Mastering Microbiology CH 25

Poultry products are a likely source of infection by

Salmonella enterica.

Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning?

moderate vomiting and fever

Aflatoxin is a(n) ________ associated with ingestion of contaminated ________.

mycotoxin; peanuts

Helicobacter pylori can grow in the stomach because it

possesses an enzyme that neutralizes HCl.

Why does Dr. Clark request stool samples for examination?

-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. -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?

-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.

What is the attack rate of food poisoning among the group who attended the July 4 celebration?

105/150(100)= 70.0%

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

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.

Which of the findings listed below support the hypothesis?

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.

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?

Individuals who became ill may have consumed larger quantities of the food than individuals who did not become ill.

Which of the following findings are key to the cause of the outbreak?

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.

Which of the following is included in GALT?

Peyer's patches

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 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?

The cholera toxin causes the host cells to secrete large amounts of fluids and electrolytes.

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?

The salt and sugar in the rehydration solution will replace lost electrolytes and the water replaces the lost water.

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.

VIbrio cholera; exotoxins

Dental plaque is an example of

a biofilm.

Epidemics related to bacterial infection of the digestive system are typically caused by

contaminated food and water.

Clostridium difficile-associated diarrhea is usually preceded by

extended use of antibiotics.

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?

sewage contamination in drinking water

Bacteria present in the __________ can be phagocytosed by Paneth cells.

small intestine