EYE

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EYE EAR CULTURES
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ANATOMY OF THE EAR
Tympanic membrane
Inner ear
Eustachian tube
Middle ear
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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

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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

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OTITIS MEDIA TYMPANIC MEMBRANE
Bulging tympanic membrane
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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)

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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

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OTITIS EXTERNA
Infection and irritation in the outer ear
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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

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OBTAINING A SPECIMEN FOR CULTURING THE OUTER EAR
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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

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EYE ANATOMY
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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)

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EYE PATHOGENS

• Truly invasive organisms
• N. gonorrhoeae and meningitidis
• Streptococcus pneumoniae
• Listeria monocytogenes
• Corynebacterium diptheriae
• Staphylococcus aureus
• Pseudomonas aeruginosa

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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

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CONJUNCTIVITIS (pink eye)

• Causative agents
• Adults
• Staphylococcus aureus (warmer climes)
• Streptococcus pneumoniae (cooler climes)
• Infants children
• Haemophilus influenzae
• Staph. aureus
• Streptococcus spp.
• Enterobacteriaceae

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CONJUNCTIVITIS ORPINK EYE
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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

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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)

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CONJUNCTIVITIS
AGENT EXUDATE CELLS LIDS SWELL NODES INVOLVED ITCH
Bacteria Pus,PMNs, clear Moderate No No
Viruses Monos, clear Minimal Yes No
Allergy Eos., clear Moderate to severe No Intense
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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

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CONJUNCTIVITIS

• Set-ups
• CAP (H. influenzae and N. gonorrhoeae)
• BAP
• Smear
• Special techniques required for Chlamydia
  trachomatis, viruses, parasites

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KERATITIS

• Ocular emergency
• Causative agents
• Extremely critical cases due to rapidly acting
  (24/48 hrs) enzyme-mediated corneal melt
• Pseudomonas aeruginosa
• Staphylococcus aureus

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KERATITIS

• Keratitis is a condition in which the eye's
  cornea is inflamed.

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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

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KERATITIS

• Common vectors
• Contact lenses!!!
• Latent viruses
• Contaminated soil and water
• Damage out doors from trees and sand

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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

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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

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Congenital cataracts

• Result of mother with rubella

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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

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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

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ENDOPHTHALMITIS
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ENDOPHTHALMITIS

• Set-ups
• CAP
• BAP
• Anaerobic BAP
• All purpose fungal medium
• Broth medium
• Smear
• Extra samples held for viral and chlamydial
  work-ups