Microbiology of Eye & Ear Flashcards
Inflammatory disease of the eyelid margin where too much oil is produced . Often associated with conjunctivitis.
Belpharitis (usually caused by staphylococcus aureus)
Infection of the conjunctiva
Conjunctivitis
Infection of the cornea. Vision defects, photophobia, pain, foreign body sensation.
Keratitis.
- viral cause HSV-1, adenovirus, VZV
- bacterial keratitis (staph aurus and epidermidis, pseudomonas aeroginosa, bacillus cereus)
- fungal infection in warm, humid environment (acanthamoeba - contact lens cleaning fluids)
*treat bacteria moxifloxacin eye drops, HSV-1 trifluidine +acyclovir
Infection of the conjunctiva and cornea
Keratoconjunctivitis (HSV-1). If corneal involvement treat with topical trifluridine and systemic acyclovir.
Infection of the iris, ciliary body, and choroid.
Uveitis..caused by Treponema palladium, HSV, VZV
Usually linked to system disease (CMV and AIDS). Infection of choroid and retinal layers. Blurred vision and visual field defects. Floaters, no pain. Blood borne route via retinal arteries.
Chorioretinitis (posterior uveitis). Toxocara canis and onchocerca volvulus (river blindness via sand flies) parasitic worm infections.
Infection of aqueous and vitreous humor. Recent intraocular surgery esp. cataract with agent coming from normal flora. (pseudomonas, staphylococci, or candida).
Endophthalmitis. Fluorquinolone or vanco injected into eye.
What are the eye’s defense mechanisms?
- Tears contain lysozyme & secretory IgA
- Cornea and sclera provide physical barrier
- Conjunctiva has lymphocytes, plasma cells, neutrophils, and mast cells which produce antibodies and cytokines
- Blinking inhibits microbial attachment
What are the causes of conjunctivitis?
- Viral (most common adult is adenovirus; neonate is HSV-1)
- Bacterial (streptococcus pneumonia, haemophilus influenzae [non-typeable/no envelope), & moraxella catarrhalis)
- Allergic (allergic rhinoconjunctivitis aka hay fever)
- Non-enveloped double stranded DNA virus
- Lytic in epithelial cells and latent in lymphoid
- Highly contagious spread through fomites like swimming pools and towels
Adenovirus
What are the main bugs responsible for acute bacterial conjunctivitis in children?
- Staphlyococcus aureus (Gram + cocci, clusters)
- Streptococcus pneumoniae (Gram + diplococci)
- Haemophilus influenzae (Gram neg coccobacillus)
- Moraxella catarrhalis (aerobic gram neg diplococci)
What are the main bugs responsible for acute bacterial conjunctivitis in adults?
- Staphlyococcus aureus (gram + cocci, clusters)
- Streptococcus pneumoniae (gram + diplococci)
- Escherichia coli (Gram neg rod)
- Pseduomonas aeruginosa (aerobic gram neg rod)
- Moraxella catarrhalis (aerobic gram neg diplococci)
What is the suggested treatment for acute bacterial conjunctivitis (mucopurulent)?
Moxifloxacin (best coverage, expensive, >3 yo) or trimethoprim-polymyxin B
Gram negative intracellular diplococci
Neisseria gonorrhoea (responsible for hyper acute bacterial conjunctivitis) *Promptly treat with ceftriaxone, augmented with topical antibiotics and irrigation
What is conjunctivitis or keratoconjunctivitis that occurs within the first four weeks after birth called?
Opthalmia neonatorum (N. gonorrhoeae, C. trachomatis (serotypes D-K is the STD), Staphylococcus, Streptococcus, E. coli, H. influenzae or H. simplex)
*Treat with prophylactic erythromycin ointment on eyes right after birth
What bacteria is associated with the leading cause of worldwide blindness due to multiple infections (no long lasting immunity)? Associated with chronic conjunctivitis.
Chlamydia trachomatis serotypes A-C. Serotypes D-K is associated with inclusion conjunctivitis (usually found in U.S.). Coinfection with N. Gonorrhea should be considered. Treat with systemic azithromycin and improve hygiene. Treat sexual partner. Elementary body (hardy) enters epithelial cells, converts to reticulate body, replicates via binary fission.
External localized inflammation often on lower lid due to bacterial growth in eyelash follicle, if forms inside or under eyelid called hordeolum. Erythromycin ointment.
Stye
Lipogranulomas-small lump plugging of the meibomian gland.
Chalazion
Pyrimidine analog effective against acyclovir resistant virus cuz it can be phosphorylated by host kinases (acyclovir only by viral thymidine kinase). Only use topically!
Trifluridine
- Gram negative, aerobic rod, flagella
- Forms blue green pigment (pyocyanin)
- Free living in water and soil, hardy
- contact lens wearers at greater risk
- Opportunistic
- forms biofilms
Pseudomonas aeruginosa
What are the common etiologic agents of acute otitis media?
-Streptococcus pneumoniae (Gram + diplococci): 25-50%
-Haemophilus influenzae (Gram neg coccobacillus; mostly non-typable aka no capsule; unlike strain for meningitis): 15-30%
-Moraxella catarrhalis (aerobic gram neg diplococci): 3-20%
-Viral (especially RSV, rhinovirus): 5-22%
-No pathogen identified: 16-25%
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- Gram positive diplococcus
- Transmitted thru secretion contact
- Asymptomatic colonization of naso-oropharynx
- 91 serotypes (23 covered by vaccine, most likely ones to cause meningitis)
- Chronic diseases interfere with normal defense can increase susceptibility
Streptococcus pneumoniae
- Resistance due to changes in penicillin binding protein
- Capsule (blocks phagocytosis)
- Choline binding proteins (bind carbs present on surface of epithelial cells)
- Neuraminidases - cleave sialic acid in host mucins
- Autolysin A (degrades peptidoglycan causes alpha hemolysis
- Pneumolysin (pore forming toxin disrupts cilia)
- Gram negative coccobacillus
- Non-motile
- Biofilms
- Facultative anaerobe
- Humans only known host
Haemophilus Influenza
- resistance due to beta lactamases
- non typable (no capsule) for otitis media, capsule is in meningitis causing strains
- Gram negative diplococcus
- aerobic
- oxidase positive
- Colonization of upper respiratory tract in infants
- Hockey puck test
Moraxella catarrhalis
-resistance due to beta lactamases
