Microbiology-Eye, Ear & Sinus Infections Flashcards
What is it called when the structures indicated below become infected?
1) Blepharitis = eyelid 2) Keratitis = cornea 3) Uveitis = iris, choroid or ciliary body 4) Retinitis = retina 5) Conjunctiva = conjunctivitis 6) Endophthalmitis = vitreous or aqueous humor
Who is the most common cause of this?
Most common infectious cause of blepharitis is staph aureus.
This patient came to see you because his right eye was stuck shut when he woke up this morning. Is the cause of this patient’s red eyes viral or bacterial?
The most common form of conjunctivitis is viral, caused by adenovirus. Other common viral causes are HSV, measles and varicella. Common bacterial causes are staph aureus, strep pneumo, H. influenzae and moraxella.
How is bacterial conjunctivitis different from viral conjunctivitis?
1) Bacterial unilateral, Viral bilateral 2) Bacterial purulent discharge that keeps appearing when you wipe the eyelid, Viral watery discharge that is gone after the morning 3) Bacterial conjunctival edema, Viral little edema 4) Preauricular nodes more common virally.
What characterized allergic conjunctivitis?
Bilateral, watery, edema and ITCHING.
A 44 year old patient presents with photophobia, blurred vision and a foreign body sensation in his right eye. Slit lamp exam reveals opacification of the cornea. What are common causes of this?
Bacteria (staph aureus, pseudomonas, cornyebacteria, chlamydia), Viral (HSV, adenovirus), Fungi (fusarium), Protozoa (acanthamoebae) and Helminths (onchocera volvulus).
What do you do if you see a patient with keratitis?
Immediate referral to an ophthalmologist.
A mother gives birth to a child. Shortly thereafter the child has keratitis. How might the mother have transferred an organism that would cause keratitis in her newborn?
Chlamydia, gonorrhoeae and HSV. This is the only way genital chlamydia can cause keratitis.
What is the world’s leading infectious cause of blindness?
Chlamydia trachomatis. Outside of the US, different serotypes first cause a terrible conjunctivitis that infects the eyelid, then it scars and causes the upper/lower eyelids to turn in on the eye and cause traumatic keratitis by eyelashes scratching the eye.
A patient presents with difficulty seeing and red eyes. Physical exam reveals a hazy retina and hypopyon (WBCs in anterior chamber). How did this patient get this condition?
This is endophthalmitis. This can be caused by trauma (cataract surgery) or hematogenous spread. Common offenders in trauma are B. cereus, staph, strep, klebsiella, pseudomonas & candida. Common offenders in hematogenous spread are b. cereus (drug users), staph, strep, gram negative rods and candida.
What is the most common way to get eye infection?
Trauma. Hemotogenous spread is also common.
Gram positive rod that causes chronic endophthalmitis.
Propionibacterium acnes
Common causes of congenital chorioretinitis
Toxoplasmosis & CMV
Common causes of adult chorioretinits when immunocompromised.
Tb, toxoplasmosis, candida, aspergillus, histoplasmosis, fusarium, HSV, VZV, CMV
Why do ID docs not recommend using Q-tips?
Cerumen is acidic (inhibits bacterial growth), hydrophobic (repels water) and sticky (traps debris)
Why are swimmers at risk for otitis externa?
They swim so much that the tissue does not have time to dry out and it becomes macerated.
A patient comes to see you with ear pain. Physical exam reveals pain when pulling on the earlobe and inability to view the tympanic membrane because it was too painful for the patient. What organisms cause this?
This patient has otitis externa. Bacterial: pseudomonas, staph aureus. Fungal: candida, aspergillus.
Why can you tell you kid to pick their nose instead of blowing their nose?
When you blow your nose you can push commensal bacteria back into the sinuses and cause sinusitis.
What are typical offenders in chronic sinusitis?
Bacteria and fungus (aspergillus, mucor and dematiaceous molds). Note how the aspergillus is breaking through the bone of the left maxillary sinus below.
Why are strep pneumoniae and H. influenzae leading causes of bacterial conjunctivitis, otitis media and sinusitis?
They both have a polysaccharide capsule and can only be attacked by complement and antibody.
What people are at increased risk for bacterial conjunctivitis, otitis media and sinusitis?
People with antibody or complement deficiencies (common variable immune deficiency, splenectomy). These people are at risk for serious infections by encapsulated bacteria (S. pneumo, H. influenzae, Neisseria) because they cannot opsinize the capsule.
