Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MSII: Microbio Unit 2 > Mycoses (9) > Flashcards

Mycoses (9) Flashcards

1
Q

What are the cutaneous mycoses?

A

Dermatophytoses, Tinea vesicolor, tinea nigara

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What causes dermatophytoses?

A

Dermatophytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do dermatopytes infect?

A

Superficial keratinized structures only!

skin, hair, nails

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the virulence factor of dermatophytes?

A

Keritinase–> allows invasion of the cornified cell layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 major genera of dermatophytes? How are each spread?

A

Epidermophyton (direct contact)

Trichophyton (direct contact)

Microsporum (Direct contact, zoonosis from pets)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe how dermatophytosis presents?

A

Forms chronic infections in warm, humid areas of body surface

Inflammed circular border of papules and or vesicles (skin w/in can be normal)

Broken hairs, thickened/ broken nails

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can be found in some patietns with dermatophytosis that are hypersensitive?

A

They can form “id” reactions–> vesicles on fingers

They are caused by circulating fungal antigen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Do “id” vesicles contain live fungus or spores?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What can happen due to prolonged dermatophytosis?

A

bacterial superinfection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How do you diagnose dermatophytosis?

A

PPD w/ trichophyton

Microskope exam of scraping and KOH mount–> you will see hyphae and spores

Culture on sabouraud’s ager at room temp

Microsporum under wood’s lamp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is dermatophytosis treated?

A

Topical antifungal cream
(**need to treat all affected areas simultaneously)

Oral griseofulvin

Keep skin dry and cool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What causes tinea versicolor?

A

Malassezia furfur or Malessezia globosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Importance of Tinea versicolor?

A

Superficial skin infection only of cosmetic importance. It is an overgrowth of normal flora.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does tinea versicolor present?

A

Hypopigmented areas w/ slightly scaling/ itching

Seen in hot, humid weather

There is also an uncharacterized genetic component (seen in families)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How is tinea versicolor diagnosed?

A

Microscope exam: Skin scraping w/ KOH mount–> you will see yeast and hyphae

Wood lamp will show coppery-orange fluorescence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Treatment of tinea versicolor?

A

Topical selenium sulfide or azole used daily for 2 weeks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What causes tinea nigra?

A

Cladosporium weneckii

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the pathogenesis of tinea nigra?

A

1- spores in soil enter injury
2- Germinate in the keratinized skin layers
3- Generate a brown pigment which appears as a brown spot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Who is tinea nigra mostly seen in?

A

Soutern coastal US and mostly in children.

Overall, it is not common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Diagnosis of tinea nigra?

A

Microscope: skin scraping and KOH mount will show tick septate branching hyphae with dark pigment on their walls

Culture: sabourd’s agaer–> yeast like shiny black colonies grow in 1 week

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Treatment of tinea nigra?

A

Topical keratolytic agen (like salicylic acid)

Topical azole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the subcutaenous mycoses? And how are they contracted?

A

Sporotrichosis
Chromocycosis
Mycetoma

Introduced by trauma exposing subcutaenous tissue to soil or vegitation

23
Q

What causes sporotrichosis?

What is special about the organism?

What is another name for this diease?

A

Sporothrix schenckii

It is thermally dimprophic.

“rose picker’s disease”

24
Q

Pathogenesis of sporotrichosis?

A

Introduced into the skin by thorn puncture.

Yeasts grow at sites and form painless pustule or ulcer.

