Microbiology of the Eye 3

what is Keratitis

Inflammation of the cornea

keratitis is Most common infection for?

CL wearers

Symptoms for keratitis

– Eye redness, pain

– Excessive tears or discharge

– Difficulty opening eye and blurred vision

– Feeling of graininess in the eye

–Photophobia

–Can lead to blindness

name shaded areas

keratitis is Typically ______?

viral, although bacteria, fungi and parasites can also cause the infection

name the viruses for keratitis

• Herpes Simplex Virus Type 1 (a)

• Varicella Zoster (Chickenpox Virus)

• Adenovirus (Common Cold)

name Bacteria (90%) for keratitis

• Staphylococcus species

• Streptococcus species

• Pseudomonas aeruginosa (b)

name Amoeba for keratitis

• Acathamoeba (c)

name Fungi for keratitis

• Candida albicans, Fusarium

what is the leading cause for keratitis

contact lens wear

name 6 causes for keratitis

-contact lens wear

-Trauma

-Keratopathy

-Immunosuppression plus

-Use of topical corticosteroids

-Swimming

describe how trauma can cause keratitis

Scratches and abrasions to the cornea

describe how Keratopathy causes keratitis

associated with dryness / inflammation of ocular surface

where does Herpes Simplex Virus 1 replicate

Replicates at the skin or mucosal surface

how is Herpes Simplex Virus 1 transmitted

saliva

describe Herpes Simplex Virus 1

• Enveloped

• ds DNA virus

• Icosahedral symmetry

what does Herpes Simplex Virus 1 display

latency, Reactivated by sunlight, trauma, hormones, fever, immunodeficiency

what is Leading cause of viral keratitis

Herpes Simplex Virus 1

what is viral keratitis

Chronic viral infection or recurrent viral infection of the cornea

who doe HSV2 occur in

children during birth

what are the Complications that Herpes Simplex Virus lead to

– Chronic corneal Inflammation

– Corneal ulcers

– Temp or Permanent reduction in vision

– Blindness

name topical treatment for Viral Keratitis Treatment

Acyclovir 3% ointment 5x daily

Ganciclovir 0.15% Virgan Ophthalmic gel 5x daily

Trifluridine 1% Viroptic 9x daily drops max/24hr

in severe infections of keratitis, what would be prescribed

Antiviral Tablets

______ _______ may be used in combination with Antivirals

Steroid Eyedrops

what is bacterial keratitis

serious bacterial infection of the cornea

what is Endophthalmitis

inflammation of interior of the eye

P. aeruginosa Resistance is resistant to?

disinfectants

what is Alginate role for P. aeruginosa Virulence Factors

role in biofilm formation and attachment to surfaces

what is Exoenzyme S role for P. aeruginosa Virulence Factors

Inhibits immune system by Stopping phagocytosis

what is Proteases role for P. aeruginosa Virulence Factors

role in corneal ulceration

what does P. aeruginosa and alginate do

Can be highly mucoid (alginate)

– Forms biofilm

– Acts as an adhesin

– Covers

• Contact lens surface

• Lens case

– Act as a physical barrier to

• Contact lens solution

• Immune system

• Antimicrobials

name 2 P. aeruginosa as a pathogen

Otitis externa

Folliculitis

name the infections of the eye for P. aeruginosa as a pathogen

• Bacterial keratitis

• Contact lens-related infection

how does P. aeruginosa occur with CL’s

Failure to disinfect lenses

Wearing lenses for longer than recommended

Swimming with contact lenses in situ

describe Protozoa

• Classified within the Eukaryota now

• Highly diverse group of organisms

what is the only common feature of protozoa

• Simple eukaryotic organism

• Single cell

name 3 Common pathogenic that protozoa cause

• Malaria

• Trichomoniasis (a)

• Giardiasis (b)

describe the cell structure for amoeba

Protoplasm enclosed by a membrane

where is Acanthamoeba found

lakes, in the environment

what is Amoebic Keratitis (AK)

rare parasitic eye infection from a certain type of amoeba

what causes Amoebic keratitis

Soil/Dirty water

Symptoms of Amoebic keratitis

• Severe pain

• Photophobia

• Tearing

• corneal lesions

how can keratitis be diagnosed

symptoms, Amoebae=Visualised by confocal microscopy, Growth of bacteria or amoebae from corneal scrapings of the eye

name the 3 types of treatments for keratitis

bacteria, viral, Acanthamoebic

when would bacterial medication be used for keratitis

Mild bacterial keratitis, antibacterial eye drops

when would viral medication be used for keratitis

– Antiviral eye drops and oral antiviral medications

– Viral keratitis may recur

what can be used to inhibit immune response and promote acathamoebic growth

Steroids

how is Fungal Keratitis diagnosed

Deep Corneal Scrapings or Biopsy, PCR test, Fungal Culture