w20 superficial ,cutaneous & subC fungi Flashcards
1
Q
LO
A
Classify different pathogens that can cause superficial, cutaneous and subcutaneous infection
Knowledge of disease symptoms of each
Understand diagnosis methods
Aware of different treatment options
Extra reading:
Murray’s Medical Microbiology book Chapter 62 and 63
2
Q
What is a true pathogen vs opportunistic
A
fungal Ps can cause disease in anyone vs opportunistic fungal Ps that only can infect immunocomp
3
Q
What type of fungi affects the superficial cutaneous areas of the skin and scales etc.
A
superficial fungi
4
Q
Where are the cutaneous areas
A
skin hair nail
5
Q
where are the subcutaneous zones in the body
A
lymphatic system & internal layers of skin (dermis)
6
Q
Name 2 superficial cutaneous mycoses
A
Tinea versicolor
Tinea nigra
7
Q
What infectious agent causes Tinea Versicolor
A
Malassezia furfur
8
Q
Wha causes Tinea Nigra
A
Hortaea werneckii
9
Q
Who identified Malassezia in late 1900s
A
Louis-Charles Malassez , french
10
Q
Yeast form, basiidiomycota
A
Tinea versicolor
11
Q
Describe the epidemiology of Tinea versicolor
A
^ prevalent in tropical & subtrop. regions (may affect up to 60% population in tropics)
Common in summer
Animals not affected
Is not found as saprophyte in nature
Transmission by direct or indirect transfer of infected keratinous material from one person to another
12
Q
Clinical syndromes of Tinea Versicolor involes….
A
hypo or hyperpigmented macules inv. upper trunk, arms,chest,shoulders,face.mask
13
Q
What do lesions look like in Timea Versicolor ?
A
irregular, well demarcated pathches of discoloration raised and covered by scale sometimes
14
Q
Lesions are ____________ but may involve hair follicles
A
asymptomatic
15
Q
hair folllicles inv. w lesions in Tunea.v can lead to
A
folliculitis, perifolliculitis and rarely dermal abscess.
16
Q
Black yeast/fungus/dematiaceous fungus prdouce _______ in walls
A
Tinea Nigra ; prod. melanin in their walls (black fungus, yeast, dematiceous fungi)
; appears as irregular,solitary pigmented macule on palms or soles without scaling or invasion
17
Q
Is TNigra contagious
A
no & lesion grossly resembles malignant melanoma
17
Q
What does black fungus Hortaea wernickii look like (use form key term)
A
branched hyphae , Ascomycota
18
Q
What type of environment is Tinea Nigra more prevalent in
A
tropical & subtropical areas
19
Q
How can Tinea Nigra be contracted
A
likely contraction by traumatic inoculation of fungus into epidermal superficial layers (img is red dotty hands )
20
Q
Describe the fungal morphology of TNigra under a microscope
A
dark pigmented, frequently branched
SEPTATE HYPHAE & 2-celled yeastlike cells
21
Q
How is the TN sampled for analysis i.e via microscopy
A
using skin scrapings (mounted in 10% KOH)
22
Q
In culture at 25 degrees what can be observed at one week (Tinea Nigra)
A
Black colonies contain. yeast like (2 celled) annelioconidia
23
Q
what is annelioconidia
A
conidia with rings
24
After 2/3 weeks in culture Tinea Nigra, what can be observed
mycelial forms of TN found ; devpmt from 1 week annelloconidia
25
How is Tinea Nigra treated
topical treatments ; azole creams i.e 2% miconazole cream et.c
26
How many major species of fungi can cause cutaneous mycoses
3
27
Name the 3 major fungi species that can cause cutaneous mycoses
Trichophyton ; Microsporum ; Epidermophyton
(Ascomycota phylum) - how related ?
