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MICRO
Eye/Ear Infections
47
Microbiology
Graduate
05/16/2011

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Term
Iga defense mechanism
Definition
Neutralization and Opsonization at mucosal surfaces
Term
Lysozyme
Definition
cleaves glycosal bonds in the peptidoglycan bacterial cell wall
Term
normal bacterial flora
-staph epidermidis
-c. xerosis
Definition
provide defense by competing with the pathogen
Term
Blepharitis
Definition
-Inflamation of the Eyelid
-caused by S. Aureus usually
-may be caused by HSV, Varicella or Phthiris Pubis
-often chronic due to poor hygiene
Term
Conjunctivitis
Definition
"Pink- eye" can be both bacterial and viral
Term
Keratitis features
Definition
-Infection of the cornea w/ ulcers and necrosis
-can cause blindness due to accumulation of immune cells
-caused by HSV or a parasite or following corneal trauma or contact lenses
Term
Keratoconjunctivitis
Definition
-Infection of the conjunctiva and cornea
-caused by Adenovirus and Chlamydia
Term
Blepharitis sx's
Definition
-itching, burning, redness and crusting of the eyelashes
Term
Complication of Blepharitis
Definition
-Stye/Hordeolum: acute localized infection of the tear gland, seb gland or hair follicle
Term
S. Aureus distinguishing features
Definition
-Gram + cocci
-CAT POSITIVE
-COAG POSITIVE (differentiates from other staph, allows abscess formation)
-Beta hemolytic
-mannitol fermentation
-resistant to penicillin!
Term
S. Aureus virulence factors
Definition
-Protein A (binds to Fc of IgG preventing opsonization)
-Coagulase
-Fibronectin Binding Protein
-Alpha toxin (lyses cells)
Term
Bacterial Conjunctivitis distinguishing features
Definition
-Acute onset
-Purulent Discharge
-Pruritis
Term
Bacterial agents causing Conjunctivitis
Definition
-S. Epidermidis
-S. Pyogenes
-S. PNA
-H. Aegyptius (gram -)
Term
Bacterial Conjunctivitis Dx and Tx
Definition
-Hx and PEx
-Gram Stain
-Topical Abx
Term
S. Epidermidis distinguishing features
Definition
-COAG NEGATIVE (like all staph except Aureus)
-Novobiocin sensitive
-normal flora of skin
-Has Biofilm (protects against complement and phagocytosis)
Term
Streptococcus group features
Definition
-Gram + cocci in pairs or chains
-facultative anaerobes
-non-motile
-CAT negative
-classified by alpha/beta/gamma
-Lancefield Ags
Term
S. Pyogenes distinguishing features
Definition
-pairs or chains
-group A has A Ag
-beta hemolytic
*susceptible to bacitracin
-lives in nares, URT and skin
Term
S. Pyogenes virulence factors
Definition
-M Protein and Protein F (binding to conjunctiva)
-Protein G (prevents opsonization)
-c5a peptidase and IgA protease
-Streptolysins O and S
-exotoxins SPEA
Term
S. PNA distinguishing features
Definition
-No Lancefield Ags
-Alpha hemolytic
-grows in pairs (cocci)
-Optochin sensitive
Term
S. PNA virulence factors
Definition
-Polysaccharide capsule
-Autolysins (in cell wall)
-Pneumolysins (in cytoplasm)
Term
H. Aegyptius (Influenzae) distinguishing features
Definition
-Gram negative bacilli
-facultative anaerobe
-grows on Choc Agar w/ NAD and Factor X
-non-encapsulated
Term
H. Aegyptius virulence factors
Definition
-IgA Protease
-Biofilm
(does NOT cause PNA or otitis media!)
Term
Neonatal Bacterial Conjunctivitis (Purulent) AKA Opthamlmia Neonatorum
Definition
-presents during first month of life (3-5 days post birth usually)
-caused by N. Gonorrhea or Chlamydia Trachomatis
-can lead to blindness or systemis illness
-tx w/ erythromycin ointment
Term
N. Gonorrhoeae distinguishing features
Definition
-Gram negative diplococci
-non motile
-Oxidase positive
-Aerobic (increase Co2)
-ferments GLUCOSE only
-NON encapsulated
Term
N. Gonorrhoeae virulence factors
Definition
-Pili/adherence-antigentic variation and phase variation; urethral, vaginal, recta, conjunctival epithelium)
-lipooligosaccharide
-Sialic acid- mimics RBS's
-IgA Protease
-OMP's for attachement
Term
Chlamydiae distinguishing features
Definition
-leading cause of preventable blindness
-intracellular parasite (can't make ATP)
-grows in inclusion bodies
-cell wall looks Gram Neg.
