EYE & EAR CULTURES ANATOMY OF THE EAR Tympanic membrane Inner ear Middle ear Eustachian tube 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 LIDS SWELL NODES INVOLVED Bacteria Pus,PMNs, clear Viruses Monos, clear Allergy Eos., clear Moderate No No Minimal No Yes Moderate No to severe ITCH 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