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EYE & EAR CULTURES. ANATOMY OF THE EAR. Tympanic membrane. Inner ear. Eustachian tube. Middle ear. EAR INFECTIONS & CULTURES. Otitis media Most common infection in young children 1/3 rd of all pediatric visits due to infection of middle ear - PowerPoint PPT Presentation
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EYE & EAR CULTURES
ANATOMY OF THE EAR
Tympanic membrane
Middle ear Eustachian tube
Inner ear
EAR INFECTIONS & CULTURES
Otitis media– Most common infection in young children– 1/3rd of all pediatric visits due to infection of
middle ear– Often the result of viral or bacterial infections
of the respiratory tract– Clearance mechanism of Eustachian tubes
impaired; tubes shorter in children than adults– Cultures required only infrequently
OTITIS MEDIA
Specimen collection by typanocentesis Symptoms
– Fever and irritability (may be only symptom)– Tugging at affected ear– Ear pain and red, bulging tympanic membrane– Drainage of purulent secretions into ear canal
OTITIS MEDIA: TYMPANIC MEMBRANE
Bulging tympanic membrane
OTITIS MEDIA
Causative agents– *Streptococcus pneumoniae– *Haemophilus influenzae– Streptococcus pyogenes– Moraxella catarrhalis (in children)– Staphylococcus aureus– Gram negative bacilli (following antibiotics)– Group B beta streptococci (newborns)
SWIMMERS EAR – OTITIS EXTERNA
Maceration of outer ear from swimming, hot and humid weather, or hot tub use
Pools with high coliform counts increase risks Symptoms
– Irritation and itch– Swelling and pain
OTITIS EXTERNA
Infection and irritation in the outer ear
OTITIS EXTERNA
Specimen collection - insertion of sterile swab into ear
Causative agents– Pseudomonas spp. (most common)– Enterobacteriaceae spp., including E. coli and
Proteus spp. Prevent through complete drying of ears using
acidic alcohol (vodka and vinegar?) Rx with antibiotic containing otic drops
OBTAINING A SPECIMEN FOR CULTURING THE OUTER EAR
EAR CULTURES Set-ups:
– CAP (H. influenzae) “chocolate Agar plates”– BAP ( Blood Agar Plates)– MacC or EMB– CNA?
nalidixic acid and colistin in Columbia Blood Agar– the growth of most gram-negative bacteria, including
Klebsiella, Proteus and Pseudomonas species
– Thioglycollate broth (middle ear sources only)– Smear
EYE ANATOMY
EYE INFECTIONS & CULTURES
Conjunctiva and cornea invaded by few organisms if barrier is intact– Lysozyme (gram positives)– Immunoglobulins– “Filters” (lashes)– Other anatomic features (density of tissues)
EYE PATHOGENS
Truly invasive organisms– N. gonorrhoeae and meningitidis– Streptococcus pneumoniae– Listeria monocytogenes– Corynebacterium diptheriae– Staphylococcus aureus– Pseudomonas aeruginosa
EYE INFECTIONS
Normal flora– *Coagulase negative staphylococci– *Propionibacterium spp.– Corynebacterium spp.– Staphylococcus aureus– Haemophilus influenzae– Streptococci pneumoniae
NF usually protects eye from invasion by more harmful organisms
CONJUNCTIVITIS (“pink eye”)
Causative agents– Adults
Staphylococcus aureus (warmer climes) Streptococcus pneumoniae (cooler climes)
– Infants & children Haemophilus influenzae Staph. aureus Streptococcus spp. Enterobacteriaceae
CONJUNCTIVITIS OR“PINK EYE”
CONJUNCTIVITIS
Causative agents– Neonates
Neisseria gonorrhoeae (large volume of exudate)
Neisseria meningitidis (large volume of exudate)
Chlamydia trachomatis (requires special culturing or diagnostic techniques)
– Viruses, fungi, and parasites– Allergies
CONJUNCTIVITIS
Common means of infection– Birth canal (eg., Chlamydia trachomatis &
Neisseria gonorrhoeae)– Hand-eye contact (N. gonorrhoeae, Staph.
aureus, H. influenzae)– Contaminated cosmetics and medications
(Staph. aureus, gram negative bacilli)
CONJUNCTIVITIS
AGENT EXUDATE& CELLS
LIDSSWELL
NODES INVOLVED
ITCH
Bacteria Pus,PMNs,clear
Moderate No No
Viruses Monos,clear
Minimal Yes No
Allergy Eos., clear
Moderate to severe
No Intense
CONJUCTIVITIS Specimen collection
– Dacron (not cotton) swabs (cotton has oils with antimicrobial properties)
– Conjunctival scrapings or expressed fluids– Often collected by opthalmologist– When possible, inoculate directly onto media
CONJUNCTIVITIS
Set-ups– CAP (H. influenzae and N. gonorrhoeae)– BAP – Smear
Special techniques required for Chlamydia trachomatis, viruses, parasites
KERATITIS Ocular emergency Causative agents
– Extremely critical cases due to rapidly acting (24/48 hrs) enzyme-mediated “corneal melt”
Pseudomonas aeruginosa Staphylococcus aureus
KERATITIS
Keratitis is a condition in which the eye's cornea is inflamed.
KERATITIS– Frequently isolated gram negatives
Serratia marcescens - common H2O microbe Proteus mirabilis Haemophilus influenzae Moraxella spp.
– Frequently isolated gram positives Streptococcus pneumoniae Viridans streptococci Coagulase negative staphylococci
– Mycobacterium other than tb. (MOTT)– Viruses, fungi, parasite
KERATITIS
Common vectors– Contact lenses!!!– Latent viruses– Contaminated soil and water– Damage out doors from trees and sand
KERATITIS Specimen collection –same as conjunctivitis Set-ups:
– CAP– BAP– Thioglycollate broth– Anaerobic BAP?– All purpose fungal medium?– Smear
Special techniques required for Chlamydia, viruses, parasites
KERATITIS
Limulus lysate test may be rapidly diagnostic for infections with g- bacilli– Hemolymph from horseshoe crab plus microbe
(LPS?) Clot– Only useful for detection of gram negatives– Does not differentiate between gram negatives
Congenital cataracts Result of mother with rubella
Endophthalmitis
Endophthalmitis is an inflammation of the internal coats of the eye.
It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself.
Other causes include penetrating trauma and retained intraocular foreign bodies
ENDOPHTHALMITIS Nosocomial sequellae of eye surgery Sight threatening Samples are aspirates of anterior chamber or
vitreous humor fluids Common isolates
– Coagulase negative staphylococci– Viridans streptococci– Enterococci– Gram negative bacilli– Other organisms associated with conjunctivitis
& keratitis
ENDOPHTHALMITIS
ENDOPHTHALMITIS
Set-ups:– CAP– BAP– Anaerobic BAP– All purpose fungal medium– Broth medium– Smear– Extra samples held for viral and chlamydial
work-ups