L12 Pathogensis - medically important fungi Flashcards

1
Q

what are fungi

A

eukaryotes

saprophytic or parasitic

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2
Q

what makes fungi eukaroytic

A

nuclear membrane

mitosis

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3
Q

what makes fungi saprophytic

A

live on dead/decaying matter

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4
Q

what makes fungi parasitic

A

live on another organism at its expense

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5
Q

what is the fungal cell wall include

A

firm polysaccharide structure

cell walls - cellulose and chitin

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6
Q

how may fungi exist

A
single cell (yeast)
connecting filaments/hyphae (filamentous fungi/moulds)
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7
Q

size difference between bacteria and fungi

A

fungi 20-50um3

bacteria 1-5um3

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8
Q

cytoplasm difference between bacteria and fungi

A

fungi have mitochondria, ER etc. none in bacteria

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9
Q

cell wall difference in bacteria and fungi

A

fungi have chitin

bacteria have muramic acid

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10
Q

dimorphism difference between bacteria and fungi

A

fungi may be present

not in bacteria

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11
Q

bacteria treatment

A

penicillins

aminoglycosides

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12
Q

fungi treatment

A

azoles

amphoteracin

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13
Q

filamentous fungal growth characteristics

A

filamentous group grow long

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14
Q

yeast fungal growth characteristic

A

budding of daughter

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15
Q

what are the types of fungal reproduction

A

asexual and sexual

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16
Q

what is the asexual fungal reproduction

A

spores singly or multitudes from specialised structures disseminate

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17
Q

what is the sexual reproduction

A

fungi are haploid - meiosis occurs following cell fusion

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18
Q

what is the anti fungal target usually

A

ergosterol

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19
Q

what is a fungal marker for infection

A

beta glucan

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20
Q

what are the fungal pathogen classifications

A

yeasts
yeast like fungi
filamentous fungi
dimorphic fungi

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21
Q

what are yeasts

A

spherical

often budding

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22
Q

example of yeast

A

cryptococcus neoformans

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23
Q

what are yeast like fungi

A

elongated yeasts

pseudomycelia may be seen

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24
Q

example of yeast like fungi

A

candida albicans

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25
Q

what do filamentous fungi form

A

form carpet or layer (mould)

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26
Q

example of filamentous fungi

A

aspergillus fumigatus

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27
Q

what are dimorphic fungi

A

may exist as yeast or filamentous fungi

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28
Q

example of dimorphic fungi

A

histoplasma capsulatum

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29
Q

what is important within medically important fungi

A

frequency
pathogenicity
therapeutics

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30
Q

what diseases does fungi cause

A

superficial
subcutaneous
systemic

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31
Q

examples of superficial fungal infection

A

hair, nails, mucous membranes

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32
Q

what causes superficial infection

A

changes in host resistance and normal flora, or physical contact.
e.g. AB can affect natural flora

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33
Q

examples of subcutaneous infection

A

skin or deeper tissues

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34
Q

what causes subcutaneous infection

A

often soil

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35
Q

what causes a systemic infection

A

inhale fungi

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36
Q

what does systemic infection cause

A

pneumonia or invasion of bloodstream

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37
Q

how are fungal diseases diagnosed

A
clinical suspicion 
microscopy
culture
histology
AB/antigen 
skin test
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38
Q

when is there clinical suspicion of fungal infection

A

fever
unresponsive to antibacterials
meningitis/pneumonia in immunocompromised

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39
Q

microscopy examples

A

gram stain
india ink
wet prep

40
Q

how are superficial infections diagnosed

A

visual or skin scrape for microscopy

41
Q

how are systemic infections diagnosed

A

blood culture
tissue (e.g.lung biopsy)
serology
antigen detection

42
Q

what are yeast like fungi like

A

opportunistic pathogen

43
Q

where are yeast like fungi present

A

GI and respiratory flora

44
Q

who are predisposed to overgrowth/infection of yeast like fungi

A
diabetes mellitus
malignancy
neutropenia
defects in cell-mediated immunity
trauma
drugs e.g. antibacterials, corticosteroids, contraceptive pill
45
Q

