Microbiology Flashcards
Which contact lens type poses the highest and lowest risk for microbial keratitis?
- Extended wear, soft, daily disposable, rigid gas permeable
In order from highest to lowest:
Extended wear, soft, daily disposable, rigid gas permeable
Thioglycollate broth
Anaerobic bacteria
Giemsa stain
Fungi
Acanthamoeba
Nutrient free media with E coli
Calcofluor white - fluoresces
Lowenstein Jensen media
TB
Methanamine silver (Grocott)
Fungi
Which 3 bacteria must be grown on chocolate agar?
Neisseria, Haemophilus, Moraxella
Saboraud’s agar
Fungi
What is the most common causative organism for bacterial keratitis?
Pseudomonas aeruginosa
Contact lens wearers at risk - grows on biofilms on contact lenses
What is the treatment for onchocerciasis?
Ivermectin
Treatment for acanthamoeba?
Topical biguanide e.g. propamidine / chlorhexidine
What is the major complication of CMV retinitis?
Retinal detachment (50%)
Treatment for ocular syphillis?
2 weeks IV penicillin G
What is the tetrad for congenital toxoplasmosis?
4 ‘C’s:
- Chorioretinitis
- Microcephaly
- Intracranial calcifications
- Cognitive impairment
Viral and bacterial conjunctivitis - which is more common for adults and children?
Children- bacterial more common
Adults - viral much more common (80%)
Bacterial conjunctivitis - most common pathogens for children and adults
Children - HiB, Strep pneumo, Moraxella catarrhalis
Adults - Staph aureus, strep pneumo, HiB
Viral and allergic conjunctivitis - macroscopic appearance?
Viral: follicular (T-cell response)
Allergic: papillary (collections of inflammatory matter)
Which organisms can penetrate an intact corneal epithelium?
CHNLS Corynebacterium Haemophilus influenzae Neisseria Listeria Shigella
Which TLR recognises mannan and LPS?
TLR-4
What is the role of IL-8?
Potent neutrophil chemoattractant
What does NOD2 recognise?
Peptidoglycan
Most common cause of post-operative endophthalmitis?
Staphylococcus epidermidis (coagulase-negative staph)
Why is IVT amikacin rather than gentamicin used for endophthalmitis?
Gentamicin causes macular necrosis when injected intravitreally
Treatment of endophthalmitis
IVT vancomycin + amikacin / ceftazidime
Recall: ceftazidime is the only cephalosporin with anti-Pseudomonal activity
What anti-TB drug causes Vitamin B6 deficiency?
Isoniazid
Which glycoprotein is used by HSV to enter cells?
Glycoprotein D
Receptors: Nectin, Herpesvirus entry mediator (HVEM)
(HSV has 4 glycoproteins used in cell entry)
Which virus causes Kaposi’s sarcoma?
HHV-8
What genome type does adenovirus have
dsDNA
Ganciclovir and aciclovir - which one for CMV and HSV?
Aciclovir for HSV
Ganciclovir for CMV (CMV is resistant to aciclovir)
What is the latent host cell type for:
- HSV
- VSV
- EBV
- HSV, VSV: neural ganglia
- EBV: B cells (hence post-transplant lymphoproliferative disease is due to proliferation of infected B cells when T cell suppression is removed)
BK and JC viruses are what type of viruses?
Polyomaviruses (dsDNA)
HIV: CD4 counts of below what level place a patient at risk for:
1) TB
2) Toxoplasma
3) CMV retinitis
1) 500 cells/ mm3
2) 200 cells/ mm3
3) 50 cells / mm3
CMV retinitis only occurs in profoundly CD4-depleted AIDS patients
Is subacute sclerosing panencephalitis characterised by mild or florid vitritis?
Mild vitritis - subacute!
What virus is associated with Fuchs heterochromic iridocyclitis?
Rubella
Fuchs –> German –> German measles
Treatment of herpes zoster ophthalmicus
Oral aciclovir - 500mg 5 x/ day
Does not reduce incidence of post-herpetic neuralgia
Staph aureus vs Strep pneumo keratitis: which one is worse?
Strep pneumoniae is worse!
Staph aureus keratitis causes peripheral ulcers and is actually relatively mild compared to pneumococcus and Pseudomonas