28
Trichophyton is a fungi that causes cutaneous mycoses in which cutaneous areas
skin hair and nails
29
Which major fungi species causes cutaneous mycoses in the skin and nails
epidermophyton
30
Microsporum is a major fungi species that causes CMycoses in which cutaneous areas
skin and hair
31
What structures are affected by cutaneous mycoses and is it threatening
inv. keratin containing structures & moist area; dont invade subcutaneous tissues
not life threatening
virulence of fungi = low
32
What 2 forms can be observed in cutaneous mycoses
conidial forms and mycelial
33
What are the three major species that cause cutaneous mycoses collectively referred to
dermatophytes , tinea or ringworm
34
What are the types of classification of dermatophytes classified
classified as anthropophilic (humans), zoophilic or geophilic according to normal habitat
35
What is Tinea Capitis
disease of scalp, eye browns and eye lashes ; cutaneous mycoses
36
Name types of other tinea and where they affect
Tcorporis - skin
T.FACIALIS - trichophyton rubrum (granules) ; mentagrophytes or gypseum
37
Onychomycosis is disease of the
nails i.e Tinea Ungium or T.rubrum
38
What can the skin scales, hair and nails be used for in terms of diagnosing c.mycoses
clinical signs & symptoms, microscopic examination of tissue
39
How are specimens prepped for microscopic exam for Cmycoses
placed on slide w drop of 10% potassium hydroxide (KOH) after 10-15 mins examined for hyphae and conidia
40
Name the 3 different morphology of condiophores used for diagnosis (describe if remember imgs)
microsporum: macroconidia
; trichophyton: microconidia , few or no macroconidia
Epidermorphyton: macroconidia in clusters of 2/3
41
What can endothrix & ectothrix infections be distinguished by in microscopic examination
Endothrix : invasion & internalisation into hair cells
Ectothrix: hyphae seen SURROUNDING hair shaft
42
What technique is used to identify colonies in hair infection
Cultures on sabouraud agar: identfied by microscopic morphology of conidia and hyphae
43
Topical creams typically treat which cutaneous mycoses and what do the creams contain
superficial mycoses - azoles (suffix too)
44
Refractory cutaneous mycoses infections require oral Griseofulvin or Itraconazole or fluconazole
45
Nail infection is treated with
oral therapy w Terbinafine or Griseofulvin
46
Global Prevalence of fungal skin infections is ...
500 million
47
Candida glabrata is a common pathogen of newborns (T/F?)
false
48
Echinocandins inhibit which pathway
GLUCAN BIOSYNTHESIS PATH
49
Name 4 known C.albicans-macrophage interactions
KILLING
Non-lytic expulsion
Escape
Pyroptosis
50
What is one form C.albicans CANNOT form
Vacoule
51
STILL NEED TO DO SUBCUTANEOUS SLIDES..
52
Lymphocutaneous sporotrichosis IS CAUSED BY WHAT
Sporothrix schenckii
53
Chromoblastomycosis caused by dematiaceous fungi , Name some examples of DF
Fonsacaea, Cladosporium, Exophila, Cladophialophora and Phialophora
54
Eumycotic mycetoma is caused by what fungi
Medurella grisea and Actinomadura medurae
55
Name 3 types of SUBcutaneous mycoses
Eumycotic mycetoma
Chromoblastomycosis
Lymphocutaneous sporotrichosis
56
Describe sporothrix schenckii which causes lymphocutaneous sporotrichosis
(Ascomycota), a dimorphic fungus ubiquitous in soil and decaying vegetation
57
In what form of sporothrix schenckii is the condidia arranged like daisies
mycelial (pink stained img)
58
Lymphocutaneous sporotrichosis ;Epidemiology
sporadic ^ common in warmer climates;
200-250 cases in USA/year, incidence not well reported; cases in Peru, Brazil, China, South Africa, Australia
59
Etiology of lymphocutaneous sporotrichosis
Sporothrix schenckii
60
Why is Lymphocutaneous sporotrichosis referred to as rose-growers disease and how does it relate to disease development
Entry: after local trauma, often observed in gardeners and may develop via a thorn prick (rose-growers' disease)
Pricking of a finger, a pustule develops and ulcerates; the infection invades the lymphatic system and ascends the arm, resulting in a chain of subcutaneous nodules that later ulcerate and discharge pus
61
Pathology of Lymphocutaneous sporotrichosis
Primary lesion: appears in 1-10 weeks
chronic inflammation of lymph vessel and lymph nodes: granulomas
62
Lymphocutaneous sporotrichosis
Diagnosis: direct microscopy is usually negative,
Asteriod bodies (yeast surrounded by amorphus material) in histopathological sections. A confirmed diagnosis is made on culture
63
How can Lymphocutaneous sporotrichosis be treated
Treatment: KI (potassium iodide) over 3-4 weeks;
side effects include nausea, salivary gland enlargement;
itraconazole is also the drug of choice
Good prognosis
64
Describe the clinical manifestation presented bya Classic lymphocutaneous form of sporotrichosis
chain of subcutaneous nodules along the lymphatic
drainage of the arm
65
sporotrichosis causes what in the face
localised skin lesions i.e around eyes and nose ; red, scabby or bumpy
Hand and fingers are most commonly involved
66
Chromoblastomycosis or chromomycosis is caused by what type of fungi
Caused by inoculation of pigmented (dematiaceous) fungi (Fonsacaea, Cladophialophora and Phialophora)
67
How does dematiacous fungi affect the skin and subcutaenous tissues in chromoblastomycosis
characterised by development of slow growing verrucous nodules or plaques
68
epidemiology of chromoblastomycosis
Common in tropics due to lack of protective footwear involving legs and arms in men; non-contagious
69
Sclerotic body
Medlar bodies
Muriform cells
type of bodies that form on plaques from trauma assoc. w chromoblastomycosis ; can be observed in direct examination
70
Chromoblastomycosis: Clinical manifestations of early stages
Early lesions are small warty papules that enlarge slowly (late diagnosis ~ 10 years)
71
Chromoblastomycosis: Clinical manifestations of established infection
Established infections appear as multiple large warty cauliflower-like growths that are usually clustered within the same region involving ulceration and cyst formation
Limbs get grossly distorted due to fibrosis (excess of fibrous tissue) and lymphoedema (retention of liquid)
72
Secondary bacterial infections OF WHAT SUBCUTANEOUS MYCOSES CONDITION may lead to eventual elephantiasis (important swelling of limbs)
Chromoblastomycosis (fat warts covering whole limb thats red and cauliflower like)
73
What can be seen in microscopic examination of chromoblastomycosis
Brown pigmented spherical fungal elements (i.e., sclerotic, or “copper penny” bodies) with transverse and horizontal septa are found in scrapings treated with KOH and in histopathologic preparations.
