FA - Micro - Mycology Flashcards Preview

Microbiology > FA - Micro - Mycology > Flashcards

Flashcards in FA - Micro - Mycology Deck (62):
0

3 features about systemic mycoses?

1. ALL can cause pneumonia
2. Can disseminate
3. ALL caused by dimorphic fungi: cold (20C)=mold, heat(37C)=yeast.
Only exception: Coccidioidomycosis - spherule (not yeast) in tissue.

1

Treatment for systemic mycosis?

1. Fluconazole (local infection)
2. Itraconazole (local infection)
3. Amphotericin B (systemic infection)

2

Systemic mycosis can mimic what?

TB (granuloma formation), EXCEPT, unlike TB, have no person-person transmission.

3

Histoplasmosis - Endemic location?

Mississippi and Ohio river valleys.

4

Histoplasmosis cause?

Pneumonia.

5

Histoplasmosis special feature?

Macrophage filled with Histoplasma (smaller than RBC) - Histo Hides (within macros).
BIRDS (eg starlings) and BATS droppings.

6

Blastomycosis - Endemic location?

States east of Mississippi River and Central America.

7

Blastomycosis - cause?

Inflammatory lung disease - can disseminate to skin and bone.
Forms granulomatous nodules.

8

Blastomycosis - Special feature?

Broad-base budding (same as RBC).

9

Coccidioidomycosis - Endemic location?

Southwestern US, California.

10

Coccidioidomycosis - cause?

1. Pneumonia
2. Meningitis
3. Can disseminate to bone and skin.

11

Coccidioidomycosis - Special features?

1. Case rate UP after earthquakes (spores in dust are thrown up in the air and become spherules in the lungs).
2. Spherule (MUCH LARGER than a RBC) filled with endospores.

12

Paracoccidioidomycosis - Endemic location?

Latin America.

13

Paracoccidioidomycosis - Special feature?

Budding yeast with "captain's wheel" formation (MUCH LARGER THAN RBC).

14

Tinea versicolor - Cause?

Malassezia spp. (Pityrosporum spp.) ==> A yeast-like fungus (NOT A DERMATOPHYTE despite being called tinea).

15

Tinea versicolor - Pathogenesis?

Degradation of lipids produces acids that damage MELANOCYTES --> hypopigmented and/or PINK patches.

16

Tinea versicolor - When?

Can occur ANY TIME of year, but more common IN SUMMER ==> Hot, humid weather.

17

Tinea versicolor - treatment?

1. Topical miconazole
2. Selenium sulfide (Selsun)

18

Tinea versicolor - Microscopic morphology?

"Spaghetti and meatball" appearance.

19

Other tineae?

Tinea pedis
Tinea cruris (groin)
Tinea corporis
Tinea capitis
Tinea unguium (onychomycosis, on fingernails)

20

Other tineae - Features?

Pruritic lesions with central clearing resembling a RING.

21

Other tineae - causes?

By dermatophytes - Microsporum, Trichophyton, Epidermophyton.

22

Dermatophytes - Microscopic morphology?

BRANCHING SEPTATE HYPHAE visible on KOH preparation with BLUE FUNGAL STAIN.

23

C.albicans - causes?

1. Oral-esophageal thrush in immunocompromised (Neonates+ Steroids + Diabetics + AIDS).
2. Vulvovaginitis (diabetes, use of antibiotics).
3. Diaper rash
4. Endocarditis in IVDA
5. Disseminated candidiasis (any organ)
6. Chronic mucocutaneous candidiasis

24

C.albicans - Treatment?

Vaginal --> Topical azole.
Oral/esophageal --> Nystatin, fluconazole, or caspofungin.
Systemic --> Fluconazole, ampho B, caspofungin.

25

C.albicans - dimorphic?

YES:
1. Pseudohyphae and budding yeasts at 20C.
2. Germ tubes at 37C.

26

Aspergillus fumigatus - causes?

1. Invasive aspergillosis
2. Allergic bronchopulmonary aspergillosis (ABPA)
3. Aspergillomas in lung cavities (especially after TB)
4. Some produce aflatoxins --> HCC.

27

Invasive aspergillosis - features?

1. In immunocompromised
2. In Chronic granulomatous disease

28

Allergic bronchopulmonary aspergillosis - features?

1. Asthma - CF associations.
2. May cause bronchiectasis/eosinophilia.

29

A.fimugatus - Dimorphic?

NO - Septate hyphae that branch at 45 degree angle ==> Produces conidia in radiating chains at END of CONIDIOPHORE.

30

C.neoformans - causes?

1. Cryptococcal meningitis.
2. Cryptococcal encephalitis ("soap bubble" lesions in brain), primarily in IMMUNOCOMPROMISED.

31

C.neoformans - Morphology + Capsule?

Heavily encapsulated yeast.
5-10μm with NARROW BUDDING.

32

C.neoformans - Dimorphic?

NO!!!

33

C.neoformans - where?

In soil, PIGEON droppings.

34

C.neoformans - transmission?

Inhalation with hematogenous dissemination to meninges.

35

C.neoformans - Culture?

Sabouraud agar.

36

C.neoformans - Stain?

1. India ink ==> Clear halo.
2. Mucicarmine ==> Red INNER CAPSULE.

37

C.neoformans - diagnostic test?

Latex agglutination test detects polysaccharide capsular antigen and is more specific.

38

Mucormycosis - target group?

1. Ketoacidotic diabetics.
2. NEUTROPENIC patients (Eg leukemia).

39

Mucormycosis - Pathogenesis?

Fungi proliferate in blood vessel WALLS when there is excess ketone and glucose ==> Penetrate cribriform plate ==> Enter brain.

40

Mucormycosis - Features?

1. Rhinocerebral, frontal lobe abscesses.
2. Headache
3. Facial pain
4. Black necrotic eschar on face.
5. May have cranial nerve involvement.
6. CAVERNOUS SINUS THROMBOSIS.

41

Mucormycosis - Treatment?

Surgical debridement + Amphotericin B.

42

Mucor - Microscopy?

Irregular, broad, nonseptate hyphae branching at wide angles.

43

P.jirocevii?

Pneumocystis pneumonia - Diffuse interstitial pneumonia.

44

P.jirovecii - transmission?

Inhaled.

45

P.jirovecii - CXR/CT appearance?

Diffuse, BILATERAL ground-glass opacities on CXR/CT.

46

P.jirovecii - Diagnosis?

Lung biopsy or lavage.

47

P.jirovecii - microscopy?

Disc-shaped yeast forms on METHENAMINE SILVER stain of lung tissue.

48

P.jirovecii - treatment?

1. TMP-SMX
2. Pentamidine
3. Dapsone (proph only)
4. Atovaquone (proph only)

49

P.jirovecii - prophylaxis in AIDS patients?

Start when CD4 count drops <200cells/mm^3 in HIV patients.

50

Sporothrix schenckii - Causes?

Sporotrichosis.

51

Sporothrix schenckii - Morphology?

Dimorphic - CIGAR-SHAPED budding yeast that grows in branching hyphae with rosettes of CONIDIA.
==> Lives on vegetation.

52

Sporothrix schenckii - pathogenesis?

Spores are traumatically intoduced into the skin, typically by a thron (rose gardener's disease) --> Local pustule or ulcer with nodules along draining lymphatics --> Ascending lymphangitis.
Little systemic illness.
==> DISSEMINATED DISEASE possible in IMMUNOCOMPROMISED host.

53

Sporotrichosis - treatment?

Itraconazole or potassium iodide.

54

"(San Joaquin)" Valley fever:

CODDIDIOIDOMYCOSIS.

55

Tinea capitis:

Head + Scalp:
1. Associated with LYMPHADENOPATHY.
2. Alopecia.
3. Scaling.

56

Tinea corporis:

Torso:
==> Erythematous scaling rings ("ringworm") + Central clearing.

57

Tinea corporis can be acquired from contact with ...?

An infected CAT or DOG.

58

Tinea cruris - Occurs in ...?

INGUINAL AREA.

59

Tinea cruris - Often does NOT show ...?

The CENTRAL clearing seen in tinea corporis.

60

Tinea pedis - 3 varieties:

1. Interdigital (MC).
2. Moccasin distribution.
3. Vesicular type.

61

P.jirovecii - Originally classified as ...?

PROTOZOAN. Now, yeast-like FUNGUS.