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CP reviewer 1 > Fungal Pathogens > Flashcards

Fungal Pathogens Flashcards

1
Q

What are fungi?

A
  • Separate kingdom of organisms - Eukaryotic microorganisms
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2
Q

What are the 2 major fungal growth modes?

A
  1. Yeast cells = yeast 2. Hypha (moulds)
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3
Q

Is yeast single or multicellular? Hyphae?

A

Yeast = single-celled Hyphae = multicellular

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4
Q

How do fungi reproduce?

A

Reproduce asexually and/or sexually, spore formation

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5
Q

What are the 3 main life styles of fungi?

A
  1. Saprophytes 2. Plant pathogens 3. Animal pathogens
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6
Q

What are saprophytes?

A

a plant, fungus, or microorganism that lives on dead or decaying organic matter.

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7
Q

What are the 3 types of fungal disease?

A
  1. Superficial infection 2. Subcutaneous infection 3. Systemic infection
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8
Q

What do superficial infections affect?

A

skin, hair, nails and mucocutaneous tissue

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9
Q

What do subcutaneous infections affect?

A

affecting subcutaneous tissue, usually following traumatic implantation

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10
Q

What do systemic infections affect?

A

Deep-seated organs

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11
Q

Dermatophytes:

  • Mould or yeast?
  • What type of infections do they cause?
  • What do they require for growth?
A
  • Mould
  • Superficial (skin, hair, nail)
  • Keratin
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12
Q

Where do dermatophytes originate?

A

Soil, other animals or other humans

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13
Q

How are dermatophytes classified?

A

In terms of where they originate from

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14
Q

If dermatophytes come from: a) soil b) other animals c) other humans what are they called?

A

a) geophilic b) zoophilic c) anthropophilic

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15
Q

Disease name (medical AND colloquial) for dermatophyte infections according to their site:

What is the prefix?

a) foot skin
b) nail (toe or finger)
c) groin area skin
d) limbs and torso skin generally
e) scalp skin and hair

A

Prefix is tinea-

a) tinea pedis –> athletes foot
b) tinea unguium –> fungal nail disease
c) tinea cruris –> jock itch
d) tinea corporis –> ringworm
e) tinea capitis –> scalp ringworm

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16
Q

How common are fungal nail infections?

A

common in the general adult population, probably 5-25% rate, increasing incidence in elderly people

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17
Q

Who is athletes foot seen mostly in?

A

more common than onychomycosis, more common in adults (not younger people) and sportsmen

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18
Q

Who is scalp ringworm most common among?

A

most common among prepubertal children.

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19
Q

Signs and symptoms of atheletes foot

A
  • Uni- or bilateral,
  • Itching, flaking, fissuring of skin
  • Plantar: Soles of feet dry and scaly, if skin of whole of foot affected “Moccasin foot”
  • Hyperhidrosis, secondary to infection may increase severity
  • May spread to infect toe nails
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20
Q

Which organism typically causes atheletes foot?

A

Dermatophyte –> ‘trichophyton rubrum’

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21
Q

What are the 4 main types of fungal nail infection (tinea unguium)?

A

Thickening, discolouring, dystrophy:

  1. Lateral/distal subungual
  2. Superficial white – usually in immunocompromised
  3. Proximal nail edge
  4. Total nail dystrophy
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22
Q

Which organisms typically cause tinea unguium (fungal nail infection)?

A

Trichophyton rubrum and T. interdigitale (both dermatophytes)

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23
Q

Who is tinea cruris (jock itch) seen more in?

A

More prevalent in men than women

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24
Q

Signs and symptoms of tinea cruris (jock itch)?

A
  • More prevalent in men than women
  • Itching, scaling, erythematous plaques with distinct edges
  • Satellite lesions sometimes present
  • May extend to buttocks, back and lower abdomen
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25
Q

Which organism typically causes tinea cruris (jock itch)?

A

T. rubrum (dermatophyte)

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26
Q

Signs and symptoms of tinea capitis (scalp ringworm)?

