natal?
Neonatal - HSV
Postnatal - Adenovirus (most common), Coxsackie A24, HSV 1 & 2, VZV (herpes zoster ophthalmic), EBV, rubella, mumps, influenza
Describe typical clinical presentation of viral conjunctivitis:
Recent upper resp. tract infection, preauricular adenopathy
- Benign and self limited in immune competent
- May see acute hemorrhagic conjunctivitis: blood vessel pops but general resolves on its own
How to treat viral conjunctivitis?
Cold compress and topical vasoconstrictors
What are the traits of adenoviruses?
- Non-enveloped
- dsDNA
- Lytic in epithelial cells and latent in lymphoid
- Highly contagious spread through fomites like swimming pools
- Has coxsackie receptor
- Conjunctivia - strains 19 & 37
What does the New AdenoPlus test do?
- Dab and drag on conjunctiva
- Detects adenovirus hexon protein part of viral capsid
What are the most common causes of acute bacterial conjunctivitis (mucopurulent) in children?
Staph. aureus, Streptococcus pneumoniae, Haemophilus influenzae
(not as often: Moraxella lacunata)
What are the most common causes of acute bacterial conjunctivitis (mucopurulent) in
adults?
Staphylococcus aureus (sometimes strep. pneumonia, strep, progenies and pseudomonas aeruginosa)
How to treat acute bacterial conjunctivitis (mucopurulent)?
Self-limited but may want to treat because it decreases morbidity and transmission
-Empiric treatment with gram + and - coverage
Trimethoprim and polymyxin ophthalmic drops
More expensive moxifloxacin drops
What is the mechanism of trimethoprim?
Bacteriostatic
- Inhibits bacterial dihydrofolate reductase (can’t make tetrahydrofolic acid for pyrimidines)
- Has low affinity for mammalian response
What is the mechanism for Polymyxin B?
Binds LPS in membrane creating holes ultimately leading got release of cellular contents
-Used for GRAM NEG., multi drug resistant
What causes hyper acute bacterial conjunctivitis?
Neisseria gonorrhoeae (less often N. meningitidis)
What does N. gonorrhoeae look like in the eye?
- Copious yellow-green discharge
- discharge covering eyes, red swollen
- Swollen lymph nodes
How to diagnose N. gonorrhoeae?
- Gram stain for gram -, intracellular diplococci
- Growth on chocolate agar supplemented with vancomycin, collision, nystatin & trimethoprim (non sterile site)
How to treat N. gonorrhoeae?
Promptly with SYSTEMIC ceftriaxone
-OR it can quickly cause corneal ulceration and perforation, can augment with topical antibiotics and irrigation
What is Ophthalmia neonatorum?
Conjunctivitis or keratoconjunctivitis (cornea too) in first few weeks of birth.
-N. Gonorrhoeae, C. trachomatis, Staphylococcus, Streptococcus, E. coli, H. influenzae or H. simplex.
How do you diagnose and treat Ophthalmia neonatorum?
Diagnose: cultures and smears
Treat: appropriate antimicrobial, often erythromycin
Prevent: prophylaxis with erythromycin ointment
What are the two types of Chlamydia trachomatis?
- Inclusion conjunctivitis (serotypes D-K)
- Trachoma (serotypes A-C)
- Coinfections should be considered - often N. gonorhoaea
What is important about Trachoma?
It is the leading cause of blindness worldwide due to multiple infections since no long lasting immunity
How do you diagnose Trachoma?
Direct fluorescent antibody
How do you treat Chlamydia trachomatis?
Systemic azithromycin & improve hygiene
Treat partners with widespread prophylaxis - being used to try to eliminate Trachoma by 2020
How does Chlamydia trachomatis spread?
Elementary body (EB) enters epithelial cells, converts to reticulate body (RB), and then replicates using binary fission
What form of Chlamydia trachomatis has a rigid outer membrane?
Elementary body (EB)
How does HSV-1 present in eye?
Keratoconjunctivitis (conjunctiva and cornea)
