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16. Eye Infection - Latin 101 Microbial Diseases of the...

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Unformatted text preview: Latin 101 Microbial Diseases of the Eye (Bacterial, viral and parasitic!) Blepharitis Conjuctivitis Keratitis Dacryocystitis Endophthalmitis Retinitis Normal Flora of the skin Organism Staphyloccus epidermidis Corynebacteria Propionibacterium acne S. Aureus Moraxella sp. Streptococcus pyogenes Enterobacteriaceae Blepharitis Inflammation of the eyelid or its margins Causes a burning/itchy feeling Multiple etiologies i.e. S. aureus Treated with topical antibiotics and improved local hygiene % incidence 85-100 8555 45-100 455-25 5-15 0-4 rare Hordelum (stye) stye) External: Involves the tiny sweat glands located near the eyelashes (Gland of Zeiss) Zeiss) Infection is localized Is painful, red Is frequently caused by S. aureus Resolves spontaneously Hordeolum (stye) stye) Internal: Infection of the Meibomian gland (located deep in eye lid and produces a fatty/oily substance called sebum) Is painful and can result in an abscess or cellulitis Frequently caused by S. aureus Best treated with oral antibiotics and drainage Conjunctivitis Inflammation of the conjunctiva Causes "red eye" Itching, burning, and a discharge Viral Conjuctivitis Most common form of conjuctivitis Usually caused by an adenovirus Highly contagious, spread by direct contact Causes red eye with a clear discharge, adenopathy, and follicle formation adenopathy, No specific therapy, but no school! school! Can have a viral or bacterial cause Bacterial Conjuctivitis Purulent discharge, danger of corneal ulceration Caused by: Children: Haemphilus influenzae Adults: Staphylococcal, Streptococcal, gonococcal Ophthalmia Neonatorum (ON) Infectious conjuctivitis in the first 28 days of life Acquired during passage through the birth canal Agent (%) Chlamydia 29 Gonoccal 15 Staphylococcal 10 Gonococcal and Chlamydia 1 Chemical 2 Unknown 43 Treated with topical antibiotics Gonococcal infection treated with i.v. or i.v. i.m. antibiotics i.m. ON due to Neisseria gonorrhoeae Most serious cause Usually appears 2-5 days after birth 2Marked bilateral purulence Rapidly leads to corneal ulceration and therefore produces high risk of blindness Acquired from the birth canal Can be prevented by putting silver nitrate or erythromycin drops in the neonate's eyes ON due to Chlamydia trachomatis Called "inclusion conjuctivitis" conjuctivitis" C. trachomatis is an obligate intracellular parasite Acquired from the birth canal Infection can spontaneously resolve, or it can lead to permanent scarring (trachoma) Erythromycin drops put in the neonate's eyes at birth Trachoma (C. trachomatis) Leading infectious cause of blindness worldwide! Causes conjuctivitis, corneal revascularization, conjuctivitis, scarring, scar retraction, corneal abrasions, corneal opacities Common in areas of poor hygiene (Africa, Asia, Native Americans in SW USA) Transmission is by direct contact or by flies Can be treated with oral erythromycin Infections of the cornea Inflammation of the cornea is referred to as keratitis and can produce corneal ulcers It is a sight threatening emergency and should be treated immediately to prevent blindness Frequently unilateral and produces blurred vision, a red, painful, photophobic and tearing eye. Infections of the Cornea Viral causes: herpes simplex I (topical trifluridine) trifluridine) Varacella zoster (systemic acyclovir) Acanthamoeba Keratitis Uncommon, about 200 cases/year Caused by a ubiquitous, free-living, fresh water amoeba freeRisk factors: Trauma Soft contact lens use Bacterial causes: Pseudomonas aeruginosa Associated with soft contact lenses (never use tap water to clean your contact lenses!!!) Fungal causes: Especially seen post trauma Amoeba can grow in contact lens cleaning solutions Don't swim with contacts in place! Causes severe damage that often requires a corneal transplant Endophthalmitis "infected eyeball" Exogenous: Caused by trauma, surgery, corneal perforation Antimicrobials and the Eye Routes of administration: Topical (well absorbed good blood supply) absorbed Subconjunctival injection Intravitreal injection Vitreous replacement fluid Systemic administration (i.v., eye/blood (i.v., barrier?) Endogenous: Bacterial sepsis (ie strep. Pneumonia) (ie Contiguous cellulitis CMV in HIV retinitis ...
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