A
  • Signs range from: slight inflammation, scaly patches, with alopecia, “black dots”, “grey patches” to severe inflammation
  • In areas of severe inflammation you can get Kerion celsi
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27
Q

What are Kerion celsi? What does it look like? What type of dermatophytes has usually caused this?

A
  • A severe inflammatory form of tinea capitis that is characterised by a T-cell-mediated hypersensitivity reaction against dermatophyte fungi.
  • Boggy, inflamed lesions, usually from zoophilic dermatophytes
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28
Q

Typical scalp ringworn in baby

A
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29
Q

Typical presentation of tinea corporis (ringworm)?

A
  • Circular, single or multiple erythematous plaques
  • May extend from e.g. scalp or groin
  • Invasion of follicle “Majocci’s granuloma”
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30
Q

Which organisms typically cause tinea corporis (ringworm)?

A

Typical cause, wide range of dermatophytes, anthropophilic or zoophilic

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31
Q

Investigation of dermatophyte infections?

A

Microscopy and culture

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32
Q

In non severe cases, how would dermatophyte infections be treated? What medications can be used for this?

A
  • Topical antifungal therapy: mild disease (self diagnosis and treatment)
  • Terbinafine, clotrimazole, miconazole
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33
Q

How are severe cases of dermatophyte infection treated?

A

Systemic antifungal therapy

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34
Q

What should ALL cases of tinea capitis be treated with? Why?

A

Systemic oral antifungals as topical therapy will NOT be curative (only has role in reducing spread)

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35
Q

Which drugs are used in the treatment of systemic fungal infections?

A
  • Griseofulvin, terbinafine, itraconazole (depends on causal species)
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36
Q

Malassezia:

a) Mould or yeast?
b) Where is it naturally found?
c) 3 examples?
d) What diseases does it have a role in?

A

a) Genus of yeats
b) Part of normal skin flora in all humans from shortly after birth - highest levels on head and trunk
c) M. sympodialis, M. restricta and M. globosa
d) Pityriasis versicolor, seborrhoeic dermatitis and atopic eczema

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37
Q

What is Pityriasis versicolor? What is it caused by?

A
  • A common fungal infection that causes small patches of skin to become scaly and discoloured
  • Caused by Malassezia.
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38
Q

Typical presentation of pityriasis versicolor?

A
  • Hyper- or hypopigmented lesions (mainly on upper trunk)
  • Between puberty and middle age
  • More common in tropics
  • Relapsing disease
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39
Q

Diagnosis of pityriasis versicolorvia microscopy?

A
  • Yeast cells and hyphal segments “Sphagetti and meatballs”
  • Culture difficult and not interpretable
40
Q

Treatment of pityriasis versicolor?

A
  • Topical antifungals e.g. clotrimazole
  • If fails, oral antifungals e.g. fluconazole or itraconazole
41
Q

Candida:

  • Yeast or mould?
  • Where is it normally found?
  • What type of infections can it cause?
  • 4 examples of species?
A
  • Large genus of yeasts
  • Often colonises the mucosal sufaces and GI tract in healthy people
  • Cause of superficial mucosal (oral and vaginal) disease “thrush”, also occasionally skin disease and keratitis
  • Cause of systemic disease, once present in circulatory system, can infect almost any organ in the body

–Candida albicans

–Candida glabrata

–Candida parapsilosis

–Candida krusei

42
Q

Candida can cause superficial infection of the oral mucosa. What are the 4 types?

A
  1. Acute pseudo-membranous
  2. Chronic atrophic
  3. Angular cheilitis
  4. Chronic hypoplastic
43
Q

What is acute pseudomembranous candidiasis? Who is it typically seen in?

A
  • A classic form of oral candidiasis, commonly referred to as thrush
  • Typically seen in:
    • those with a low CD4 count (AIDS patients NOT on treatment)
    • younger patients
    • asthma with steroid inhalers
44
Q

What is chronic atrophic candidiasis? Who is it typically seen in?

A
  • Erythema (redness of the skin or mucous membranes - seen in infection)
  • Typically seen in older patients
45
Q

What is angular cheilitis?

A
  • Inflammation of corners of mouth
46
Q

What is chronic hyperplastic candiasis? What is it characterised by?

