Viral Conjunctivitis and Trachoma Quiz

Eye Infections

• Normal Eye Microbiota: Staph. epidermidis, Lactobacillus spp., and P. acnes
• Eye Defense Mechanisms: Eyelashes, blinking (15-20 times/minute), secretions from lacrimal glands and goblet cells washing away bacteria and foreign matter, lysozyme and IgA in tears
• Lid Infections (Etiology: Staph. aureus):
  • Types: Lid margin infection (blephritis), Lid gland & follicle infection (sty)
  • Clinical Presentation: Irritation, redness, burning, itching
• Conjunctivitis (Etiology):
  • Bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella species, N. gonorrhoeae, and C. trachomatis
  • Viral: HSV-1, Adenovirus, Enterovirus, Coxsackie virus A24, systemic viruses like measles, mumps, rubella, chickenpox, COVID-19
  • Transmission: Direct and indirect contact, auto-inoculation from genital infections.
• Types of Conjunctivitis: HSV, Pharyngo-conjunctival fever (PCF), trachoma, ophthalmia neonatorum

Keratitis

• Etiology:
  • Bacterial: Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa
  • Viral: HSV-1, Adenovirus, Varicella Zoster Virus (VZV)
  • Fungal: Fusarium solani
• Clinical Presentation: Corneal irritation, pain, lacrimation, photophobia, gritty feeling, dendritic branching ulcer (in HSV), vesicles (in VZV)

Herpes Simplex Virus (HSV)-1 Keratitis

• Structure: Enveloped ds DNA virus
• Pathogenesis: Latent infection in trigeminal ganglia reactivates in immunosuppressed hosts, causing dendritic branching ulcer, repeated infections leading to scarring and blindness
• Treatment: Topical and oral acyclovir

Epidemic Keratoconjunctivitis (EKC), "Adenovirus 8 & 19"

• Structure: Non-enveloped ds DNA Viruses, type 8 and 19 adenoviruses causing EKC which is among the most serious adenoviral eye infections
• Mode of Transmission: Close personal contact, use of non-sterile ophthalmic instruments

Herpes Zoster Ophthalmicus ("VZV")

• Pathogenesis: Latent infection in trigeminal ganglia, reactivates in immunosuppressed hosts, causes unilateral painful vesicles and keratitis, conjunctivitis, and iritis
• Treatment: Oral acyclovir only

General Characteristics of Important Bacterial Agents

• Staphylococcus aureus: Gram-positive cocci, coagulase-positive, beta-hemolytic on blood agar, mannitol fermenter, golden yellow colonies
• Streptococcus pneumoniae: Gram-positive cocci, catalase-negative, alpha-hemolytic on blood agar, optochin & bile sensitive
• Haemophilus influenzae: Small gram-negative coccobacilli, requiring factors X and V for growth on laboratory media
• Neisseria gonorrhoeae: Gram-negative diplococci, oxidase-positive
• Pseudomonas aeruginosa: Gram-negative bacilli, aerobic, oxidase-postive, produces blue-green pigment (pyocyanin and pyoverdine) on nutrient agar

Infections of the Deeper Layers of the Eyes

• Causes: Traumatic injury, blood-borne infections (opportunistic, in utero infections, CMV causes chorioretinitis in AIDS patients, ocular complications of West Nile virus)
• Diagnosis: Conjunctival swab or corneal scrapings, blood and chocolate agar plates (incubated under 5% to 10% CO2), Gram stained films, biochemical tests, and PCR for viral infections.

Otitis Externa (External Ear Infections)

• Causes: Pustule or furuncle (typically Staphylococcus aureus), acute diffuse (often swimmers ear, with Pseudomonas aeruginosa and other gram-negatives), malignant (necrosis with Pseudomonas aeruginosa and anaerobes).
• Clinical Presentation: Often seen in patients with diabetes (malignant progression)
• Pathogenesis: Damage and maceration (softening of tissues) is key in the acute diffuse form.
• Diagnosis: Primarily clinical; culture of discharge, aspirate of middle ear fluid if possible.
• Treatment: Antimicrobials (follow-up crucial due to risk of chronic otitis)

Test your knowledge on viral causes of conjunctivitis and the infections related to trachomatis. This quiz covers various aspects, including transmission, immunotypes, and prevalence of trachoma. Answer the questions to enhance your understanding of these ocular infections.