74
What is seen in culture examination of chromoblastomycosis
A confirmed diagnosis is made by culture (olive black colony) and identification of the etiologic agent but the formation of characteristic conidial structures may require weeks to months of incubation.
75
Treatment for chromoblastomycosis
Treatment is usually ineffective due to advanced stage of infection at the time of presentation - chronic cases resistant to trmt
Itraconazole and terbinafine are most effective, if at all. These drugs can be combined with flucytosine in refractory cases
Surgical amputation in advance cases
Chromoblastomycosis remains one of the most difficult deep mycotic infection to eradicate
76
Eumycetoma / Madura foot
Mycetoma appear as a localised abscess that discharge pus, serum
and blood through sinus (abnormal channel).
subcutaneous mycoses that bumpy skin like filled vesicles under which then bleed and drain at later stages of infection
77
One difference between eumycetoma and chromoblastomycosis
resembles chromoblastomycosis but usually lacks the large wart – like lesions.
78
Etiology of eumycetoma
caused by a variety of fungi. Most common causative agents are Medurella grisea and Actinomadura medurae in temperate climates.
79
Pathogenesis & Clinical Manifestations of Eumycetoma
Mycetoma typically begins in a wound or abrasion contaminated with soil. It may start in the form of painless nodule.
Feet and legs are the most common sites of infection, although other parts of the body may be involved. Secondary bacterial infections may also occur.
The disease is characterised by chronic granulomatous inflammation, and the formation of draining sinus tracts is common. The abscess from the sinus contain large aggregates of fungal hyphae (granules: 0.2-5mm)
80
Epidemiology of Eumycetoma
Tropics with low rainfall;
Africa and Indian subcontinent, but also seen in Brazil, Venezuela, and the Middle East;
mostly men affected;
non-contagious
disease develops quick after trauma i.e large mass dvpd 2 months after ankle abrasion
81
What type of biopsy is needed to diagnose eumycetoma
skin biopsy
82
How is eumycetoma diagnosed using a microscope
specimen treated with potassium hydroxide (KOH) confirms the diagnosis. Fungal grains contain short hyphae.
83
Diagnosis of eumycetoma requires distinguishing between grains in...
depends on identifying coloured grains (black and white grains) in pus and discharge.
84
CuLTURE OF EUMYCETOMA
Culture: Several agar plates are cultured at 25 and 37oC for up to 6 weeks.
85
Most successful treatment for eumycetoma is
amputation
usually unsuccessful, some response to AmB, itraconazole, ketoconazole, terbinafine;
86
Which of the following is not a feature commonly associated with Eumycetoma ?
1 - Draining Sinuses
2- Cauliflower like growths
3 - Chronic Granulomatous Inflammation
4 - Discharge containing large aggregates of fungal hyphae
87
Sporothrix schenckii targets the
Gastrointestinal tract
Central Nervous system
Lymph system
Circulatory system
lymph system ; revise related lymph content make few cards
88
Azoles typically target the
Ergosterol in the fungal membrane
Cholesterol in the fungal membrane
Ergosterol synthesis enzymes
Cholesterol synthesis enzymes
Ergosterol synthesis enzymes
89
Hortaea werneckii is the etiological agent for
1 -Chromoblastomycosis
2- Tinea Nigra
3- Tinea versicolor
4- Eumycetoma
Tinea Nigra
90
By Inhibiting ergosterol synthesis, azoles antifungal mechanism works as
inability to produce ergosterol increases the membrane's permeability, which results in cell lysis and death
91
Name the 4 types of TRUE (primary) pathogens
Superficial
Cutaneous
Subcutaneous
Systemic
