Microbiology Flashcards Preview

Year 2 - Ophthalmology (DP) > Microbiology > Flashcards

Flashcards in Microbiology Deck (59):
1

What bacteria commonly cause conjunctivitis in neonates?

Staph. aureus
Neisseria gonorrhoea
Chlamydia trachomatis

2

When do you refer a neonatal bacterial conjunctivitis?

ALWAYS

3

What bacterial commonly cause conjunctivitis in people other than neonates?

Staph. aureus
Strep. pneumoniae
H. influenzae (especially in kids)

4

What topical antibiotic is used in the treatment of bacterial conjunctivitis?

Chloramphenicol qds

5

When should chloramphenicol be avoided?

If history of:
- Aplastic anaemia
- Allergy

6

Yellow-white retinal necrosis and haemorrhage are signs of what?

CMV retinitis

7

CMV retinitis affects what groups of people?

Immunosuppressed:
- Transplant
- Cancer
- HIV

8

What important viral causes of viral conjunctivitis are there?

Adenovirus
HSV
Herpes zoster (Herpes zoster ophthalmicus)

9

Is chlamydial conjunctivitis often acute or chronic?

Chronic

10

When should we suspect chlamydial conjunctivitis?

Bilateral conjunctivitis in young people

11

What other areas may be affected in chlamydial conjunctivitis?

Urethra (Urethritis)
Vagina (Vaginitis)

12

What can chlamydial conjunctivitis lead to?

Follicles
Subtarsal scarring

13

In what type of keratitis is a hypopyon usually seen?

Bacterial

14

What is bacterial keratitis usually associated with?

Other corneal pathology
Contact lens wear

15

How is bacterial keratitis treated?

Admission for hourly drops

16

Which of the following is not a feature of herpetic keratitis:
- Very painful
- Often bilateral
- Can be recurrent
- Results in reduced corneal sensation if recurrent
- Can cause dendritic ulcers

Often bilateral

17

What can happen if herpetic keratitis is treated with steroids?

Corneal melt
Corneal perforation

18

Which of the following is not a feature of adenoviral keratitis:
- Bilateral
- Usually follows an URTI
- Contagious
- Very painful
- May affect vision

Very painful

19

How can recovery be sped up in chronic adenoviral keratitis?

Steroids

20

How can a secondary infection be prevented in adenoviral keratitis?

Topical antibiotics

21

Contact lenses can cause fungal keratitis; what fungi are typically causative?

Acanthamoeba
Pseudomonas

22

Is fungal keratitis more or less indolent than microbial keratitis?

More indolent (Less painful)

23

What is a typical history in a case of fungal keratitis?

Trauma from vegetation

24

A patient presents with a painful right eye that is even worse on eye movements. There is evident exophthalmus. On palpation of the antra, there is tenderness. The patient has a temperature of 39 degrees.

Oribital cellulitis

25

What can CT scans identify in orbital cellulitis?

Orbital abscesses

26

What are potential aetiologies for orbital cellulitis?

- Direct extension from sinus
- Extension from focal orbital infection:
-> Infected chalazion
-> Dacrocystitis
- Post-op

27

Which of the following organisms is not typically responsible for orbital cellulitis:
- Staphylococcus
- Streptococcus
- Coliforms
- H. influenzae
- C. diff
- Pseudomonas
- Anaerobes

Pseudomonas

28

When would radiological imaging be implicated in orbital cellulitis?

If evidence of:
- Muscle restriction OR
- CN II dysfunction

29

How is orbital cellulitis treated?

Broad spectrum IV antibiotics
Drain any abscesses

30

What can cause endophthalmitis?

Surgery
Endogenous
Post-trauma

31

What are some signs and symptoms of endophthalmitis?

PAIN +++
Reduced vision
Very red eye

32

What organisms are commonly implicated in endophthalmitis?

Often eye commensals:
- Staph. epidermidis is the most common

33

How do we treat endophthalmitis?

Intravitreal amikacin and vancomycin
PLUS
Topical antibiotics

34

In what patients does CMV cause chorioretinitis?

HIV patients

35

What is Toxoplasma gondii?

A protozoan infection

36

How does a Toxoplasma gondii chorioretinitis usually present?

Mild flu-like illness

37

If a patient is immunocompetent and suffering from Toxoplasma gondii chorioretinitis, what can happen?

It enters a latent phase and cysts can form

38

How common is Toxoplasma gondii chorioretinitis?

Very:
- 10% of US sample had toxoplasmosis specific IgG

39

If Toxoplasma gondii chorioretinitis is sight threatening, how is it treated?

Systemically

40

What is Toxocara canis?

A parasitic nemotode (roundworm)

41

What happens if Toxocara canis finds host in a human?

Cannot replicate:
- Remains as a larva
- Self limitis

42

What can happen if Toxocara canis chorioretinitis isn't treated

They form granulomas -> Irreversible vision loss

43

When are corneal scrapes carried out?

If bacterial keratitis is suspected

44

When is an aqueous or vitreous sample for culture obtained?

If suspected endophthalmitis

45

How do we investigate acanthamoeba?

Microscopy
Culture

46

With what organisms is serology carried out?

Toxoplasma
Toxocara

47

How does chloramphenicol work?

Inhibits peptidly transferase enzyme:
- Prevents bacterial protein production

48

For what organisms is chloramphenicol bacterocidal and for what organisms is it bacterostatic?

Bacterocidal:
- Streptococcus
- H. influenzae
Bacterostatic:
- Staphylococcus

49

What are side effects of chloramphenicol?

Allergy
Irreversible aplastic anaemia:
- Rare -> 1:40000
Grey Baby Syndrome

50

What antibiotics inhibit cell wall synthesis and how?

Penicillins and Cephalosporins:
- Beta lactam ring prevents enzyme which makes wall

51

What antibiotics inhibit nucleic acid synthesis and how?

Quinolones:
- Inhibit DNA gyrase
- DNA cannot be supercoiled
- Cell death

52

What is a common contaminant in eye swab bottles?

Pseudomonas

53

How does acivlovir work?

Inhibits viral DNA synthesis:
- Base analogue -> Mimics guanine

54

What is aciclovir used to treat?

Corneal dendritic ulcers (instead of steroids)

55

What cause of bacterial conjunctivitis does chloramphenicol not treat?

Pseudomonas

56

What can fusidic acid treat?

Staph. aureus conjunctivitis

57

What bacterial causes of conjunctivitis does gentamicin treat?

Most gram negatives including Coliforms
Pseudomonas

58

What causes of bacterial keratitis does Ofloxacin treat?

Most gram negatives including Coliforms
Pseudomona
H. influenzae
(Not Strep. pneumonia)

59

What causes of bacterial keratitis do gentamicin + cefurozime treat?

Most gram positivies and negatives