essential microorganisms and infectious diseases in ocular structures

streptococcus pneumoniae

gram positive lancet shaped diplococci

virulence: polysaccharide capsule, pneumolysin

infections: bacterial conjunctivitis, keratitis

clues: painful central ulcer, hypopyon

haemophilus influenzae

gram negative coccobacillus

virulence: IgA protease, mucosal adherence

infections: purulent conjunctivitis

clues: thick purulent discharge, common in children 

adenovirus

family: adenoviridae, dsDNA, nonenveloped

infections: viral conjunctivitis, keratoconjunctivitis

clues: watery discharge, hymphadenopathy, highly contagious

herpes simplex virus

family: herpesviridae, dsDNA, enveloped

infections: herpetic kertitis, blepharoconjunctivitis

clues: dendritic corneal ulcers on fluorescein

varicella zoster virus

family: herpesviridae, dsDNA

infections: HZO, keratitis, conjunctivitis, uveitis

clues: unilateral rash, hutchinson sign, corneal involvement

acanthamoeba spp. 

free living amoeba 

infections: acanthamoeba keratitis 

clues: severe pain out of proportion, ring infiltrate, linked to contact lenses and contaminated water 

conjunctivitis

etiology: adenovirus, s. aureus, s. [neumoniae, haemophilus influenzae

symptoms: redness, irritation, tearing, purulent or watery discharge

diagnosis: clinical, swab only if severe or recurrent

treatment: viral hygiene / lubrication, bacterial topical antibiotics

prevention: hand hygiene, avoid sharing towels / cosmetics

notes: viral = feeling of sand in eye, bacteria = purulent in mornings

blepharitis

etiology: s. aureus, eyelid margin inflammation

symptoms: red swollen eyelids, crusting at eyelashes

diagnosis: clinical

treatment: warm compresses, eyelid hygiene, topical antibiotics

prevention: daily eyelid cleaning in predisposed individuals

notes: other types of diseases = seborrheic dermatitis or demodex infestation or meibomian obstructed glands

keratitis 

etiology: pseudomonas aeruginosa, s. areus, s/ penumoniae, HSV 1

symptoms: pain, photophobia, corneal opacity / ulcer 

diagnosis: slit lamp exam, corneal scraping 

treatment: intensive topical antibiotics, antivirals for HSV 

prevention: proper contact lens hygeine 

herpes zoster ophathalmicus

etiology: reactivation of VZV in ophthalmic nerve

symptoms: unilateral vescular rash, eye pain, photophobia, hutchinson sign, lesion on nose tip - high corneal risl

diagnosis: clinical, PCR if needed

treatment: systemic antivirals and pain control

prevention: zoster vaccination in older adults

endophthalmitis

etiology: s. epidermis, s. aureus, pseudomonas auruginosa, candida spp

symptoms: sudden pain, redness, vision loss, hypopyon

diagnosis: urgent ophthalmologic exam and vitreous / aqueous sampling

treatment: intravitreal antibiotics and vitrectomy

prevention: strict aseptic technique in oncular procedures