pathogenesis of infectious disease Flashcards Preview

Therapeutics > pathogenesis of infectious disease > Flashcards

Flashcards in pathogenesis of infectious disease Deck (106):
1

list 4 possible ocular diseases/infections from ascending order of severity that can be caused by pathogens

- periocular and orbital
- keratitis
- uveitis
- endophthalmitis

2

what can the exposed condition of the ocular service implicate about disease and how does this not happen as often as thought

the exposed condition of the ocular surface means it is frequently in contact with disease causing micro-organisms, however the ocular surface has many defence mechanisms to ensure that it remains disease free including:
- anti-microbial properties of the tears
- constant shedding of the cells from the ocular surface

these reduce contact time with the pathogen and a number of affective immunological mechanisms

3

name 3 risk factors that can predispose the eye to infections

- patients immune status
- ocular morbidity
- contact lens wear

4

list 5 potential pathogens that can cause infection of the cornea

- bateria
- HSV
- VZV
- protozoa
- fungi

5

list 4 potential pathogens that can cause infection of the uvea

- bacteria
- CMV
- VZV
- protozoa

6

list 2 potential pathogens that can cause endophthalmitis

- bacteria
- fungi

7

which potential pathogen can cause infection of the orbit

bacteria

8

list 5 potential pathogens that can cause infection of the lids and conjunctiva

- bacteria
- chlamydia
- adenovirus
- HSV
- VZV

9

what are the 2 least common pathogens to affect the eye

fungi and protozoa

10

where in the eye are microbial flora usually present and since when

- on the eyelids and in the conjunctiva sac
- from birth and are present throughout the life

11

what are these harmless microbial flora called

commensals

12

what type of non-pathogenic microbes make up the microbial flora and which microbes less commonly make up the microbial flora

- most commonly gram +ve bacteria
- less commonly environmental fungi and viruses

13

which parts of the eye are there no microbes/commensals at all

- cornea
and
- anterior chamber

are sterile

14

what do the commensals found on the eyelid and conjunctiva form

part of the innate defence system of the eye, they compete with potential pathogens for essential nutrients

15

what 3 classes of bacteria make up the normal conjunctival and eyelid flora

- gram +ve cocci (sphere shape)
- gram +ve bacilli (rod shaped)
- anaerobic

16

list the 3 types of gram +ve cocci commensal bacteria

- staphylococcus epidermis 30-80%
- staphylococcus aureus 3-25%
- micrococcus sp. 1-28%

17

which bacterial commensal accounts for 30-80% of the conjunctiva and lids

gram +ve staphylococcus epidermis

18

which bacterial commensal accounts for 3-25% of the conjunctiva and lids

gram +ve staphylococcus aureus

19

which bacterial commensal accounts for 1-28% of the conjunctiva and lids

gram +ve micrococcus

20

what is the name of the gram +ve bacilli commensal bacteria found on the conjunctiva and lids

corynebacterium species 5-83%

21

which gram +ve bacterial commensal accounts for 5-38% of the conjunctiva and lids

grame +ve bacilli corynebacterium species

22

what is the name of the anaerobic commensal bacteria found on the conjunctiva and lids

propionibacterium sp. 0-33%

23

which bacterial commensal accounts for 0-33% of the conjunctiva and lids

propionibacterium (anaerobic)

24

when can all the commensal bacteria found on the conjunctiva and eyelids cause disease

in particular circumstances when they are found in high concentration

25

list three peri ocular structures which can get infected

- eyelids
- conjunctiva
- lacrimal system

26

name 2 orbital infections

- orbital cellulitis
- pre septal cellulitis

27

name a peri-ocular infection of the eyelid

external hordoleum (stye)

28

what is a external hordoleum (stye) found on the eyelid an infection of

- the ciliary sebaceous gland (zeis)
- typically staph. aureus

29

what form of treatment is needed to treat a external hordoleum (stye)

most commonly warm compresses
topical antibiotics if needed

30

what else has to be affected as well as the gland of zeis for the infection to be a internal hordoleum

meibomian glands

31

what are the signs and symptoms associated with a external hordoleum (stye)

- lid swelling
- lid tenderness
- collection of pus under the skin

32

name a peri-ocular infection of the eyelid other than a external hordoleum (stye)

blepharitis - inflammation of the eyelids

33

what are the 2 forms of blepharitis

chronic or remitting

34

what 2 aetiologies can blepharitis have

infective or non-infective (often)

