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