-need to identify w/ immunofluorescence
-has group specific Ag
-transmitted by contact and flies
-3-10 day incubation
Term
C.Trachomatis Distinguishing features
Definition
-causes Trachoma (serotype A-C)
-causes STDs leading to inclusional conjunctivits and PNA in infants
-causes Lymphogranuloma Venereum
Term
Neonatal Conjunctivitis (ICN)
Definition
-sxs begin 5-14 days post birth in 20-50% of newborns with infected mothers
-conjunctival inflammation with purulent YELLOW d/c
-tx systemically to prevent PNA x 6 mo.
Term
Viral conjunctivitis sx's
Definition
-acute OR subacute onset (more often)
-clear, watery d/c
-pruritis common
-often post URI
Term
Viral conjuntivitis causes
Definition
-Adenovirus (esp in kids)
-HSV1 (chronic, can progress to keratitis)
-VZV
Term
Adenovirus distinguishing features
Definition
-non enveloped virus
-transmitted by respiratory secretions, fomites and contaminated pools
-self limiting virus
-may progress to kerato-conjunctivitis
Term
Keratitis sx's
Definition
-Pain
-Photophobia
-Blurred Vision
-Redness
Term
HSV1 distinguishing features
Definition
-enveloped virus
-replicates in conrean epithelium
-estbs latency in tirgeminal ganglia
-one of the most frequent causes of blindness and conjunctivitis in the US
Term
Parasitic Eye Infection Causes
Definition
-Acanthamoeba (Protozoan)
-Onchocerca Volvulus (Helminth Nematode)
Term
Acanthamoeba distinguising features
Definition
-Protozoan (cyst in environment and trophozoite in pt)
-found in fresh, brackish, and salt water, humidifiers, soil and dust
-aquired by direct contact, swimming or via contacts
-common in US
Term
Keratitits and corneal ulcers caused by Acanthamoeba sx and dx
Definition
-FB sensation
-Severe pain
-Photophobia
-can dx by presence of trophozoits/cysts in corneal scrapings
Term
Chronic Granulomatous Amebic Encephalitis (subacute)
Definition
-caused by Acanthamoeba
-common in chronically ill
-sxs for several weeks with a HA and AMS
Term
Filarial Worms general features
Definition
-long/thread-like
-inhabit lymph system and sub Q tissue
-eggs are long and thin- microfilariae
Term
Onchocerca Volvulus distinguishing features/mode of infection
Definition
-transmitted by Black Fly (in Africa mostly)
-causes 'River Blindness'
-fly bites host and injects larval form, adult worms develop and group together, form a fibrous nodule (mate inside and release 1000's of microfilariae p/day), eggs migrate into cornea, leave nodules on trunk, limbs and head while migrating
-vascular changes in eye causing inflammation and blindness
Term
Onchocerca Volvulus sx's
Definition
-dermatitis/pruritis
-skin looses elasticity (wrinkled)
-eye lesions/blindness
Term
Trachoma sxs
Definition
-caused by C. Trachomatis
-early: inflammatory changes in cornea and mucopurulent d/c
-late/re-infections: corneal abrasions, scarring, eyelid deformities and blindness
-keratoconjunctivitis
Term
Trachoma dx
Definition
-clinical appearance (follicles under eyelid)
-group specific serovar testing from eye secretions and blood
-immunofluorescence
-PCR based assay
Term
Folliculitis/Furunculitis
Definition
-External Ear infection caused usually by S. Aureus
-acute/focal abscess formation in hair follicle
Term
Diffuse Otitis Externa
Definition
-Swimmer's ear
-diffuse external ear infection
-develops as a result of excessive moisture and elevated pH which is hospitable to P. Aerunginosa
Term
P. Aerunginosa distinguishing features
Definition
-Gram Negative Bacilli
-Aerobic
-Motile with single flagella
-Oxidase positive
-Sweet/grape odor-opportunistic- CF pts
-live in the environment, can colonize URT and GI tract
Term
P. Aeruginosa virulence factors
Definition
-Extracellular Slime; alginate
-Hemolysins
-Exotoxin A (causes local effects only- cell death)
-Elastase: inactivates IgA, IgG, complement and targets elastin in lungs and BV
Term
Otitis Media features
Definition
-follows URI, common in kids
-often caused by various viruses, S. PNA,
H. Influenzae Type B
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