35

what are the 2 infectious organisms that cause blepharitis

- staph, aureus
- staph epidermis

36

what is the treatments of blepharitis

- eyelid hygiene alone
- may require topical antibiotics

37

what are the characteristics of the staphylococci bacteria

- commensals of human skin
- gram +ve cocci (clumps)
- grow on most media

38

what is the spectrum of disease caused by staphylococci bacteria

- can be local such as conjunctivitis or deep infection as it can penetrate into deeper tissues
- can cause toxin mediated disease, where it produces damage primarily through the production of toxins which are cytotoxic for cells and can cause harm

39

what are the signs of pre septal cellulitis that differentiates it from orbital cellulitis

normal vision and no pupillary defect

40

what are the signs of orbital cellulitis that differentiates it from pre septal cellulitis

- ophthalmoplegia (down and out)
- pupillary defect/RAPD
- proptosis
- pain
- painful eye movements

41

what can orbital cellulitis arise from

abscess in the ethmoid sinus and less commonly the maxillary and frontal, which spreads into the orbit

42

who is orbital cellulitis more commonly found in

children

43

where can the infection of orbital cellulitis spread to which makes it sight and life threatening

to the cranial cavity
as there is direct connection between the orbit and the cranium

44

where does the septum run

from the orbital margins to the tarsal plates

45

how many orbital infections does pre septal cellulitis account for

94% (most common)

46

how many orbital infections does orbital cellulitis account for

6%

47

what is pre septal cellulitis and orbital cellulitis both more common in and why how much

in children 75% in

48

what are the 2 aetiologies of pre septal cellulitis

- sinusitis in 80-90% of cases
- strep. pneumoniae / H.influenza

49

what is used in the diagnosis of an orbital infection

CT scan is the most helpful in DDX

50

what is the treatment for pre septal cellulitis

antibiotics
against potential causative organisms such as, staph aureus, strep pneumonia or H. influenza

51

what is the treatment for orbital cellulitis

drainage of abscess and concurrent IV antibiotics

52

name the 3 characteristics of the bacteria streptococci

- commensals of mouth/gut
- gram +ve cocci (chains)
- grows on blood agar (haemolysis)

53

what is the spectrum of disease of the bacteria streptococci

- wide
- local (conjunctivitis) to systemic infections (pneumonia or meningitis)
- toxin mediated disease

54

what distant appearance does the bacteria streptococci cause on an agar plate

they cause a clear zone called haemophilus

55

what are three characteristics of haemophilus spp

- commensal of URT
- gram negative rod
- fastidious (grows on chocolate agar = a variant of blood agar)

56

haemophilus spp are ____________ pathogens who live in the ______ without causing __________ but with reduced __________ functions or ___________ inflamed tissues cause _____________ for it to cause ___________

haemophilus spp are opportunistic pathogens who live in the host without causing disease but with reduced immune functions or chronically inflamed tissues cause opportunity for it to cause infection

57

what is the spectrum of disease of the bacteria haemophilus spp

- much less since vaccination
- local infection (sinitis or conjunctivitis) to meningitis or pneumonia

58

which group of patients is conjunctivitis most common in

children

59

which 3 pathogens can present as conjunctivitis

- viral
- bacterial
- chlamydial

60

what evaluation is often not done with conjunctivitis and why

lab can be done but isn't done as much because conjunctivitis is self limiting

61

when will you carry out a scraping/swab of conjunctivitis on a patient and why

only done on ophthalmia neonatorium (if contract in 1st month of life) as they need to be referred for intensive treatment

62

what type of conjunctivitis do girl and chlamydial pathogens cause

characteristic follicular conjunctivitis

63

what are the characteristics of bacterial conjunctivitis

- incidence is unknown
- rapid onset
- unilateral, but bilateral after 1-2 days

64

name the bacteria involved acute in conjunctivitis in adults and children

staphylococcus aureus

65

name the bacterias involved in acute conjunctivitis in children only

- strep. pneumo
- H. influenza

66

name the bacteria involved in chronic conjunctivitis

- due to endotoxins
- staphylococcus aureus
- moraxella
- enterobacteriacae

67

what may be difficult with chronic conjunctivitis

to eradicate it

68

what other conditions is viral conjunctivitis commonly associated with

cold and flu

69

what is the most common form of conjunctivitis

viral

70

what are the characteristics of viral conjunctivitis

- acute
- unilateral but bilateral after 1 week
- often also get pre-auricular nodes
- self limiting - recovery after a few days only
- usually no sequelae

71

which virus is viral conjunctivitis caused by

adenovirus

72

what are the 2 variations of viral conjunctivitis

- pharyngoconjunctival fever
- epidemic keratoconjunctivitis

73

which adenovirus serotypes is pharyngoconjunctival fever variation of viral conjunctivitis caused by and what is this type characterised by

