EYE & EAR CULTURES

1. EYE & EAR CULTURES

2. ANATOMY OF THE EAR Tympanic membrane Inner ear Eustachian tube Middle ear

3. 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

4. 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

5. OTITIS MEDIA: TYMPANIC MEMBRANE Bulging tympanic membrane

6. 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)

7. 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

8. OTITIS EXTERNA Infection and irritation in the outer ear

9. 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

10. OBTAINING A SPECIMEN FOR CULTURING THE OUTER EAR

11. 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

12. EYE ANATOMY

13. 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)

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

15. 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

16. CONJUNCTIVITIS (“pink eye”) • Causative agents • Adults • Staphylococcus aureus (warmer climes) • Streptococcus pneumoniae (cooler climes) • Infants & children • Haemophilus influenzae • Staph. aureus • Streptococcus spp. • Enterobacteriaceae

17. CONJUNCTIVITIS OR“PINK EYE”

18. 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

19. 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)

20. CONJUNCTIVITIS

21. 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

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

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

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

25. 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

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

27. 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

28. 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

29. Congenital cataracts • Result of mother with rubella

30. 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

31. 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

32. ENDOPHTHALMITIS

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