Microreview102A(Systemic Mycoses)

Front 1

Name the four endemic fungi considered to cause systemic infections in humans?

Back 1

Histoplasma,Coccidioides, Blastomyces, Paracoccidioides

Front 2

Are all systemic fungi dimorphic?

Back 2

Yes. They can exist as either yeast or mold forms.

Front 3

In what form do they appear at body temperature?

Back 3

Around body temperature(37C), they grow as yeast forms on blood agar. At 25C they grow as mold forms with spores on Sabouroud's agar.

Front 4

How do systemic fungi enter the body?

Back 4

Through the inhalation of fungal spores.

Front 5

Is there person to prson spread of these diseases?

Back 5

No. Only spores are infective and must be inhaled directly from soil or bird droppings.

Front 6

Describe three types of infection that systemic mycoses are known to cause?

Back 6

Asymptomatic/mild upper respiratory infection(URI), majority odf cases.
Pneumonia: A mild pneumonia with fever, cough, and infiltrates seen on X-ray. Note that infections with these organisms can be caused calcified granulomas.
Disseminated: Rare, usually in immunocompromised patients. The fungus spreads hematogenously from the lungs causing granulomatous infections throughout the body.

Front 7

Which one of the above four fungi is a facultative intracellular parasite known to infect reticuloendothelial cells?

Back 7

Histoplasma capsulatum.

Front 8

Histoplasma is often seen as oval budding yeast inside macrophages.What substances do the yeast produce which allows it to survive in the harsh environment of the phagolysosome?

Back 8

The yeast produces alkaline substances such as bicarbonate and ammonia, which raise the pH of the phagolysosome thereby inactivating the degradative enzymes.

Front 9

What areas of the country is Histoplasma endemic?

Back 9

Eastern great lakes, Ohio, Mississippi, and Missouri river valleys.

Front 10

Histoplasmosis is most common in the summer. TRUE/FALSE

Back 10

TRUE.

Front 11

What animals are associated with Histoplasma infections?

Back 11

It is found in soil contaminated with bird or bat feces.

Front 12

What activities put one at increased risk of contracting the disease?

Back 12

Any activities that expose one to bird and bat feces, including spelunking, cleaning chicken coops or bulldozing starling roosts.

Front 13

Why is it useful to obtain peripheral blood smears in patients suspected with Histoplasma infection?

Back 13

It circulates in the RES(reticulo-endothelial system) cells, it can be seen in peripheral smears.

Front 14

Describe the tissue form of the disease.

Back 14

Small intracellular yeasts, which despite their name are not encapsulated.

Front 15

In a patient with suspected Histoplamosis, what abbnormally might be found on physical exam of the abdomen?

Back 15

Hepatosplenomegaly. Since H. infects reticuloendothelial cells.

Front 16

In patients from the endemic area, what radiographic findings suggest prior infection with H?

Back 16

Calcified granulomas in the spleen and lungs.

Front 17

Name the systemic fungus that is endemic in the south western US whose environmental form resembles hyphae breaking up intoarthroconidia found in desert sand.

Back 17

Coccidioides immitis(valley fire).

Front 18

Describe the morphology of the tissue form of Coccidioides infection?

Back 18

Spherules with endospores.

Front 19

What skin rash is associated with Coccidioides infection?

Back 19

Erythema nodosum. It is a skin disease characterized by tender red nodules found beneath the skin, usually on the shins, as well as fever, and joint pain. In cases of Coccidioides infections, it serves as a positive prognostic indicator suggesting an active cell mediated immune response to the organism.

Front 20

Why is Coccidioides infection a concern in pregnant patients?

Back 20

It has a tendency to disseminate in the 3rd trimester of pregnancy.

Front 21

What is the most important extrapulmonary site of dissemination?

Back 21

Meninges

Front 22

Describe the impact of race on the natural history of Coccidioidomycoses.

Back 22

Non-Caucasians have a higher rate of disseminated infection.

Front 23

Name the systemic funguswhose tissue form resembles broad based budding yeast?

Back 23

Blastomyces dermatitidis

Front 24

Which opportunistic fungus forms narrow based budding yeast?

Back 24

Cryptococcus neoformans

Front 25

What is the endemic region associated with Blastomyces?

Back 25

The fungus is found in the Great Lakes region, the Ohio and Mississippi river valley as well as the northeastern US extending into Canada.

Front 26

What is the environmental form of Blastomyces?

Back 26

Hyphae with Conidia.

Front 27

Whereas acute lesions with Histoplasma and Coccidioides often spontaneously resolve, Blastomyces infections are often treated with either of what medication?

Back 27

Itraconazole. Amphoteracin B may be used in severe disseminated cases.

Front 28

Name the serious side effects of Amphoteracin B that may limit its use in the clinical setting.

Back 28

Renal toxicity(which is reversible) fevers and chills, anemia and phlebitis at the IV site.

Front 29

Which systemic fungus is endemic in rural Latin America?

Back 29

Paracoccidioides brasiliensis, also known as South American blastomycosis, is found in the soil.

This yeast is thick walled with multiple buds, escribed as the captain's wheel.

Front 30

What bacterial infection may mimic systemic mycotic infection?

Back 30

M. tuberculosis can resemble systemic mycoses, as both are acquired through the respiratory route and cause asymptomatic to chronic lung infections, leaving granuloma's, calcifications and possibly cavitary lesions. Also, both can spread hematogenously, infecting distant body organs.