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Micro240 > Eye and Ears > Flashcards

Eye and Ears Flashcards

1
Q

is the eye sterile if no what is the normal flora

A

no

Normal flora is limited to Staphylococci (that are not S. aureus), Diphtheroids, Propionibacteria, Viridans streptococci & Micrococcus

also suspecttible to transient bacteria
like in dental surgeries and you bled a little and bacteria got in

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2
Q

how does the eye fight infections

A

Tears
-flushes foreign particles
-has antibacterials like
Lactoferrin - binds iron to prevent organism metabolism
Lysozyme - breaks down peptidoglycan & destroys cell wall
Lipocalin, & beta-lysin -breaks down org cell membrane
IgM, IgG & IgA- tag pathogens to be removed, stop them from adhering and neutralize toxins

Corneal Epithelial Cells- cytokine secretion activates immune response , regulate immune system by releasing complement

neutrophils, eosinophils, macrophages, NK & T-cells, cytokines, complement.

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3
Q

Uveitis

A

Eye inflammation of tissue in the middle of the eye bwtn sclera and retina
-types of uveitis classified by what eye parts are inflamed
-caused by infection , injury or autoimmune

Symptoms
Decreased vision, ocular ache, redness, photophobia, and floaters.
Can lead to vision loss

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4
Q

common causes of bacterial uveitis

A

S. aureas
Strepto
Enterobac
Listeria

more common

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5
Q

Anterior Uvetis

A

affects the iris

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6
Q

Intermediate Uvetis

A

affects focusing and vitreous

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7
Q

Posterior uvetis

A

affects part of eye that attaches retina to white of eye

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8
Q

panuveitis

A

affects all of eye from front to back

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9
Q

Conjunctivitis

A

pink eye

Inflammation of transparent membrane (conjunctiva) that lines inner eyelid & covers white part of eye

-redness, tearing, itchiness, gritty feeling, pus discharge.
-caused by viral or bacterial infection – very contagious.
-can be caused by allergies
-in babies due to half opened tear duct

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10
Q

Viral conjunctivitis:

A

most common cause of pink eye
Adenovirus, HSV, VZV, COVID-19

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11
Q

Bacterial conjunctivitis:

A

. aureus, S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis or, less commonly, N. gonorrhoeae (STI), Chlamydia (STI)

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12
Q

Fungal conjunctivitis: very rare

A

Candida spp. after topical corticosteroid & antibacterial treatment
Paracoccidioides, Coccidiodes immitis, Blastomyces in immunocompromised

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13
Q

Parasitic conjunctivitis: very rare

A

Loiasis, Dirofilariasis – parasitic worms

tropical

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14
Q

Chlamydia trachomatis CONJUNCTIVITIS

three types

different serovars type for a different type

A
  1. Trachoma -Serovars A, B, Ba, and C: based on differences in cell wall or membrane
    Preventable blindness of infectious origin.
    Person-person by contact with infected eye discharge - children, crowded houses, improper households
  2. Adult Inclusion conjunctivitis -Serovars D-K
    Chronic follicular conjunctivitis -transmitted sexually or from hand-to-eye & rarely, eye-eye from sharing makeup

3.. Neonatal conjunctivitis (also called Ophthalmia neonatorum - Serovars D-K
-mom’s genitals to baby during birth
-Second most common cause is N. gonorrhea.

DONT NEED TO KNOW SEROVARS

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15
Q

Chlamydia’s Infectious Cycle and its forms

A

Anaerobic, obligate intracellular bacteria
cant make ATP or synthesize AA

Early - Conversion of EB into RB
Midcycle - Replication of RBs
Late- Conversion of RBs into EBs

Elementary body (EB): Non-replicating, infectious particle released from infected cells.
Transmission form – human- human or sometimes bird-human
Reticulate body (RB): Intracytoplasmic form that replicates new EB.. replicating non infectious form

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16
Q

DIAGNOSTIC TESTS FOR CHLAMYDIA

A

Giemsa stain: intracytoplasmic epithelial inclusion bodies of conjunctival scraping

Direct immunofluorescent (DFA) stain of conjunctival scrapings

Culture of conjunctiva - use cell lines to grow

Serology like Enzyme-linked immunosorbent assay to detect serum IgG titers to Chlamydia

GOLD - Molecular like NAAT

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17
Q

GONOCOCCAL CONJUNCTIVITIS

A

-Eye exposed to infected genital secretions from person with genital Gonorrhea
-if not treated leads to meningitis and/or blindness
-Ophthalmia neonatorum (newborn eye infection with GC, Chlamydia, or HSV).
-before we treated with prophylaxis (silver nitrate drops, erythromycin ointment at birth but now we screen and treat pregnant moms

can lead to disseminated infection
like sepsis
meningitis

18
Q

Retinitis

A

Inflammation of retina, may lead to blindness.
-mostly in immunocompromised
-caused by Toxoplasma, Cytomegalovirus, Herpes zoster, Herpes simplex, and Candida
-Organism transmitted by direct invasion or via blood
-can be genetically inherited disease: Retinitis pigmentosa

19
Q

Keratitis

A

Inflammation, ulceration or irritation of cornea
-caused by injury, foreign body or UV light , not wearing contacts properly - too long or dirty
-damages corneal epithelial = ulcers
Pseudomonas & S. aureus are most common bacterial causes
-Mycobacteria or fugus like candida, asp
-Viral HSV & parasite called Acanthamoeba.

20
Q

ACANTHAMOEBA and what to test with

A

-protozoan parasite found in water & soil.
-causes skin, central nervous system & eye (keratitis).
-associated with wearing contact lenses while swimming or washing lenses with tap water
-can lead to blindness
-cornea gets an opaque ring

test
Corneal scraping or biopsy -most reliable
Giemsa or Direct fluorescence
Culture of corneal scrapings or biopsy
PCR

21
Q

Blepharitis:

A

Inflammation along edges of eyelids.
Bacteria: S. aureus most common, other skin flora as well s epi, propinobac
Viruses: HSV (HSV 1 & 2)
Fungi: Candida albicans
Parasites: Eye lash mites, Lice

22
Q

Stye:

A

infection of small glands near base of eyelashes.
Most often caused by S. aureus.

23
Q

SPECMENS FOR EYE INFECTIONS

A

Conjunctival or eyelid swab (at michener)
Corneal scrapings/biopsies (sterile specimen)
Intraocular aspirates (sterile specimen)
Lacrimal secretions
If for virus, chlamydia/mycoplasma placed in UTM
Scrapings/biopsies/aspirates placed in sterile empty container
Swabs placed in Amies (has charcoal to absorb toxins - better for fastidious) or Stuarts (clear) transport media (not the best because you can take up resident flora)

24
Q

EYE SPECIMEN PROCESSING
Direct Specimen Stains

A

Gram
Giemsa
ELISA/Fluorescence

25
Q

EYE SPECIMEN PROCESSING
Culture:

what do we get at michener

A

Non-sterile specimens plated to BA & CHOC rein for 48
-NYC or TM (350C CO2) 72hrs if GNDC seen or if dr wants or neonate <1 wk old

Sterile specimens plated to BA, CHOC, CNA, MAC, BRUC & THIO (add NYC or TM if required)

we just conjunctival swab
direct report with quantitation the presence of pus cells, epithelial cells and organisms

26
Q

PATHOGENS IN EYE SPECIMENS

A

S. aureus
H. influenzae
BHS
Moraxella
Neisseria gonorrhoeae
Streptococcus pneumoniae
Pseudomonas aeruginosa
Enterobacterales

Are pathogens only if growing in pure/predominant #’s:
Enterococcus spp.
S. lugdunensis

27
Q

SUSCEPTIBILITY TESTING/REPORTING FOR EYE SPECIMENS

A

AST not usually done as most treatment is topical

set up an OX screen for any S. aureus & a VANC screen for any Enterococcus to rule out MRSA/VRE

AST will be performed & reported if specimens received were more invasively collected, i.e., tissue or fluids, because treatment will be intravenous instead of topical.

28
Q

NON PATHOGENIC FLORA IN EYE SPECIMENS
non sterile (OE) vs sterile samples (OM)

A

non sterile -Viridans strep, Diphtheroid, Micrococcus CoNs or non- pathogenic Neisseria
do minimal testing and report as normal flora

sterile - do full work up DO NOT REPORT AT NF

29
Q

ADDED PROCEDURE FOR EYE SPECIMENS GC INVESTIGATION

A

-Perform oxidase on any colonies growing on either CHOC or TM to rule out GC.
-If oxidase neg, is not GC, re-incubate both CHOC & TM for up to 72 hours.
-If oxidase positive, perform Gram stain.
If GNDC then perform ID tests.

ID of this organism must be by 2 different principles i.e., Biochemical + mass spectrometry or biochemical + serological.
At Michener we will be using MALDI & Bacticard.

-MALDI done first - If ID is not GC, stop there & re-incubate CHOC & TM for up to 72 hours
-If pos for GC, then set up Bacticard (can only be done from selective media TM/NYC).
-Requires a 2mcFld - if colonies too small, or growth too scant D2, subculture from TM to chocolate agar.
-If both MALDI & Bacticard indicate a GC: perform a Beta lactamase test.
-If no GC by D3, write you would re-incubate CHOC & TM for another day.

30
Q

OUTER EAR INFECTION
OTITIS EXTERNA (OE)

cause and symp

A

Superficial infection of skin of outer ear & outer ear canal (also called “Swimmer’s ear”).

cause
trapped moisture causes bacteria to grow
-using a q tip too hard that it causes trauma to ear canal

symp
Red, weepy, sensitive skin; bleeds easily.
Itchy & painful ear canal.
Sometimes fluid drainage

31
Q

NECROTIZING or MALIGNANT OE

A

complication of OE - rare
-bacteria from external ear infection gets to temporal bone of skull
-causes nerve damage/paralysis and sigmoid sinus clots.
-50% mortality rate
-in immunocomps and old ppl with diabetes
P. aeruginosa is most common cause followed secondly by S. aureus.
Aspergillus spp & Candida are most common fungus.

32
Q

Candida auris
germ tube?
type of pathogen
issue?
risk factor

A

-related to Candida albicans - GT neg
-Nosocomial pathogen – causes outbreaks in healthcare settings.
-Causes wound, ear & severe invasive infections with high mortality (57%).
-becoming multidrug resistant - problem
-need Infection control to stop transmission

at risk
-ppl after surgery or with central venous catheter
-ppl with diabetes or those treated with ABtic or Antifungal

33
Q

PROBLEMS WITH C. auris IDENTIFICATION

A

-hard to ID
-very drug resistant compared to Candida
-molecular is only reliable but not all hospitals have
-need to do susceptibility against antifungals
-once isolated we need to tell Infection control

34
Q

ASPERGILLUS OTOMYCOSIS

A

-Superficial fungal infection of external ear canal with Aspergillus
-in ppl who swim, use oil in ear, ABtic ear drop, steroids or immunocomp
-itchy, pain, feeling of blockage
-green or black fuzzy growth in ear
-Can also cause necrotizing or malignant otitis externa with local spread to bone & cartilage.

front - color and texture
back - color

35
Q

MIDDLE EAR INFECTION
OTITIS MEDIA (OM)

A

infection of air-filled space behind eardrum
-caused by virus/bacteria, cold, allergies
-happens at any age but most from 3 mot- 3 years because eustachian tube is immature and not functioning

symptoms
pain, red bulging ear drum , fever, hearing loss
-once the ear drum ruptures pus can drain from ear but the infection can spread to outer layer of CSF = meningitis

36
Q

SPECIMEN FOR OM

A

Tympanocentesis fluid - sterile
-Special needle with tube attached used to collect fluid from behind eardrum.
-sterile not NF
-cant use ear swabs

looking for any specimen

37
Q

ORGANISMS CONSIDERED PATHOGENS IN OM

A
38
Q

OE SPECIMEN PROCESSING

A

Outer ear swab in transport media– not sterile
-Direct specimen gram:
Quantitate and report: pus, epithelial cells, organisms
-culture BA, CHOC, CNA, MAC all 48hrs
-report and phone everyday

39
Q

PATHOGENS IN OE CULTURE

A

Pseudomonas aeruginosa (may cause malignant OE)
Staphylococcus aureus (may cause malignant OE)
Yeast
BHS
Enterobacteralis
Enterococcus & S. lugdunensis if in pure or predominant #s

Other pathogens more common in children
Streptococcus pneumoniae
Haemophilus influenzae

40
Q

SUSCEPTIBILITY TESTING FOR OE

A

not usually done as most treatment is topical

You must still set up an OX screen for any S. aureus & a VANC screen for any Enterococcus to rule out MRSA/VRE.

41
Q

OM SPECIMEN PROCESSING

A

Specimen: Tympanocentesis fluid/aspirate–sterile

Direct specimen gram:
Quantitate and report: pus, & organisms (not epithelial)

Culture BA, CHOC, CNA MAC, BRUC, THIO
REINCUBATE ALL BUT MAC

42
Q

WORK UP OF TYMPANOCENTESIS CULTURE

A

Sterile specimen so any growth followed up.
Perform testing until can determine whether organism is pathogen or not.
-AST (if applicable)- see common
-Send report & phone physician with results each day until specimen is complete.
You may also have to phone ICP or MOH depending on organism.

Micro240 (7 decks)

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