where can candida infect

A
usually thrush 
eyes
spleen
liver 
etc
46
Q

how is dissemianted candidiasis detected

A

use imaging of chest but cant detect the infection but see infected

47
Q

where do filamentous fungi infect

A

keratinous tissues of hair, naols, skin

48
Q

how are filamentous fungi diagnosed

A

clinical

scrapings for microscopy and culture

49
Q

what is the treatment for filamentous fungi

A

clotrimazole

terbinafine

50
Q

what is tinea capitis

A

filamentous fungi infection

51
Q

what does tinea capitis cause

A

head infection
hair loss
flaky skin

52
Q

what does tinea pedis cause

A

atheletes foot
inflammatory reaction
swelling

53
Q

what does tina unguium cause

A

chronic nail infection difficult to get rid of

54
Q

where are aspergillus fumigatus present

A

ubiquitous spores

soil dust

55
Q

what illness does aspergillus fumingatus cause

A

pulmonary
systemic
other e.g. sinusitis, endocariditis

56
Q

pulmonary effects of aspergillus fumingatus

A

asthma, aspergilloma (fungal ball), can be invasive

57
Q

where can aspergillus fumingatus infect when systemic

A

lung
renal
cerebral

58
Q

what is the aspergillus fumingatus treatment

A

iv voriconazole or Amphoteracin B (Liposomal) / po Itraconazole voriconazole

59
Q

what is the effect of liposomal amphotericin b to normal

A

allow higher doses without being too toxic to kidneys

60
Q

what fungi is aspergillus fumigatus

A

filamentous fungi

61
Q

what fungi is crytococcus neoformans

A

true yeast

62
Q

where is crytococcus neoformans present

A

environment - soil, bird poo

63
Q

what is crytococcus neoformans

A

opportunistic pathogen

64
Q

who are predisposed to crytococcus neoformans

A

defects in cell-mediated immunity (low CD4+ T-cells)

65
Q

what are the clinical consequences of crytococcus neoformans

A

meningitis in HIV/cancer patients
pulmonary disease
disseminates quickly
pulmonary infection can be asymptomatic but spread from lungs

66
Q

how can crytococcus neoformans be diagnosed

A

clinical suspicion
microscopy
culture
antigen detection

67
Q

what are the clinical suspicions of crytococcus neoformans

A

signs + symptoms; e.g. meningitis in an HIV patient

68
Q

what stain is used for crytococcus neoformans

A

india ink stain

69
Q

what sample is used for crytococcus neoformans microscopy

A

CSF

70
Q

what sample is used for crytococcus neoformans culture

A

CSF

blood

71
Q

what sample is used for crytococcus neoformans antigen detection

A

CSF

blood

72
Q

what is the treatment for cryptococcus neoformans

A

iv Amphoteracin B (Liposomal) +/- 5-flucytosine

73
Q

why is cryptococcus neoformans difficult to eradicate

A

the infection can sequester in different areas of body

74
Q

what is used to prevent cryptococcus neoformans relapse

A

po fluconazole maintenance

75
Q

what can you detect c. neoformans in

A

CSF

bood

76
Q

what does a cryptococcal pulmonary infection look like on xray of chest

A

cant see it is cryptococcus need to grow from biopsy or sputum

77
Q

what fungi is pneumocystis jiroveci

A

atypical fungus related to yeasts

78
Q

why was pneumocystis jiroveci reclassified from a protozoan

A

cell wall composition; ribosomal RNA gene sequence

79
Q

why is pneumocystis jiroveci difficult

A

cannot be grown in vitro
difficult to study
cant do sensitivity tests

80
Q

why was pneumocystis jiroveci originally a protozoa

A

does not respond to conventional anti-fungal agents

81
Q

what is pneumocystis jiroveci

A

opportunistic pathogen

82
Q

what can pneumocystis jiroveci cause

A

pneumonia

83
Q

how is pneumocystis jiroveci diagnosed

A

microscopy/cytology of bronchoalveolar lavage

84
Q

what is pneumocystis jiroveci treatment

A

co-trimoxazole

pentamidine

85
Q

what does pneumocystis pneumonia look like on chest xray

A

black background is hazy

86
Q

what is PCP

A

pneumocystis pneumonia

87
Q

what does the histology of pneumocystis pneumonia show

A

foamy exudate fills alveolar spaces

88
Q

what is pneumocystis pneumonia like - fluorescent monoclonal AB

A

cysts appear apple green

89
Q

what is pneumocystis pneumonia like on silver stain

A

cysts are black

90
Q

what is the pneumocystis pneumonia diagnosis

A

now usually by PCR on throat swabs / respiratory samples or EDTA blood

91
Q

where is histoplasma capsulatum present

A

mould in environment

yeast in tissues

92
Q

where is histoplasma capsulatum common

A

eastern/central USA

93
Q

what is the histoplasma capsulatum treatment

A

iv Amphoteracin B

94
Q

what are the clinical effects of histoplasma capsulatum

A

asymptomatic
acute/chronic respiratory infection
disseminated disease (liver, lungs, spleen) – esp. in HIV +ve patients

95
Q

where are histoplasma capsulatum in the body

A

macrophages as yeast