EYE & EAR CULTURES

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

EAR INFECTIONS & CULTURES F Otitis media –Most common infection in young children –1/3 rd 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 F Specimen collection by typanocentesis F 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 F 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 F Maceration of outer ear from swimming, hot and humid weather, or hot tub use F Pools with high coliform counts increase risks F Symptoms –Irritation and itch –Swelling and pain

OTITIS EXTERNA Infection and irritation in the outer ear

OTITIS EXTERNA F Specimen collection - insertion of sterile swab into ear F Causative agents –Pseudomonas spp. (most common) –Enterobacteriaceae spp., including E. coli and Proteus spp. F Prevent through complete drying of ears using acidic alcohol (vodka and vinegar?) F Rx with antibiotic containing otic drops

OBTAINING A SPECIMEN FOR CULTURING THE OUTER EAR

EAR CULTURES F Set-ups: –CAP (H. influenzae) “chocolate Agar plates” –BAP ( Blood Agar Plates) –MacC or EMB –CNA? u 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 F 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 F Truly invasive organisms –N. gonorrhoeae and meningitidis –Streptococcus pneumoniae –Listeria monocytogenes –Corynebacterium diptheriae –Staphylococcus aureus –Pseudomonas aeruginosa

EYE INFECTIONS F Normal flora –*Coagulase negative staphylococci –*Propionibacterium spp. –Corynebacterium spp. –Staphylococcus aureus –Haemophilus influenzae –Streptococci pneumoniae F NF usually protects eye from invasion by more harmful organisms

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

CONJUNCTIVITIS OR “PINK EYE”

CONJUNCTIVITIS F Causative agents –Neonates u Neisseria gonorrhoeae (large volume of exudate) u Neisseria meningitidis (large volume of exudate) u Chlamydia trachomatis (requires special culturing or diagnostic techniques) –Viruses, fungi, and parasites –Allergies

CONJUNCTIVITIS F 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 AGENTEXUDATE & CELLS LIDS SWELL NODES INVOLVED ITCH BacteriaPus,PMNs, clear ModerateNo VirusesMonos, clear MinimalYesNo AllergyEos., clear Moderate to severe NoIntense

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

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

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

KERATITIS –Frequently isolated gram negatives u Serratia marcescens - common H 2 O microbe u Proteus mirabilis u Haemophilus influenzae u Moraxella spp. –Frequently isolated gram positives u Streptococcus pneumoniae u Viridans streptococci u Coagulase negative staphylococci –Mycobacterium other than tb. (MOTT) –Viruses, fungi, parasite

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

KERATITIS F Specimen collection –same as conjunctivitis F Set-ups: –CAP –BAP –Thioglycollate broth –Anaerobic BAP? –All purpose fungal medium? –Smear F Special techniques required for Chlamydia, viruses, parasites

KERATITIS F 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 F Result of mother with rubella

Endophthalmitis F Endophthalmitis is an inflammation of the internal coats of the eye. F It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. F Other causes include penetrating trauma and retained intraocular foreign bodies

ENDOPHTHALMITIS F Nosocomial sequellae of eye surgery F Sight threatening F Samples are aspirates of anterior chamber or vitreous humor fluids F Common isolates –Coagulase negative staphylococci –Viridans streptococci –Enterococci –Gram negative bacilli –Other organisms associated with conjunctivitis & keratitis

ENDOPHTHALMITIS

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