3, 4 and 7
characterised by pre auricular lymph node enlargement in 90% of cases

74

which is the commonest type of viral conjunctivitis

pharyngoconjunctival fever

75

after how long does the pharyngoconjunctival fever variation of viral conjunctivitis resolved

within 2 weeks

76

which form of viral conjunctivitis is more severe

epidemic keratoconjunctivitis

77

how long does epidemic keratoconjunctivitis type of viral conjunctivitis last

1-3 weeks

78

what 2 things is associated with epidemic keratoconjunctivitis type of viral conjunctivitis

- subconjunctival haemorrhage in 33% of cases
- may get corneal involvement - sub epithelial infiltrates in 20-30% of cases

79

which adenoviral serotypes is epidemic keratoconjunctivitis type of viral conjunctivitis caused by

8, 11 & 19

and produces a mixed papillary and follicular conjunctival response

80

what type of virus is the aden virus

a DNA virus
with 49 serotypes

81

which 2 ways is the adenovirus spread

- fomites (virus can survive in inanimate objects)
- contact with secretions e.g. following cough or sneeze

82

what are the 2 forms of chlamydial conjunctivitis

- trachoma
- follicular conjunctivitis

83

what 2 things is trachoma due to

- poor sanitation
- multiple untreated infections which is endemic in developing countries due to over crowding

84

what can trachoma cause

- palpebral conjunctival scarring
- entropion
- in some cases ectropion
- ulceration and corneal scarring (due to result of corneal exposure)

85

what is the treatment os trachoma associated with chlamydial conjunctivitis

antibiotics:
- tetracyclines
and
- erythromycin

86

what causes acute inclusion conjunctivitis form of chlamydial conjunctivitis

- chronic follicular conjunctivitis
- usually sexually transmitted

87

what is the presentation of chlamydial conjunctivitis

- unilateral red eye
- usually mild/diffuse
- may involve the cornea, producing punctate keratitis (& lesions similar to viral conjunctivitis)

88

what are the characteristics of the pathogen chlamydiae

- obligate intracellular parasite
- depend on host cell
- inert infectious particles
- culture not routine (but can be cultured by conjunctival scrape)

89

which 3 ways can you diagnose the pathogen chlamydia

- serology
- histology (inclusions)
- PCR

90

how is a conjunctival scrape carried out for detecting chlamydia

- using a kamura spatula
- sample taken from upper and lower conjunctival sac
- sample is then placed on a slide and under a microscope to identify the characteristic inclusion bodies

91

what are the varieties of culture media

- chocolate (aerobic and anaerobic)
- blood agar
- Mc conkey agar (coliforms)
- sabouranaud dextrose (fungi)

92

which agar is used for particular gram -ve organisms e.g. E coli

Mc conkey agar (coliforms)

93

how is antibiotic sensitivity tested

- by impregnating antibiotics onto paper discs
- placed on an agar plate
- bacteria are not able to grow around anti-biotics to which they're sensitive
- by measuring their zones of inhibition around the discs will identify the most relevant antibiotic treatment for a infection

94

list the 4 types of keratitis and what micro organism causes each one

- bacterial - pseudomonas
- viral - herpes simplex
- fungal - fusiform
- protozoal - acanthamoeba

95

what is contact lenses the biggest risk for

bacterial and acanthamoeba keratitis

96

what are the 4 classifications of uveitis

- anterior
- intermediate
- posterior
- panuveitis

97

what are the aetiologies of uveitis

- infectious
- non-infectious

98

what is infected in uveitis

any part of the uveal tract e.g. iris, ciliary body or choroid, either individually or collectively

99

what are the 2 infectious aetiologies of anterior uveitis

- herpes simplex virus HSV (most common cause)
- varicella zoster virus VZV

100

what are the 4 infectious aetiologies of posterior uveitis

- toxoplasmosis (parasite)
- toxocara
- syphilis
- cyclomagalovirus CMV

101

which type of posterior uveitis does cyclomagalovirus CMV cause and which patients is this seen in

choroiditis and associated retinitis
seen in immunosuppressed individuals e.g. AIDS

102

what are the characteristics of endophthalmitis

- usually bacterial and acute
- in most cases due to exogenous bacteria that the internal structures is exposed to (due to surgery or trauma)

103

what are the 4 classifications of endophthalmitis

- acute post cataract
- chronic pseudophakic
- bleb-related
- post traumatic

104

from where in the eye can infected samples of edophthalmitis be taken from

- aqueous humour
- vitreous humour

105

what does the college of optometrist provide

its infection control guidance

106

what 6 principles of infection control does the college of optometrists provide

- principles of cleaning sterilisation and infection
- hand hygiene
- situations of greater risk
- contact lenses and ophthalmic devices such as tonometer heads
- contamination via contact lens solutions and medicine bottles
- safe disposal waste