Microbiology Flashcards
Conjunctivitis
Inflammation of the conjunctiva (skin of the eye)
Conjunctivitis features
Red and swollen conjunctiva
Watery or pus-containing discharge
Discomfort
Bacterial Conjunctivitis Aetiology neonates
Staph Aureus
Neisseria Gonorrhoea
Chlamydia Trachomatic
Refer all cases to ophthalmology
Bacterial conjunctivitis aetiology
Staph Aureus
Step Pneumonia
H.influenzae (especially children)
Bacterial conjunctivitis treatment
Swab Topical antibiotic (chloramphenicol)
Avoid chloramphenicol if history of aplastic anaemia or allergy
Viral Conjunctivitis Aetiology
Adenovirus
Herpes Simplex
Herpes Zoster
Viral Conjunctivitis Treatment
Anti-virals for herpes
Topical lubricants for adenovirus
Chlamydial Conjunctivitis
often chronic history and unresponsive to treatments
Suspect in bilateral conjunctivitis in young adults
+/- symptoms of urethritis, vaginitis
need contact tracing
Chlamydial conjunctivitis consequence
Subtarsal scarring
Keratitis
Inflammation of the cornea of the eye
Microbial Keratitis
bacteria
viruses
fungi
acanthamoeba
Bacterial keratitis
Need admission for hourly drops
Daily review
Usually in association with other corneal pathology or contact lens wear
Viral Keratitis Aetiology
herpes
adenovirus
Herpetic keratitis feature
Dendritic Ulcer
- very painful and can be recurrent
Recurrence usually results in reduced corneal sensation
herpetic keratitis Treatment
Topical antiviral (ganciclovir)
NO STEROIDS (can cause corneal melt and perforation of cornea)
Adenoviral Keratitis features
Sub Epithelial infiltrates
Normally bilateral
Usually follows an URTI/ conjunctivitis
May affect vision
Adenoviral Keratitis Treatment
Usually self-limiting
May require steroids to speed up recovery if chronic + vision problems
Fungal keratitis - epidemiology and features
Often chronic history
Work outside or have ocular surface disease
Corneal lesions (more defined than bacterial keratitis )
often diagnosed late
Fungal keratitis treatment
Topical anti-fungals
- natamycin amphotericin
Acanthamoeba keratitis
Contact lenses
Often extremely painful- can be diagnosed late
Culture contact lenses
Orbital Cellulitis Organisms
Staphylococci Streptococci Coliforms H.influenzae Anaerobes
Orbital Cellulitis Features
painful (especially on eye movement)
proptosis (forward displacement of eye- exophthalmos)
Often associated with paranasal sinusitis
Pyrexial
Sight threatening
Orbital Cellulitis Investigation
CT scan
- identify orbital abscesses
Orbital Cellulitis pattern of spread
Direct extension from sinus
Extension from focal orbital infection
Post-operative
Orbital Cellulitis management
Suggestion of restriction of muscles or optic nerve dysfunction
–> scan
Broad spectrum antibiotic and monitor
Endophthalmitis
Inflammation, usually due to infection, within the eye
- Devastating infection
Endophthalmitis Features
Post surgical or endogenous
Very painful and decreasing vision
Very red eye
Sight threatening
Endophthalmitis Organisms
Commensals
- Mainly staph epidermis
Endophthalmitis Treatment
Intravitreal amikacin/ ceflazidime and topical antibiotics
Chorioretinitis
Inflammation involving both the choroid and retina
Very rare 9mainly seen in immunocompromised
Chorioretinitis Organisms
CMV in AIDs HSV/ HZV Endogenous (candida) Toxoplasma Gondii Toxocara canis (worm)
Toxoplasmosis aetiology
Protozoan Infection
Congenital or acquired
- contaminated soil or undercooked meat
Toxoplasmosis features
Mild flu like illness
Immunocompetent patients
- latent phase with cysts forming
Rarely causes a problem
Toxoplasmosis Treatment
Rarely requires treatment
Systemic treatment if cysts become sight threatening
Diagnosis of eye infections
Swabs for culture
- bacterial
- chlamydial
- viral
Aqueous/ nitrous culture in endophthalmitis
Microscopy/ culture for acanthoemeba
Serology for toxoplasma and toxocara
Antibiotics- mechanisms of action (3)
Inhibit protein synthesis
Inhibit cell wall synthesis
inhibit nucleic acid synthesis
Chloramphenicol
Inhibits peptide transferable enzyme
Bacteriocidal
- strep and haemophilis
Bacteriostatic
- staph
Chloramphenicol Side effects
allergy
irreversible aplastic anaemia
grey baby syndrome
bacterial keratitis antibiotics
4-quinolone (Ofloxacin)
- Gram -ve
- NOT active vs strep pneumonia
Gentamicin and Cefuroxime
- Gram +ve and Gram -ve
bacterial conjunctivitis antibiotics
Chloramphenicol
- treats most except pseudomonas aeruginosa
Fusidic acid
- Staph aureus
Gentamicin
- Gram -ve
Antivirals
Ganciclovir
- Inhibits viral DNA synthesis
- base analogue
- Topical and systemic
- tears dendritic ulcers of cornea
Chlamydial Conjunctivitis treatment
Topical oxytracycline
