Felton: eye infections Flashcards
What is Dacryocystitis?
infection of the lacrimal sac -Tear fluid collects in the lacrimal sac due to obstruction and bacteria from the conjunctiva wash into the sac and find a stagnant pool of fluid in which they multiply -symptoms: tearing and discharge - normally in infants and people >40 yo -
What are the 3 kinds of Dacryocystitis?
- Chronic adult dacryocystitis - tearing usually the only sign, but mucoid material can sometimes be expressed from the tear sac
- caused by S. pneumoniae or candida albicans.
- need to relieve obstruction - Acute adult dacryocystitis
- pus comes out
- usually S. aureus
- need to treat with antibiotics and warm compreses.
- need surgery - Infantile dacryocystitis
- failure to canalize of a nasolacrimal duct–> born with it.
- H. influenzae
- once duct is opened, infection will leave
What will you get when there is a blockage above the lacrimal sac?
Canaliculitis
Actinomyces israelii, Candida albicans, or Aspergillus species.
a secondary purulent unilateral conjunctivitis
-will see organisms on a gram-stained smear
What is orbital cellulitis? Location, symptoms, etiology, what can cause if untreated?
- involves the true orbit, behind the orbital septum. Very serious.
- Symptoms - swelling and redness of the eyelids, chemosis, exophthalmos (push eye forward), and dull pain, usually unilateral
- originates from the sinuses.
- etiology:
a) Pneumococci, other streptococci, staphylococci. b) Haemophilus influenzae b in unvaccinated children under 3.
c) Fungi - Mucor and Rhizopus (Phycomycosis) in patients with acidosis such as uncontrolled diabetics, and in the immunocompromised - entry: direct extension from sinuses or through vascular channels between orbital contents and sinuses
- -> can lead to brain abscesses if not treated.
What is preseptal cellulitis?
- infection of the subcutaneous tissue of eyelids anterior to the orbital septum.
- away from the eye==> less serious than orbital cellulitis
- usually < 5 yo
- Extension of skin infection: Staphylococcus aureus or Streptococcus pyogenies
- From traumatic injury - Staphylococcus aureus
How do the natural defenses fight conjunctivitis?
- Flushing action of tears
- -> lids wipe away (mechanical) - Chemical composition of tears
a. Lysozyme
b. Secretory IgA, also IgG
c. Lactoferrin sequesters iron - Lymphocytes within conjunctiva
- exfoliation of the conjunctival epithelium
What are the sign and symptoms of conjunctivitis?
- Foreign body sensation
- scratching/burning sensation
- sensation of fullness around the eyes
- itching (usually means allergic)
- hyperemia (red eye) -> peripheral redness (doesn’t come to the cornea–> limba is NOT red)
- tearing
- exudate
- edema (sometimes)
- papillary or follicular hypertrophy (sometimes)
- can show pseudomembrane
How is conjunctivitis normally diagnosed?
Usually just a history and exam
can culture the conjunctival exudate or by scraping with a sterile platinum spatula from anesthetized conjunctival surface –> gram stain (bacterial type), giemsa stain and wet mount (fungi)
What will the stains produce for each of the conjunctival scraping? (normal, acute, chronic, viral, allergic, chlamydial)
Normal eye - epithelial cells and occasional goblet cells.
Acute bacterial infection - large numbers of neutrophils, with bacteria inside or outside the cells.
Chronic bacterial infection - decrease in neutrophils and increase in lymphocytes and large mononuclear cells.
Viral conjunctivitis - lymphocytes and monocytes are predominant. In herpes simplex infections, multinucleated epithelial cells may be seen. Intranuclear inclusion bodies in epithelial cells reflect DNA viruses. (If a pseudomembrane is present, there may be a predominance of neutrophils.)
Chlamydial infections - basophilic intracytoplasmic inclusion bodies seen in epithelial cells. In early stages, exudate rich in neutrophils and containing plasma cells is seen.
Allergic conjunctivitis - scrapings characteristically reveal eosinophils. –>Perform culture and antibiotic sensitivity tests
What organisms cause acute catarral (non-purulent discharge) conjunctivitis?
- Streptococcus pneumoniae - most common cause in adults and children
- Haemophilus aegyptius and Haemophilus influenzae (frequent cause in children).
- Staphylococcus aureus - most common cause in the newborn; fairly rare otherwise.
- Occasionally viridans streptococci, Escherichia coli and Proteus sp.
What normally causes acute purulent conjunctivitis? What complications can happen with it?
Neisseria gonorrhoeae
May progress to severe corneal damage and diffusion of toxic products through the cornea into the anterior chamber where they may cause toxic iritis. If the cornea perforates, it can lead to endophthalmitis and panophthalmitis. In newborn, infection occurs during passage down infected vagina of mother; in older individuals, it is an occasional complication by contamination from acute gonorrheal urethritis, or vaginitis.
What is the most common cause of chronic bacterial conjunctivitis?
- Staphylococcus aureus is most common in adults, where it may develop into chronic marginal blepharitis or epithelial keratitis involving the lower half of the cornea.
- mixed infections
- Pseudomembranous or Membranous Conjunctivitis, which may cause conjunctival scarring
- -> Cornyebacterium diphtheria, Streptococcus pyogenes
What can chlamydia cause?
- Trachoma: a chronic follicular conjunctivitis - one of the commonest of all chronic human diseases. Rare in the U.S. except among Native Americans in the southwest
- -> most common cause of preventable blindness
- caused by Chlamydia trachomatis antigenic types A-C.
What can Chlamydia trachomatis antigenic types D through K cause in the eye?
- Inclusion Conjunctivitis (Inclusion Blennorrhea)
- chlamydia grows in vacuoles in inclusions
- -> secondary infection from a genital STD.
- non-chronic
- doesn’t lead to blindness
What will a chlamydial stain show?
vacuoles and inclusion bodies