A
  • A variant of oral candidiasis
  • Lesions may undergo malignant transformation
47
Q

Which patients is oral candidosis most commonly seen in?

A
  • HIV/AIDS
  • Antibiotic use
  • Head and neck cancer
  • General debiliation in hospitalised patients
48
Q

Why is oral candidosis more commonly seen in HIV/AIDS patients?

A

Sometimes even with anti-retroviral therapy, T-cell immunity is important to prevent mucosal candidosis

49
Q

Why can antibiotic use lead to oral candidosis?

A

Suppresses normal bacterial flora –> less competition for yeasts

50
Q

Why can head and neck cancer patients lead to oral candidosis?

A

Radiotherapy and chemotherapy affects salivary secretions which would otherwise suppress candida infection

51
Q

Why can general debilitation in hospitalised patients lead to oral candidosis?

A

Increases colonisation and risk of oral disease

52
Q

What is candida vulvovaginitis?

A

Candidiasis in the vagina –> vaginal yeast infection

53
Q

Typical presentation of candida vulvovaginitis?

A
  • Pruritis, burning sensation, +/- discharge
  • Inflammation of vaginal epithelium, may extend to labia majora
  • Often more florid infections during pregnancy
  • Often recurring
54
Q

Treatment of superficial candidosis?

A
  • Usually oral azoles –> fluconazole highly effective
  • Resistance in normally sensitive species (e.g. Candida albicans) or naturally resistant species (Candida krusei) can be problem
55
Q

Why should you NOT use oral fluconazole or other azoles in pregnant women? What should you use instead?

A

this increases risk of teratologies (e.g. heart defects), use topical azoles eg clotrimazole

56
Q

Candida can infect almost any organ in the body. How is it defined?

A

Usually by site of infection

57
Q

How is systemic candidosis usually acquired?

A

From colonised skin or mucosal sites, or from GI tract (usually seem in the compromised host)

58
Q

Which is the most common species of Candida?

A

Candida albicans

59
Q

What is candida oesophagitis? Who is it seen in?

A
  • Candidiasis in the oesophagus
  • Mainly in HIV
  • In 10-20% patients with oropharyngeal disease
  • Pain/difficulty on eating/swallowing
  • Diagnosed by endoscopy with biopsy
60
Q

What is candidaemia? How should it be treated?

A
  • Presence of candida in blood culture
  • Start antifungal therapy
  • Remove lines (where possible)
  • Check eyes and heart
    • For endocarditis and endophthalmitis
61
Q

Candidaemia can lead to occular candidosis. What are the 2 forms of this?

A

Candida chorioentinitis and endophthalmitis

62
Q

What is candida endocarditis? Who is it seen in?

A
  • A rare consequence of candidaemia
  • IV drug users
  • Valve surgery –> vegetations seen on heart valves
63
Q

Typical presentation of candida endocarditis?

A

Fever, weight loss, fatigue, heart murmur

64
Q

How are urinary tract Candida infections caused?

A

Ascending from genital tract infection/colonisation or from catheterisation

65
Q

Who are urinary tract Candida infections more common in?

A

Women, diabetics, damaged/abnormal urinary tracts, ICU patients

66
Q

What is candida peritonitis?

A
  • Complication of peritoneal dialysis
  • Can be caused by perforation of bowl during surgery
  • Fever, abdominal pain, nausea, vomiting
67
Q

Treatment of systemic candidosis?

A

–Depends on Candida sp. sensitivity, severity, need for oral agent

–Echinocandins, e.g. Anidulafungin (IV)

–Azoles, e.g. Fluconazole (oral)

–Liposomal Amphotericin B (IV)

68
Q

Aspergillus:

  • yeast or mould?
  • common form of exposure?
A
  • Genus of moulds - filamentous fungi producing airborne spores
  • Exposure to Aspergillus spores universal by inhalation
  • Airways may be colonised by Aspergillus sp. (doesn’t always mean infection)
69
Q

What are 4 medically important species of Aspergillus?

