Cholera is a waterborne pathogen that causes severe gastrointestinal disease. The organism is a slightly curved, gram-negative rod that likes to grow in the small intestine and causes watery stools and violent vomiting. Complete the following statement: Cholera is caused by the bacterium, __________ and produces __________ that result in severe diarrhea.
answer
VIbrio cholera; exotoxins
question
During his presentation to the Microbiology Club, Cody mentions that the cholera epidemic in 2010 came shortly after an earthquake. He also mentions that other cholera epidemics had occurred following natural disasters such as flooding. Which of the following has the greatest impact on the number of cholera cases after a natural disaster?
answer
sewage contamination in drinking water
question
The pathogenesis of Vibrio cholerae is due to the organism's ability to produce cholera toxin. This is an A-B toxin that affects host cells in the small intestine. Which of the following correctly describes the mechanism of the toxin?
answer
The cholera toxin causes the host cells to secrete large amounts of fluids and electrolytes.
question
In untreated individuals, the mortality rate of cholera can be as high as 50%, but in individuals that are given oral rehydration therapy, fatalities are rare. Oral rehydration therapy involves treating the patients with an oral suspension of salt, sugar, and water. Which of the following choices explains why this suspension is used instead of pure water to treat cholera infections?
answer
The salt and sugar in the rehydration solution will replace lost electrolytes and the water replaces the lost water.
question
Why does Dr. Clark request stool samples for examination?
answer
-He will have the laboratory prepare the samples for an ova and parasite (O) exam. Fresh or preserved stool samples can be observed microscopically for the presence of parasites or their eggs/cysts.
-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.
question
Which of the following represents the MOST LIKELY route of transmission for Michael's infection?
answer
Foodborne - Eating undercooked, unwashed, or otherwise contaminated food that contained parasitic propagules
question
Which of the following organisms is most likely the causative agent of Michael's tapeworm infection?
answer
Taenia solium
question
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?
answer
Tapeworms utilize diffusion to absorb nutrients from the host's digestive system.
question
Why do we see an increase in the levels of IgE antibody in Michael's serum?
answer
IgE is the class of antibodies involved in hypersensitivities such as allergies and parasitic infections.
question
What is the treatment that Dr. Clark will most likely recommend?
answer
Praziquantel or albendazole, drugs that target eukaryotic parasites with minimal side effects in the host.
question
Why was Dr. Clark worried about tapeworm infection in other body sites?
answer
-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.
-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.
question
What is the attack rate of food poisoning among the group who attended the July 4 celebration?
answer
105/150(100)= 70.0%
question
Some of the individuals who said they ate the barbecue with the sauce did not become ill. Which one of the following is the most likely explanation for such an occurrence?
answer
Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.
question
Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning?
answer
moderate vomiting and fever
question
Which of the findings listed below support the hypothesis?
answer
Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units.
Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units.
Protein levels within the ileum loop fluid are increased up to 1000 units of toxin.
question
Which of the following findings are key to the cause of the outbreak?
answer
Large quantities of meat were prepared and kept warm for a long time before they were served.
The sauce was prepared on an overcrowded steam table and, as a result, did not reach an appropriate temperature to kill any organisms.
question
Which of the following is included in GALT?
answer
Peyer's patches
question
Bacteria present in the __________ can be phagocytosed by Paneth cells.
answer
small intestine
question
Dental plaque is an example of
answer
a biofilm.
question
Clostridium difficile-associated diarrhea is usually preceded by
answer
extended use of antibiotics.
question
Poultry products are a likely source of infection by
answer
Salmonella enterica.
question
Epidemics related to bacterial infection of the digestive system are typically caused by
answer
contaminated food and water.
question
Helicobacter pylori can grow in the stomach because it
answer
possesses an enzyme that neutralizes HCl.
question
Aflatoxin is a(n) ________ associated with ingestion of contaminated ________.
answer
mycotoxin; peanuts
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