Eye and Ear Infections – Flashcards

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question
How is the eye normally protected from infection?
answer

Conjunctiva=mucosal surface on eyelid and cornea

What is present on all mucosal surfaces?

IgA=neutralization and opsinization

Lysozyme=disrupt bacterial cell wall

Normal bacterial flora=Staph epidermis, Corynebacteria xerosis

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3 types of common eye infections
answer

Blepharitis

Conjunctivitis 

Keratitis

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Blepharitis-basics
answer

bacterial cause

S. aureus

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Conjunctivitis-basics
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"pink eye"

inflammation of conjunctiva

Viral OR bacterial

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Keratitis-basics
answer

inflammation of cornea

vision threatening

Viral (HSV) OR parasitic

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Keratoconjunctivitis-basics
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conjunctiva and cornea

Viral (Adenovirus, Chlamydia)

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3 organisms with IgA protease
answer

SHIN

 

Strep pneumoniae

H. influenziae

Neisseria

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Gram positive organisms that cause eye infections
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Staph aureus

Staph epidermis

Strep pyogenes

Strep pneumoniae

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gram negative bacteria causing eye infecitons
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H. influenziae

Neisseria gonorrhoeae

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Viruses causing eye infections
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Adenoviridae

HSV 1

VZV

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Parasites causing eye infections
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Acanthamoeba

Onchocerca volvulus

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Blepharitis

-causative agent

-symptoms

-lesser causes

answer

-S. aureus

-itching, burning, redness, CRUSTING OF EYELASHES

-HSV, VZV, Phithiris pubis

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Stye
answer

Hordeolum

-infection of tear gland, sebatious gland, hair follicle

-caused when blepharitis becomes an ACUTE LOCALIZED infection

-S. aureus

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Staph aureus

basics

answer

coag + (destroy H2O2)

cat +

B-hemolytic

mannitol fermentation

highly RESISTANT to penicillin

 

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Distinguish btw staph and strep
answer

Staph=CAT POSITIVE

Strep=CAT NEGATIVE

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Difference btw Staph aureus and Staph epidermis
answer

S. aureus=COAG POSITIVE

Staph epidermis (and all other Staph)=COAG NEGATIVE

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S. aureus

virulence

answer

Fibronectin binding protein (adhere to conjunctiva)

Protein A (prevent opsinization)

Coagulase (walls off the bacteria)

Alpha toxin (B-hemolytic)

 

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B-BRAS
answer

Bactitracin

Group B Strep=Resistant

Group A Strep=Sensitive

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Bacterial Conjunctivitis

-causes

answer

Staph epidermidis

Strep pyogenes

Strep pneumoniae

H. aegyptius

 

(Staph aureus not so much)

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Bacterial conjunctivits vs. Viral conjunctivits
answer

Bacterial=acute onset

purulent discharge

pruritis MAYBE

 

Viral=subacute onset (usually occurs after an URI or with an URI

clear, watery discharge

pruritis COMMON

 

Both=red eye

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Bacterial conjunctivitis

-diagnosis and treatment

answer

history and physical

gram stain

topical antibiotic ointment

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Staph epidermidis

-basics

-virulence

answer

Coag NEGATIVE

novoviocin sensitive

opportunistic (catheters and prosthetics)

 

Virulence=BIOFILM (surround organism and prevents against phagocytosis, complement, antibiotics)

question

Streptococcus

-group characteristics. How do you classify them?

answer

gram + cocci

Chains

facultative anaerobes

non-motile

 

Classify by:

hemolytic pattern

Lancefield antigens

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Strep pyogenes

-basics

-habitat

-transmission

answer

gram + cocci

chains

Group A (B-BRAS)

B-hemolytic

 

Habitat=nares, URT, skin

 

Transmission=respiratory secretions

directs contact with infected skin lesions

 

question

Strep pyogenes

-virulence

answer

M protein

Protein F

Protein G

C5a peptidase, IgA protease

Hyaluronidase, DNAses

Streptolysins=O and S (oxygen labile and stabile)

Exotoxins=A-C

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Strep pneumoniae

-mnemonics

 

answer

MOPS

most common cause of: Meningitis, Otitis media, Pneumonia, Sinusitis

Most OPtochin Sensitive

 

PPP

Pairs

Polysaccharide capsule

Pneumolysin

question

Strep pneumoniae 

-basics

-virulence

answer

gram +

alpha-hemolytic

PAIRS

NO lancefield antigens

optochin

 

Virulence=polysaccharide capsule

enzymes (autolysin and pneumolysin)

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H. aegyptius

-basics

-virulence

answer

gram - bacilli

facultative anaerobe

requires Chocolate agar with NAD and Factor X

it is H. influenziae, but NON-encapsulated

 

Virulence

IgA protease 

biofilm

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2 bacteria that have BIOFILM
answer

Staph epidermidis

H. aegyptius

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Neonatal bacterial conjunctivitis

-causes

-transmission

answer

Gram - bacteria:

chlamydia trachomatis

Neisseria gonorrhoeae

 

Transmission=during passage through the birth canal

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Neisseria gonorrhoeae

-basics

-virulence

answer

gram - 

non-motile

oxidase positive

aerobic

ferments GLUCOSE only

NON-encapsulated

 

Virulence

Pili (antigenic variation)

LPS (sialic acid)

IgA protease

outer memb proteins

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Gonococcal diseases (3)
answer

1. gonorrhea

2. conjunctivitis

3. opthalmia neonatorum

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Opthalmia neonatorum

-cause

-basics

answer

Nesseria gonorrhea

 

purulent bacterial conjunctivitis

transmitted to neonate during vaginal delivery

occurs 3-5 days after birth

corneal involvement is possible-->blindness!

may be invasive--rhinitis, arthritis, meningitis

 

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Group Chlamydiae
answer

resembles gram negative=high lipid content, NO peptidoglycan, penicillin binding proteins, lysozyme resistant

 

NOT identifiable in gram stain

use immunoflourescence

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Chlamydia trachomatis

-transmission

-major diseases (serovars)

-pathogenicity

answer

Transmission=person to person or mother to child

Diseases:

1. Trachoma (A-C)

2. STD (D-K)

-inclusional conjunctivitis and pneumonia (INFANTS)

3. Lymphogranulmoa venerum (L)

 

Pathogenicity=can form EBs

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Chlamydia trachomatis and infants
answer

Serovars D-K (STD)

 

Inclusional Conjunctivitis (ICN)

2-14 days

conjunctiva inflammation with purulent yellow discharge

prophylactics

treat systemically to prevent pneumonia

 

Pneumonia

2-12 weeks

rise in IgM titre

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Viral conjunctivitis

-causes

answer

Adenovirus=most common

HSV 1=progress to keratitis

VZV=following primary or secondary disease

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Adenovirus
answer

non-enveloped virus

common following URI

transmitted by respiratory secretions, fomites, and contaminated swimming pools

 

self limiting, NO antivirals

may progress to kerato-conjunctivitis

 

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Keratitis

-disease 

-clinical presentation

-most common agents that progress form conjunctivitis to keratitis

answer

proliferation of microorganisms in the stroma of the cornea-->causes ulcers, necrosis, accumulation of immune cells, initiate avascular changes in the cornea-->vision threatening

 

presentation

-pain, photophobia, blurred vision, redness

 

Progress=S. pneumoniae, H. aegyptius

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Most common cause of Keratitis?
answer
HSV 1
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HSV 1

 

answer

enveloped

DS DNA

transmitted by direct contact with virus-containing secretions or mucosal/skin lesions containing the virus

Trigeminal ganglion-->reactivation

 

common cause of BLINDNESS

 

lesion manifests as a VESICLE

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Acanthamoeba
answer

Common in U.S.

Protozoan (cyst and trophozoite)

 

acquired by direct contact

can survive in water sources

 

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Greatest risk factor for acquiring keratitis?
answer
contact lens wearers
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2 presentations of Acanthamoeba
answer

1. Keratitis and ulceration of cornea

-pain, photophobia, foreign body sensation

 

2. Chronic granulomatous amebic encephalitis 

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Onchocerca volvulus

-basics

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Nematode

cause onchocerciasis=River blindness

 

transmitted by Black Fly

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Onchocerca volvulus

-how worm spreads

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black fly bites you-->larva migrates through tissue-->develops into adult worm-->adult worms group together (2-3)-->encapsulate into BENIGN fibrous nodules-->they are mating and releasing thousands of microfilariae everyday-->River blindness bc the microfilariae get to the cornea
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Symptoms of Onchocerca volvulus
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dermatitis/pruritis

skin losses elasticity-->wrinkled

eye lesions-->blindness

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Keratoconjunctivitis

-cause

answer

Chlamydia trachomatis (A, B, Ba, C)

 

Asia, Africa, Mediterranean

-usually infected at age 2, then repeatedly cause infection throughout life

 

Leading cause of preventable blindness

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Keratoconjunctivitis

-presentation

answer

early=inflammatory changes in conjunctiva and cornea

FOLICULAR CONJUNCTIVITIS-fibrosis of eyelid causes it to curl up-->eyelashes abrade the eye's conjunctiva

;

late=re-infection

-corneal abrasions, scarring, blindness

;

;

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Trachoma

-diagnosis

answer

based on clinical appearance;

develop group-specific and serovar-specific antibodies=found in serum and eye secretions

;

PCR

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External ear infection
answer

S. aureus

-folliculitis/furunculosis (hairs are infected)

-acute, local infection

-abscess formation associated with hair in ear canal

;

P. aerunginosa

-swimmer's ear

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Diffuse Otitis Externa
answer

most commonly caused by P. aerunginosa

-develops a moist and elevated pH environment (nice for organism to live)

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Pseudomonas aeruginosa

-basics

answer

gram -

aerobic

motile

oxidase +

produces PYOCANIN and SWEET GRAP ODOR

opportunistic=CF patients

Antibiotic resistant

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P. aeruginosa

-virulence

answer

extracellular slime

 

Exotoxin A=ADP-ribosylates EF 2, block protein synthesis, cell death!!

Elastase=inactivates IgA, IgG and several complement components. Targets elastin in lungs and BVs

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Otitis Media
answer

inflammation of middle ear

follows URI

more common in kids bc of eustachian tube

 

common causes: RSV, influenze, parainfluenza

Strep pneumoniae

H. influenze-Type B

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