A

–Aspergillus fumigatus (most common)

–Aspergillus niger

–Aspergillus flavus

–Aspergillus terreus

70
Q

What is aspergillosis?

A
  • Reaction to inhaled Aspergillus
  • Infection usually affect the respiratory system
71
Q

In cavities (e.g. lungs), what can aspergillus cause?

A

An aspergilloma is a clump of mold which exists in a body cavity such as a paranasal sinus or an organ such as the lung. By definition, it is caused by fungi of the genus Aspergillus.

72
Q

In patients with asthma or CF, what can aspergillus cause?

A

Allergic reaction:

  • Allergic bronchopulmonary aspergillosis
  • allergic sinus disease
73
Q

Aspergillosis can become a chronic infection. What lung disease can this cause?

A

Chronic pulmonary aspergillosis

74
Q

Aspergillosis can lead to an invasive infections especially in immunocompromised patients. What can this lead to?

A

Invasive pulmonary aspergillosis, invasive aspergillus sinusitis

75
Q

Which patients can develop cavities in their lungs which can, in turn, lead to aspergilloma?

A

Patients with cavities from previous tuberculosis, sarcoid, surgery

76
Q

Aspergillomas are often indolent, but what can they cause if they break up?

A

Haemoptysis and are potentially fatal

77
Q

What is the most common form of allergic aspergillosis?

A

Allergic Bronchopulmonary aspergillosis

78
Q

How does allergic Bronchopulmonary aspergillosis typically present? How is IgE affected?

A
  • Wheezing
  • breathlessness
  • loss of lung function
  • bronchiectasis
  • Airways inflammation

Raised total IgE

Specific IgE and G reaction to Aspergillus

79
Q

How is allergic Bronchopulmonary aspergillosis treated?

A

Responds to steroids, sometimes antifungal therapy added

80
Q

Who is most prone to developing chronic pulmonary aspergillosis?

A

Patients with COPD

81
Q

How does chronic pulmonary aspergillosis typically present?

A

Chronic respiratory symptoms, cough, wheezing, breathlessness, chest pain

82
Q

Who is invasive aspergillosis most commonly seen in?

A

Patients with haematological malignancy, stem cell and solid organ transplant –> low neutrophil counts

83
Q

How does invasive aspergillosis spread?

A
  • Angioinvasion of lung tissue
  • Dissemination in c. 25% of cases to extrapulmonary sites
84
Q

What is present in chest CT of invasive aspergillosis?

A

Halo and air crescent signs on chest CT

85
Q

What is the prognosis for invasive aspergillosis?

A

Moderate to poor prognosis, even with aggressive antifungal therapy

86
Q

Treatment for aspergilloma?

A

Resection

87
Q

Treatment for allergic aspergillosis?

A

Steroids +/- antifungals

88
Q

Treatment for chronic pulmonary aspergillosis and invasive aspergillosis?

A

Antifungals; itraconazole, amphotercin B

89
Q

What does this picture show?

A

Pityriasis versicolor –> characteristic small round yeast cells combined with short sections of hyphae (grapes + bananas)

90
Q

This is an aspergilloma (cavity filled with fungal ball). What is most likely to have formed the original cavity?

A

tuberculosis

91
Q

Who is most likely to present with tinea capitis?

A

Prepubescent children

92
Q

Which kinds of patients present with this form of oral candidosis? What is this form?

A
  • Erythematous form
  • Mainly seen in older patients
93
Q

Which is the best antifungal for urinary tract candidosis?

a) itraconazole
b) terbinafine
c) fluconazole
d) caspofungin
e) voriconazole

A

Fluconazole

94
Q

5 yr old male, background of CF, raised total IgE, Aspergillus specific IgE and IgG, mucous plugging in lungs, wheeze.

Diagnosis?

A

Allergic bronchopulmonary aspergillosis

95
Q

In what context is the following sign seen?

A

Candidaemia –> can lead to occular candidosis

96
Q

Where might this tinea cruris lesion have spread from?

A

Feet - tinea pedis

97
Q

Name this fungus

A

Aspergillus fumigatus (the spores shedding off the head are what we inhale)

CP reviewer 1 (59 decks)

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