Microbiology and Pharmacology Flashcards
(35 cards)
What are the bacterial causes of conjunctivitis in neonates?
- S.aureus, N.gonorrhoeae, C.trachomatis
- must be treated by ophthalmology
What are the bacterial causes of conjunctivitis in normal age groups?
S.aureus or S.pneumoniae with H.influenzae in children
How is bacterial conjunctivitis diagnosed and treated?
- Swab
- Give chloramphenicol drops (keep in fridge) or ointment (can’t see after administration)
- Gentamicin for pseudomonas
What are the viral causes of conjunctivitis?
this isn’t as bad as bacterial as there is no sticky discharge
- adenovirus
- herpes simplex (skin rash)
- herpes zoster (in a ganglion)
What is the treatment for viral conjunctivitis?
aciclovir (also stops post-herpetic neuralgia)
What are the features of chlamydial conjunctivitis?
- chronic
- unresponsive to treatments
- low grade red eye with follicles (like grains of rice) on the conjunctiva
- becomes scarred if it is not treated
- use topical oxytetracycline
What are the features of bacterial keratitis in the cornea?
- Pus in the eye called hypopyon
- risk of scarring or the bacteria can cause perforation
- hourly drops
- usually due to scar or contact lenses but is rare
- scrape for diagnosis
- give quinolone eg ofloxacin or gentamicin and cefuroxime
What are the causes of viral keratitis in the cornea?
Herpes
- Causes dendritic ulcer
- Fluorescent dye to show where the epithelium is missing
- painful and recurrent
- Never give steroid eye drops as the virus can cause cornea to melt and perforation of cornea!!!!!
Adenovirus
- Blurred vision for several months
- Follows an URTI and is contagious
What are the features of fungal and other causes of keratitis?
- Acanthamoeba is extremely painful and is due to contact lens, culture the contact lenses
- Fungal is seen in farmers, is more defined, multiple organisms, treat with topical antifungals
What are the features of endophthalmitis of the eye globe?
- post-surgical
- loss of sight within 48 hours
- very painful and the patient will be really unwell
- S. epidermidis
- treat with injected antibiotics into the vitreous under LA with a broad gauge needle
What are the features of cellulitis?
- Orbital cellulitis pushes the eye forward by a bag of pus
- Associated with ethmoid sinuses
- unwell and pyrexial
- erythema will be perfectly demarcated
- children
- can be preseptal or orbital
- is staph, strep, coliforms, H. influenzae or anaerobes
What are the causes of chorioretinitis?
- caused by AIDS
- herpes in immunosuppressed patients
- Toxoplasma is a protozoa infection which can be latent and reactivate
- Toxocara canis is worm
What are the features of chloramphenicol?
- Topical antibiotic
- Stops bacterial protein being made
- Bactericidal for strep and haemophilus
- Bacteriostatic for staph
What main eye antibiotic classes inhibit cell wall synthesis?
- Penicillins
- Cephalosporins
with their B lactam ring
What main eye antibiotic class inhibits nucleic acid synthesis?
- Quinolones eg ofloxacin
inhibits DNA gyrase so nucleic acid synthesis so there is cell death
What are the main antiviral agents used?
- acyclovir and ganciclovir
- inhibits viral DNA synthesis
What is the benefit of chloramphenicol as a drug?
it is both lipophilic and hydrophilic so can penetrate all layers of the cornea
What are hydrophobic and hydrophilic drugs limited by?
- hydrophilic drugs are limited by the epithelium
- hydrophobic drugs are limited by the stroma
How can topical steroids be altered to allow them to be better suited for their purpose?
- add acetate = become hydrophobic
- add phosphate = become hydrophilic
What is benzalkonium chloride used for?
- kill bacteria
- preservative
- depletes the tear film = aids penetration of some drugs
What are the features of prednisolone acetate?
- hydrophobic
- good for uninflamed cornea
- used in post-op
What are the features of prednisolone phosphate?
- hydrophilic
- not good for uninflamed cornea
- used for cornea disease for low doses of steroids
How can the systemic effect of drugs be stopped?
close off drainage system for 5 minutes then wipe excess tears to stop leaking down the throat
What are steroids used for?
- post op cataracts
- uveitis
- prevent corneal graft rejection
- temporal arteritis
