CHAPTER 32 PRE-LEC
Amphotericin B is an antifungal medication. What might its mechanism of action be?
c. It binds to ergosterol.
Visceral leishmaniasis is __________.
caused by Leishmania donovani
Which of the following is an example of a secondary systemic mycosis?
cryptococcosis that develops in the lungs of a patient with HIV/AIDS
The visceral parasites that are of great concern to people with compromised immune systems include __________.
Cryptosporidium
What is the treatment that Dr. Clark will most likely recommend?
Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host.
Which of the following organisms is most likely the causative agent of Michael's tapeworm infection?
Taenia solium
Compare the anatomy of the tapeworm (Image C) to the anatomy of the roundworm (Image D). Given that both are parasitic worms, which of the following reasons best explains why the tapeworm is flat?
Tapeworms utilize diffusion to absorb nutrients from the host's digestive system.
The human parasitic infection caused by a protozoan that enters through the nose is caused by __________.
d. Naegleria fowleri
Which of the following choices matches a hemoflagellate to its proper insect vector?
d. Trypanosoma cruzi: kissing bug
Fungi that can grow in a yeast or a mold form depending on the conditions are termed __________.
dimorphic
How do pseudohyphae in yeasts differ from vegetative hyphae in filamentous fungi?
Yeasts use pseudohyphae to invade host tissue, whereas filamentous fungi use their vegetative hyphae for obtaining nutrients.
Malaria is caused by a protist that is transmitted by mosquitoes. During its life cycle, the protist goes through cycles of destroying erythrocytes. Which of the following medical consequences is most directly related to this cell damage?
a. anemia
You are examining a sample to determine whether there is a pathogen present that might explain symptoms in a patient. You find a unicellular organism that lacks mitochondria, having mitosomes instead. It has a flagellum and a nucleus. What is it?
b. It must be a eukaryotic protist because it has a nucleus.
What is the correct sequence of events for the life cycle of the pork tapeworm, T. solium?
1. eggs are produced by adult tapeworms living in the definitive host 2. eggs are released to the environment in the feces 3. pigs eat grass contaminated, or fertilized, with human feces. 4. inside the intermediate host, the eggs mature into larvae and encyst in the hosts muscles 5. the definitive host ingests the eggs and becomes infected
Why does Dr. Clark request stool samples for examination?
A. He will have the laboratory prepare the samples for an ova and parasite (O&P) exam. Fresh or preserved stool samples can be observed microscopically for the presence of parasites or their eggs/cysts. B. Tapeworms are pathogens of the gastrointestinal tract; as a natural progression of digestion some of the tapeworm pieces will be expelled along with fecal matter.
Why was Dr. Clark worried about tapeworm infection in other body sites?
A. When tapeworm larvae escape the stomach, they can travel to other parts of the body such as muscles, the liver, the eye, and even the brain to form cysticerci. B. The presence of T. solium in the brain can result in neurocysticercosis, a serious condition which has symptoms resembling those of brain tumors or epilepsy.
Which of the following could Tori's physician choose as a treatment for her yeast infection?
A. a topical over-the-counter ointment, such as clotrimazole or miconazole B. a single oral dose of fluconazole
How do blastoconidia and chlamydoconidia produced by yeast differ from bacterial endospores?
Blastoconidia and chlamydoconidia are spore structures produced by budding in yeasts, whereas bacterial endospores are produced by bacteria under extreme conditions.
Based on the lab results, which organism is most likely causing Tori's new symptoms?
Candida albicans
Which of the following represents the MOST LIKELY route of transmission for Michael's infection?
Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules
Which of the following statements best describes why the treatment for Tori's fungal infection may result in side effects to her own cells?
Fungal cells and human cells have a nucleus, multiple organelles, and 80S ribosomes for protein synthesis.
Why do we see an increase in the levels of IgE antibody in Michael's serum?
IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections.
Entamoeba histolytica, transmitted by contaminated food, grows on and in the cells lining the intestine and later within the intestinal wall. This results in dysentery. What best describes the relationship between E. histolytica and its host?
It is a parasitic relationship.
Which of the following best explains why Tori developed a new series of symptoms?
The antibiotics that treated Tori's primary respiratory infection also removed some of her normal bacterial flora, resulting in an overgrowth of other organisms.
During malarial infection, splenomegaly can occur. What causes this?
The spleen filters the blood and destroys old erythrocytes.
Which fungal genus is correctly matched to the class of disease it causes?
systemic mycosis: Candida
Leishmania parasites live within leukocytes. Which type of cell is most likely to harbor them?
macrophages
A major cause of helminthic infectious blindness is __________.
onchocerciasis
Which of the following infections are also caused by C. albicans?
oral thrush, fulminating disease
The Plasmodium life cycle is very complex, involving two hosts. Which of the choices shows the correct sequence of events in this cycle? 1. Red blood cells are infected. 2. Mosquito bite occurs. 3. Plasmodium enters the liver. 4. Red blood cells are destroyed. 5. Plasmodium grows and develops sporozoites.
c. 2, 5, 3, 1, 4, 2.Mosquito bite occurs 5. Plasmodium grows and develops sporozoites. 3. Plasmodium enters the liver. 1. Red blood cells are infected. 4. Red blood cells are destroyed.
