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Drug Action IV > Fungi (Patho) - Block 3 > Flashcards

Fungi (Patho) - Block 3 Flashcards

1
Q

What type of organisms are fungi?

A
  1. Eukaryotic
  2. Heterotrophic
  3. Ubiquitous
  4. Obligate aerobes or facultative anaerobes
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2
Q

What are the morphologic forms of fungi?

A
  1. Yeasts (single cell)
  2. Mold (filamentous, multicellular)
  3. Dimorphic (switch between yeasts and molds)
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3
Q

Describe the components of a fungal cell structure?

A
  1. Membrane bound organelles
  2. Eukaryotic nucleus
  3. DNA
  4. Ribosomes are 80s (40s and 60s)
  5. Vacuole
  6. Enclosed by rigid cell wall
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4
Q
A
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5
Q

What is the function of vacuole?

A

Enclosed compartment containing water, nutrients, and enzymes that helps maintain pH and contain waste

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6
Q

What is the function of the cell wall?

A

Protects cells from osmotic shock, determine cell shape, and contains antigenic components

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7
Q

What are the components of a cell wall?

A
  1. Mannoproteins
  2. Glucans
  3. Chitin
  4. Cell membrane
  5. Ergosterol
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8
Q

What is the function of mannoproteins?

A

GLycosylated mannose allowing it to adhere to host cells

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9
Q

What is glucans?

A

Major component of cell wall: Branched b-(1,3)-glucan and b-(1,6)-glycan synthesized by b-(1,3)-glucan synthase in the cell membrane and exported to cell wall

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10
Q

What is chitin?

A

Long chain polymer of NAG -> produced by chitin synthase in cell membrane

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11
Q

What are the components of a cell membrane?

A
  1. Lipid bilayer that is selectively permeable
  2. Integral proteins
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12
Q

What is the dominant fungal sterol?

A

Ergosterol

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13
Q

How are yeast formed?

A
  1. Reproduce asexual budding or fission
  2. Mother cell elongates and pinches off forming a progeny cell
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14
Q

What is the structure of mold?

A
  1. Tubular (filamentous) multiceulluar
  2. spore formation (sexual or asexual resproduction)
  3. Long filaments (hyphae)
  4. Mycelium: matlike mass of hyphae
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15
Q

What is the difference between septate and non septate hyphae?

A

Septate: divided by cross walls
Non: lack cross walls, hollow

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16
Q

What are the functions of spores?

A
  1. Reproductive structures
  2. Help fungi spread and colonize
  3. Cause infection
  4. Provide resistance
  5. Metabolically dormant
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17
Q

What is a dimorphic fungi?

A

Capable of converting between yeast and mold forms in different temperatures
* Molds at ambient temp
* Yeast at body temp

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18
Q

Most damage due to fungal infection or indirect or direct?

A

Indirect:
1. Activation of macrophages and neutrophils
2. Activation of proinflammatory T helper cells
3. Antibodies are generated against cell wall components

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19
Q

What is the immune response to fungal infections?

A

Macrophages recognize PAMPS on fungal cell wall and secrete cytokines that activate T cells and neutrophils

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20
Q

What is cutaneous mycoses?

A
  1. Confined to epidermis
  2. Involved in keratinized tissue
  3. Dermatophytes
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21
Q

What is subcutaneous mycoses?

A
  1. Infection in the deeper layers of skin
  2. dermis, cornea, muscle, bone, and connective tissue
  3. Acquired from traumatic inoculation
  4. Localized
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22
Q

What is endemic mycoses?

A
  1. Caused by dimorphic fungi
  2. Confined to geographic regions
  3. Blastomyces, Histoplasma, Coccidioides
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23
Q

What are opportunistic mycoses?

A
  1. Caused by commensal fungi or fungi found within the environment
  2. Limited virulence
  3. Target IC patients
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24
Q

Mycoses that is caused by dermatophytes?

A

Cutaneous

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25
Q

How is cutaneuos mycoses transmissed?

A

Warm, moist environment transferred person to person

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26
Q

Presentation of dermatophytoses?

A

Itching, scaling skin patches that become inflamed and weeping

27
Q

Tinea pedis

A

Atheletes foot

28
Q

Tinea corporis

A

Ringworm

29
Q

Tinea capitis

A

Scalp ringworm

29
Q

Tinea cruris

A

jock itch

30
Q

Tinea unguium

A

onychomycosis: nails to thicken, discolor, and become brittle

31
Q

Describe the activity of Candidia?

A

Yeast that can become disseminated into the blood:
1. Breakdowns in mucosal barriers, biofilm formation
2. Cause infection in heart valves, liver, spleen, bones, kidney
3. Fever, chills, hypotension, altered mental status

32
Q

Opportunistic fungi?

A

Candidia
Cryptococcus neoformans
Aspergillus
Pneumocystic jirovecii

33
Q

Types of Candida albicans?

A
  1. Vulvovaginal candidiasis (vaginitis)
  2. Oral candidiaisis (thrush)
  3. Candida albicans develops pseudohyphae to invade tissues (dimorphic)
34
Q

What is the cause of pseudomembranous candidiasis?

A

Overgrowth and development of pseudohyphae damaging stratified squamous epithelial layer
* Desaquamation and keratin protein buildup causing a psuedomembrane and red painful lesions

35
Q

What is the structure of cyrptococcus?

A

Yeast surrounded by a polysaccharide capsule

36
Q

How is cryptococcus transmitted?

A

Pigeon dropping and soil associated with eucalyptus:
* Inhalation of yeast
* Percutaneuos inoculation
* Opportunistic

37
Q

What is the differenc between Cryptococcal pneumonia and meningitis?

A

Pneu: mild or asymptomatic contained in LN -> granulomas
Men: causes HA and photophobia, personality changes, fatal, Aid-defining condition

38
Q

Describe the structure of Aspergillus?

A

Filamentous mold (septate mycelium with conidia)

39
Q

Transmission of Aspergillus?

A

Inhalation of airborne spores from conidia and transferred to wounds by contaminated bandages

AIDs defining codnition

40
Q

What is Aspergeillosis?

A

Opportunistic and systemic mycoses -> infection in skin, eyes, ears, sinuses

41
Q

Presentations of allergic aspergillus sinusitis?

A

Chrnic rhinosinusitus that causes asymmetrical swelling around the orbit and nasal sinuses

42
Q

What pathogen forms a fungal ball in the lungs?

A

Aspergillus (aspergilloma)

43
Q

Populations that contract chronic pulmonary aspergillosis?

A

Chronic lung disease

44
Q

What is the pathogen that lacks ergsterol?

A

Pneumocytis

45
Q

Transmission of pneumocystis?

A

Portal of entry: respiratory tract
Opportunistic mycoses in IC patients (AIDs defining condition) -> PCP

46
Q

How does pneumocystitis cause pneumonia?

A

Forms cysts in the lungs and ruptures releasing fungi:
1. Attach to alveolar epithelial cells
2. Induce inflammation -> foamy exudate blocking O2 exchange
3. Symmetrical bilateral interstitial infiltrates -> death from respiratory failure

47
Q

What pathogen is known as Cavers?

A

Histoplasma capsulatum

48
Q

What is the most common systemic mycoses in US?

A

Histoplasma capsulatum (Caver’s Disease)

49
Q

Describe the strucutre of histoplasma?

A

Dimorphic fungal pathogen that forms spores

50
Q

Transmission of histoplasma?

A

Inhalation of spores founds on feces

51
Q

Presntation of histoplasmosis?

A

Pneumonia:
1. granuloma with calcifications
2. Acute infection
3. Aymptomatic
4. Disseminated liver, spleen, LN, BM (IC patients)

52
Q

Clinical lab tests for histoplasmosis diagnosis?

A
  1. Antigen immunoassays
  2. Microscopy of fluids/tissue samples with narrow-based buds
53
Q

Structure of Blastomyces?

A

Dimorphic pathogen in soil

54
Q

Transmission of blasstomyces?

A

Inhalation of mold (conidia or hyphal fragments) infecting skin, bone, GU, CNS

55
Q

How does blastomyces evade immune response?

A
  1. Adhere to resp mucosa and trasform to yeast
  2. Yeast sheds major surface antigen to avoid detection by macrophages
56
Q

Dx caused by blastomyces?

A
  1. Pulmonary blastomycosis dx
  2. Disseminated dx in IC
57
Q

Lab testing for blastomyces?

A

Culture of biopsy or sputum

58
Q

Systemic pathogens can cause disease in healthy and immune-compromised individuals

A

Histoplasma
Blastomyces
Coccidioides

59
Q

Opportunistic pathogens can cause mycoses in immune-compromised individuals

A

Aspergillus
Candida
Cryptococcus
Pneumocystis

60
Q

What is the structure of coccidiodes?

A

Dimorphic

61
Q

Transmission of coccidiodes?

A

Inhalation of mold carried to deep lungs producing endospores

62
Q

How does coccidioides evade immune response?

A
  • Phagocytosed by macrophages but escapes destruction by increasing pH of phagosome (urease)
  • Produces proteases and collagenases -> breaching of mucosal barriers -> disseminated coccidioidomycosis
63
Q

Lab testing used for coccidioides?

A

Detection of IgG and IgM antibodies and NAAT assays

Drug Action IV (28 decks)

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