Week 1 - G - Microbiology of eye infections Flashcards
Give an example of a gram negative cocci?
Neisseria meningitidis or gonorrhoeae
What is inflammation of the conjunctivae known as? What is inflammation of the cornea known as?
Conjunctivae - conjunctivitis
Cornea - keratitis
What is inflammation of the aqueous and vitreous humour known as?
Endopthalmitis
Bacterial conjunctivits presents with redness of the eye and pus usually What are bacterial causes of conjunctivitis in neonates? (remmeber can get STDs in neonates through mother to infant trasmisission)
Staph aureus
Neisseria gonorrhoeae
Chlamydia trachomatis
In all other ages, bacterial conjunctivits is usually caused by staph aureus or strep pneumonia or ? The third cause is especially common in chidlren
Haemophilus influenza
Child wakes up with eye glued shut The eye is red and itchy and there is a pus like substance leaking What is this?
Bacterial conjunctivits
What is the treatment of bacterial conjunctivits? (not including chlamydia trochamtis)
Bathe / clean the eyelids regularly to remove crusting
Second line - Treat with swab and then chloramphenical eye drops usually 4 times daily
Where should chloramphenical be stored after use? Chloramphenicol should be avoided in patients with allergy What should be suspected if patient complains of worsening symtpoms?
Should be stored in fridge
Worsening symptoms with worsening itchiness may be due to a chloramphenical allergy
What gram negative bacilli does chloramphenical not cover?
Does not cover pseudomonas arguinosa
Viral conjunctivitis usually follows a history of URTI – usually presents with bilateral eye watering What is the most common viral cause of viral conjunctivits?
Viral adenovirus - usually starts in one eye and then spreads but lasts around 2 weeks
What are the symptoms of a viral conjunctivirs?
Presents with a watery discharge and swelling of the conjunctivae
What is another viral cause of viral conjunctivits and can present with a sign on the tip of the nose? What is this sign known as?
Herpes zoster
Sign on tip of nose is the Hutchison sign which means the eye has been affected as the tip of the nose is supplied by the nasociliary nerve which is a branch of the opthalmic nerve
In a patient with herpes zoster - Herpes zoster is infection that results when varicella-zoster virus reactivates from its latent state in a posterior dorsal root ganglion. What should you start the patient on?
Start the patient on oral acyclovir
What can occur long after the shingles disappeared causing a burning pain ?
Post-herpetic neuralgia - there is no cure
What is suspect in bilateral conjunctivitis in young adults ?
CHlamydia trachomatis causing chlamydial conjunctivitis
In adults with chlamydial conjunctivits, where else can they complain of having a pain?
Burning sensation, stinging pain while urinating (observed in both men & women); watery discharge from vagina
What is keratitis?
Inflammation of the cornea of the eye
What is the small transparent canal running through the vitreous gel from the optic nerve to the lens? If infection in the cornea spreads in this it can infect the whole eye
Hyaloid canal - Cloquets canal
Bacterial keratitis can cause the accumulation of inflammatory mediators in the anterior chamber of the eye, appears as a white exudate What is this known as?
Hypopyon
People who wear contact lenses are more likely to get keratitis What bacteria is common in people who wear contact lens as they live in the solution the contact lens is stored in?
Pseudomonas aerguinosa
What is the treatment of the psuedomonas aerguinosa bacteria causing keratitis?
Fluoroquinolone - eg oflaxacin, levoflaxacin
When giving eye drops for bacterial keratitis, an eye scraping is taken and eye drops are then given Which eye drops are given t cover most organism before the scraping culture comes back?
Give flouroqinolone (eg oflaxacin) every one hour for 48 hours
What is a dendritic ulcer the most common sign off? Dendritic meaning branch
Most common sign of herpetic keratitis - herpetic keratitis is due to HSV
Herpetic keratitis is Very painful Can be recurrent recurrences eventually result in reduced corneal sensation What is it treated with? and what should be avoided in treatment?
Treated with topical acyclovir
Avoid treatment with steroids as can cause a corneal melt which can lead to perforation and more infection
Orbital cellulitis can have pain on eye movements What does the orbital septum lie in front? What is orbital cellulitis often associated with?
Orbital septum lies in front of the tarsal plates of the eye
Is associated with paranasal sinusitis
What colour is the eyelid in orbital cellulits? What can happen if left untreated? What is the common bacterial cause of orbital cellulitis in children?
Eyelid is left red/purple
Can cause blindness, compartment syndrome due to swelling
Common cause in children is H.influenza
Orbital cellulitis as said is usually due to Hinfluenza, what other organsims can cause it?
Can be caused by staph aureus and strep pneumoniae
What is a coliform? Give an example?
Gram negative bacilli
Example is Ecoli or klebsiella pneumoniae
Devastating infection inside of the eye Very very painful with decreasing sight Usually due to surgery of the eye eg cataracts What is this known as?
Endopthalmitiis - treat with injection antibiotics into the eye
What commensal is the most common cause of endopthalmitis?
Staph epidermis
What is the treatment of antibiotics for endopthalmitis?
Intravitreal Vancomycin + Amikacin or
Intraviteral Vancomycin + Ceftazidime
What type of antibiotic is amikacin? What type of antibiotic is ceftazidime?
It is an aminoglycoside
It is a cephalosporin
Chorioretinitis is an inflammation of the choroid (thin pigmented vascular coat of the eye) and retina of the eye. Can be caused in AIDS due to cytomegalovrius What is the treatment of CMV?
Ganciclovir
How are eye infections dianosed? (eg bacterial, viral, chlamydial and corneal)
Use swabs for all eye infections apart from keratitis in which you use corneal scrapings
What eye infection can acanthomoeba cause? What should you tell the patient to bring with if this is the case of the scraping?
Seen in fungal causing keratitis
Tell patient to bring their contact lenses with them
Chloramphenical is the most commonly used topical antibiotic for eye infection (ointment or drops) as it treats most bacteria except Pseudomonas aeruginosa For which bacteria is it bacteriostatic or bacteriocidal Staph aureus? H.Influenza? Strep?
Strep and Hinfluenza - is bacteriocidal
Staph aureus is bacteriostatic
What are the three main side effects of chloramphenicol? One is in babies
Can cause allergy
Aplastic anaemia
And grey baby syndrome
Aplastic anemia is a rare disease in which the bone marrow and the hematopoietic stem cells that reside there are damaged. This causes a deficiency of all three blood cell types (pancytopenia) What are the three blood cell losses then?
Red blood cell - anaemia
White blood cell - leukopaenia
Platelets - thrombocytopaenia
Gray baby syndrome (also termed Gray or Grey syndrome) is a rare but serious side effect that occurs in newborn infants (especially premature babies) following the accumulation of antibiotic chloramphenicol.
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What is used for dendritic ulcer treatment? What is the different in strength between this treatment and the one for skin?
Acyclovir is used 3% strength for eye 5% strength for skin
Due to chloramphenicol bein bacteriostatic in staph aureus, what is used to treat this if staph aureus causes bacterial conjunctivits?
Fusidic acid is given
What treatmen can be given to cover most gram negative organsism incuding coliforms?
Gentamicin
What drug is given to treat Chlamydial conjunctivitis? What may adults also need in conjucntion with this for genital chlamydial infection?
Give topical oxytetracylcine for Chlamydial conjunctivitis
Give oral doxycycline in adults for the genital chlamydial infection
A fluoroquinolone will cover most gram negative bacteria including pseudomonas and is used in treating bacterial keratitis What is the alternative treatment option used to treat bacterial keratitis and covers most gram positive and negative bacteria?
Gentamicin + cefuroxime