Draiing lymphatics form suppurating subcutaneous nodules

May progress to disseminated disease and meningitis if immunosuppressed

25
What happens in patients with COPD and those on corticosteroids with a sporotrichosis infection?
They may develop pulmonary symptoms from inhaling the spores (which is difficut to distiguish from TB or histoplasmosis)
26
How is sporotrichosis diagnosed in exam?
Painless pusule/ ulcer (usually on hand or arm) History of gardening History of ineffective antibiotic treatment
27
How is sporotrichosis diagnosed in the lab?
Tissue biopsy--> shows round or cigar-shaped budding yeasts Culture of pus/ biopsy at room temp--> shows hyphae "daisy chains"
28
Treatment of sporotrichosis?
2- months of intraconazole or oral azoles More serious need amphotericin B
29
Where is chromomycosis seen?
Found in soil of the tropics
30
Pathogenesis of chromomycosis?
Introduced into legs or feet with injury by wood splinters or thorns Gradually progressive dubcutaneous disease Granulomas from as immune system attempts to contain the infection Wartlike lesions gradualy spread from initial site
31
What will physical exam show for chromomycosis?
History or travel Wartlike dark colored lesions Crusting abscesses extending along lymphatics
32
How does lab diagnose chromomycosis?
KOH mount shows dark colored septate hyphae or condidia Biopsy shows dark brown, round fungal cells inside leukocytes or giant cells ELISA
33
How is chromomycosis treated?
Oral flucytosine and or itraconazole Local surgery
34
Which two mycosis have dark colored hyphae?
tinea nigra and chromomycosis
35
What causes mycetoma? Where are the organisms found?
Petriellidum or Madurella Found in soil but rare in the US
36
Pathogenesis of mycetoma?
Replicating fungi form abscesses Pus containing compact colored granules forms and drains through the local sinuses Granulomatoous inflammatory response in the deep dermis and subcutaenous tissue may extend to the bone
37
What can mycetoma resemble and how can it be differentiated?
Resembles actinomyces Forms in foot, lower leg or hand, rather than the face actinomyces are smaller and are gram + mycetoma causing fungi are larger and appear in fugal stains
38
How is mycytoma diagnosed?
Needle biopsy for culture H&E stain will show grains in pus X ray to determine whether bone is involved
39
How is mycetoma treated?
First attempt antifungal/ antibiotic therapy Surgical excision of abscess is sometime needed
40
Name a cutaenous and opportunistic mycosis?
Candisiasis
41
Describe candidia?
Yeastlike, oval w/ single bud May also appear as psuedohyphae or hyphae when invading tissues
42
Virulence factors of candidia?
Adhesins for surface attachment Acid proteases and phospholipases for tissue invasion Phenotypic switching/ morphogenesis
43
Symptoms of candidiasis? Common conditions caused by candidia?
Range from trivial superficial to life-threatening systemic. Diaper rash, vaginitis, thrush/ esophagitis
44
Pathogenesis of diaper rash?
dampness from wet diapers predisposing to overgrowth
45
Pathogenesis of vaginitis?
Overgrowth leading to itching and curdlike discharge
46
Pathogenesis of thrush?
Overgrowth leading to psuedomembrane formation in the mouth
47
Who is predisposed to thrush?
Steroid inhaler users HIV + patients not on HAART
48
Name some less common presentations of candidasis?
Skin--> overgrowth becomes red and wet, may be seen on fingers in dishwasers, butt of infants, nail beds in diabetics Folliculitis--> forms a boil Chronic mucocutanous candidiasis--> seen in people with impaired CMI GI infection--> may occur with leukemia/ lymphoma
49
T/F: systemic and disseminated infections of cancidiasis is rare
Once true, but they are now increasing
50
Pathogenesis of systemic candidiasis (candidemia)?
Usually nosocomial with underlying major illness Fever unresponsive to broad-spetrum antibiotics History of cathetarization Endocarditis is seen, also symtoms on skin or moth 30-40% mortality
51
Pathogenesis of disseminated candidiasis (w/ organ invasion)?
One or more deep organs infected (eye, kidney, CNS, joints, muscles, heart/ pericardium, peritonium, spleen) Blood cultures are often negative Fever unresponsive to broad-spectrum antibiotics Mortality is very high
52
How does the lab make the diagnosis of candidiasis?
Exudates and biopsies show: Mix of budding yeasts, psuedohyphae, and hyphae. Gram positive. Visualized by KOH smear, calcoflour white and methylene blue stain Cultures show: Colonies are large Bloodwork: will sometimes be positive for disseminated infection
53
Can candidia develop drug resistance?
Yes, antifungal resistance is common
54
How are candida infections treated?
Treatment ramps up with severity: Topical azoles and polyenes for superficial Oral azoles for more serious but not life threatening Add amphoteracin B for more life threatening Add echinocandins and/ or voriconazole for life threatening drug resistant

MSII: Microbio Unit 2 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions