Microbiology:Mycology

Question 1

What is the exception to the rule that all systemic mycoses are dimorphic with mold at cold temperatures and yeast at high temperatures?

Answer 1

Coccidiomycoses which form a spherule in tissue

Question 2

What is the treatment for local infections of systemic mycosis? Systemic?

Answer 2

Fluconazole or itraconazole

Amphotericin B

Question 3

What mycoses is found in the Mississipi and Ohio river valleys and causes pneumonia?
What is it transmitted by?

Answer 3

Histoplasmosis

Bird of bat droppings

Question 4

What will be seen microscopically when looking for Histopoasmosis?

Answer 4

Small yeast in MACROPHAGES (smaller than RBC)

Question 5

What mycoses will be seen east of the Mississippi river and in Central America, and causes inflammatory lung disease which can disseminate to the skin and bone along with granulomatous nodules?

Answer 5

Blastomyosis

Question 6

What will be seen on microscopy when looking at Blastomycosis?

Answer 6

Large, broad-base budding yeast (larger than RBC)

Question 7

What mycosis is seen in the SW US and California, causes pneumonia and meningitis, and can disseminate to the bone and skin?

Answer 7

Coccidioidomycosis

Question 8

What is seen on microscopy when looking at Coccidioidomycosis?

Answer 8

Spherule filled with endospores

Question 9

Where is paracoccidioidomycosis seen? What is seen on microscopy?

Answer 9

Latin America

Budding yeast with captain’s wheel formation (larger than RBC)

Question 10

What causes Tinea versicolor?

Answer 10

Malassezia furfur (hot, humid weather)

Question 11

What causes the hypo pigmented patches in Tinea versicolor?

Answer 11

Degradation of lipids producing acids that damage melanocytes

Question 12

Treatment of tinea versicolor?

Answer 12

Topical miconasole and selenium sulfide

Question 13

Appearance of Malassezia furfur on microscopy

Answer 13

Spaghetti and meatball appearance

Question 14

Location of:
Tinea pedis
Tinea cruris
Tinea corporis
Tinea capitus
Tinea unguium

Answer 14

Tinea pedis: foot
Tinea cruris: groin
Tinea corporis: body
Tinea capitus: head and scalp
Tinea unguium: nails

Question 15

Presentation of tinea pedis, cruris, etc

What causes these tineae?

Answer 15

Pruritic lesions with central clearing (ring)

Dermatophytes (Microporum, Trichophyton, Epidermophyton)

Question 16

What will be seen on KOH prep with dermatophyte infection?

Answer 16

Mold hyphae (not dimorphic)

Question 17

Candida infection in immunocompromised (neonates, steroids, diabetes, AIDS)?

Answer 17

Oral and esophageal thrush

Question 18

Candida infection seen in diabetics and post-antibiotic use?

Answer 18

Vulvovaginitis

Question 19

What kind of candida infection can IV drug users get?

Answer 19

Endocarditis

Question 20

What kind of candida infection does a low T cell lead to? Neutropenia?

Answer 20

Low T cell: localized infection

Low PMN: hematogenously disseminated disease

Question 21

Tx of different kinds of candida infections:

• Vaginal
• Oral/esophageal
• Systemic

Answer 21

• Vaginal: topical azole
• Oral/esophageal: fluconazole or caspofungin
• Systemic: fluconazole, amphotericin B, caspofungin

Question 22

Who is more prone to getting invasive aspergillosis?

Answer 22

Immunocompromised

Chronic Granulomatous Disease

Question 23

Where are aspergillomas most likely to occur?

Answer 23

In lung cavities after TB infection

Question 24

How are some species of Aspergillus associated with hepatocellular carcinoma?

Answer 24

Produce aflatoxins

Question 25

What fungi have hyphae that grow at 45 degree angles? Wide angles?

Answer 25

Acute angles: Aspergillosis | Wide angles: Mucor and Rhizopus

Question 26

What fungus causes "soap bubble lesions" in the brain?

Answer 26

Cryptococcus neoformans

Question 27

Where is cryptococcus neoformans found in the environment?

Answer 27

Soil and pidgeon droppings - acquired through inhalation with hematogenous dissemination to the meninges

Question 28

What fungus causes headache, facial pain, and black necrotic eschar on the face in ketoacidotic diabetic and leukemic patients?

Answer 28

Mucor and Rhizopus

Question 29

Mucor and rhizopus proliferates in blood vessel walls when there is excess:

Answer 29

Glucose and ketone | penetrates the cribriform plate and enters the brain

Question 30

What kind of lesion does nucor and rhizopus cause in the brain?

Answer 30

Rhinocerebral frontal lobe abscesses

Question 31

What prophylaxis is given to AIDS patients whose CD4 counts drop below 200 cells/mm3? What is it for?

Answer 31

TMP-SMX (or pentamidine, dapsone) | Pneumocystis jirovecii

Question 32

What does infection with pneumocystis jirovecii cause?

Answer 32

Pneumocystic pneumonia (PCP), a diffuse interstitial pneumonia

Question 33

What will be seen on silver stain of lung tissue with a P. jirovecii infection?

Answer 33

Disc-shaped yeast

Question 34

What is a dimorphic, cigar shaped budding yeast that lives on vegetation?

Answer 34

Sporothrix schenckii?

Question 35

How does Sporothrix schenckii infection typically occur?

Answer 35

Traumatic introduction of spores into skin (usually by a thorn, "rose gardener's disease")

Question 36

What does Sporothrix schenckii infection cause?

Answer 36

Local pustule Ulcer with nodules along draining lymphatics (ascending lymphangitis) **rarely causes systemic illness

Question 37

Tx for Sporothrix schenckii infection?

Answer 37

Itraconazole or potassium iodine | plant a rose in a POT