Eye and Ears Flashcards
is the eye sterile if no what is the normal flora
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
how does the eye fight infections
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.
Uveitis
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
common causes of bacterial uveitis
S. aureas
Strepto
Enterobac
Listeria
more common
Anterior Uvetis
affects the iris
Intermediate Uvetis
affects focusing and vitreous
Posterior uvetis
affects part of eye that attaches retina to white of eye
panuveitis
affects all of eye from front to back
Conjunctivitis
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
Viral conjunctivitis:
most common cause of pink eye
Adenovirus, HSV, VZV, COVID-19
Bacterial conjunctivitis:
. aureus, S. pneumoniae, Haemophilus influenzae, Moraxella catarrhalis or, less commonly, N. gonorrhoeae (STI), Chlamydia (STI)
Fungal conjunctivitis: very rare
Candida spp. after topical corticosteroid & antibacterial treatment
Paracoccidioides, Coccidiodes immitis, Blastomyces in immunocompromised
Parasitic conjunctivitis: very rare
Loiasis, Dirofilariasis – parasitic worms
tropical
Chlamydia trachomatis CONJUNCTIVITIS
three types
different serovars type for a different type
- 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 - 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
Chlamydia’s Infectious Cycle and its forms
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
DIAGNOSTIC TESTS FOR CHLAMYDIA
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
GONOCOCCAL CONJUNCTIVITIS
-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
Retinitis
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
Keratitis
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.
ACANTHAMOEBA and what to test with
-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
Blepharitis:
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
Stye:
infection of small glands near base of eyelashes.
Most often caused by S. aureus.
SPECMENS FOR EYE INFECTIONS
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)
EYE SPECIMEN PROCESSING
Direct Specimen Stains
Gram
Giemsa
ELISA/Fluorescence
EYE SPECIMEN PROCESSING
Culture:
what do we get at michener
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
PATHOGENS IN EYE SPECIMENS
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
SUSCEPTIBILITY TESTING/REPORTING FOR EYE SPECIMENS
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.
NON PATHOGENIC FLORA IN EYE SPECIMENS
non sterile (OE) vs sterile samples (OM)
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
ADDED PROCEDURE FOR EYE SPECIMENS GC INVESTIGATION
-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.
OUTER EAR INFECTION
OTITIS EXTERNA (OE)
cause and symp
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
NECROTIZING or MALIGNANT OE
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.
Candida auris
germ tube?
type of pathogen
issue?
risk factor
-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
PROBLEMS WITH C. auris IDENTIFICATION
-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
ASPERGILLUS OTOMYCOSIS
-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
MIDDLE EAR INFECTION
OTITIS MEDIA (OM)
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
SPECIMEN FOR OM
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
ORGANISMS CONSIDERED PATHOGENS IN OM
OE SPECIMEN PROCESSING
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
PATHOGENS IN OE CULTURE
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
SUSCEPTIBILITY TESTING FOR OE
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.
OM SPECIMEN PROCESSING
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
WORK UP OF TYMPANOCENTESIS CULTURE
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.
