Microbiology: An Introduction, 13e (Tortora et al.)
Chapter 25 Microbial Diseases of the Digestive System
25.1 Multiple-Choice Questions
1) Which of the following is directly involved in the initiation of dental caries?
A) sucrose
B) lysozyme
C) lactic acid
D) crevicular fluid
E) dentin
2) Clostridium difficile-associated diarrhea is usually preceded by
A) eating contaminated food.
B) a blood transfusion.
C) extended use of antibiotics.
D) improper food storage.
E) travel to an underdeveloped country.
3) Which of the following statements about salmonellosis is FALSE?
A) It is a bacterial infection.
B) Severity of disease depends on number of organisms ingested.
C) A healthy carrier state exists.
D) The mortality rate is high.
E) It is often associated with poultry products.
4) Disease-causing exotoxins are produced by all of the following organisms EXCEPT
A) Clostridium perfringens.
B) Vibrio cholerae.
C) Shigella dysenteriae.
D) Staphylococcus aureus.
E) Clostridium botulinum.
5) Which one of the following diseases of the gastrointestinal system is transmitted by the
respiratory route?
A) staphylococcal enterotoxicosis
B) mumps
C) Vibrio gastroenteritis
D) bacillary dysentery
E) traveler’s diarrhea
6) The digestive tract is essentially one long tube. The order of the structures, beginning with the
mouth, is
A) pharynx, esophagus, stomach, small intestine, large intestine.
B) esophagus, pharynx, stomach, small intestine, large intestine.
C) pharynx, esophagus, stomach, large intestine, small intestine.
D) esophagus, stomach, pharynx, small intestine, large intestine.
E) pharynx, stomach, esophagus, small intestine, large intestine.
7) Which of the following helminthic diseases is a common infestation found in the southeastern
United States?
A) Enterobius vermicularis
B) Ascaris lumbricoides
C) Taenia saginata
D) Trichuris trichiura
E) Echinococcus granulosus
8) Poultry products are a likely source of infection by
A) Helicobacter pylori.
B) Salmonella enterica.
C) Vibrio cholerae.
D) Shigella spp.
E) Clostridium perfringens.
9) All of the following infections can result from drinking contaminated water EXCEPT
A) Cyclospora infection.
B) giardiasis.
C) trichinellosis.
D) cholera.
E) cryptosporidiosis.
10) Which of the following organisms is shed in the feces of humans and animals, including
beavers, and can contaminate water?
A) Giardia lamblia
B) Escherichia coli
C) Taenia spp.
D) Vibrio parahaemolyticus
E) Entamoeba histolytica
11) In humans, beef tapeworm infestations are acquired by ingesting
A) the eggs of Taenia saginata.
B) segments of Taenia solium tapeworms.
C) water contaminated with Diphyllobothrium latum eggs.
D) cysticerci of Taenia saginata in undercooked meat.
E) cysticerci of Taenia solium in undercooked meat.
12) Which of the following statements about staphylococcal food poisoning is FALSE?
A) It is caused by ingesting an enterotoxin.
B) It can be prevented by adequate refrigeration of food.
C) It can be prevented by heating foods to 50°C for 15 minutes.
D) It is treated by replacing water and electrolytes.
E) It is characterized by rapid onset and short duration of symptoms.
13) The most common cause of traveler’s diarrhea is
A) Shigella spp.
B) Salmonella enterica.
C) Giardia lamblia.
D) Escherichia coli.
E) Campylobacter jejuni.
14) Acute gastroenteritis that occurs after an incubation period of two to three days, persists for
about a week, and commonly affects children is probably caused by
A) Giardia.
B) rotavirus.
C) Salmonella.
D) Staphylococcus aureus.
E) Trichinella.
15) Which of the following is mismatched?
A) Echinococcus granulosus – most benign of human tapeworm infections
B) Taenia solium – cysticerosis
C) trichinellosis – humans eat larva of parasite in undercooked meat
D) pinworm infestation – humans ingest parasite’s eggs
E) hookworm infestation – heavy infections may cause pica
16) Thorough cooking of food will prevent all of the following EXCEPT
A) trichinellosis.
B) beef tapeworm.
C) staphylococcal food poisoning.
D) salmonellosis.
E) shigellosis.
17) Most of the normal microbiota of the digestive system are found in the
A) mouth.
B) stomach.
C) stomach and small intestine.
D) small intestine and large intestine.
E) accessory structures.
18) Gums bleeding while brushing one’s teeth is most commonly associated with
A) halitosis.
B) cavities.
C) gingivitis.
D) periodontitis.
E) trench mouth.
19) Typhoid fever differs from salmonellosis in that in typhoid fever
A) the microorganisms multiply within macrophages.
B) the organism is only spread in the feces of humans.
C) the incubation period is much shorter.
D) the organism first invades the intestinal mucosa.
E) infection occurs due to ingestion of endospores.
20) Which of the following organisms is likely to be transmitted via contaminated shrimp?
A) Trichinella spiralis
B) Vibrio parahaemolyticus
C) Giardia lamblia
D) Clostridium perfringens
E) Staphylococcus aureus
21) Which of the following organisms is likely to be transmitted via undercooked pork and
horse?
A) Salmonella enterica
B) Staphylococcus aureus
C) Trichinella spiralis
D) Entamoeba histolytica
E) Shigella spp.
22) A vaccine to provide active immunity to HBV is prepared from
A) viruses grown in tissue culture.
B) genetically modified yeast.
C) pooled gamma globulin.
D) viruses grown in embryonated eggs.
E) viral particles in patients.
23) Aflatoxin is a(n) ________ associated with ingestion of contaminated ________.
A) mycotoxin; peanuts
B) mycotoxin; rye or other cereal grains
C) enterotoxin; peanuts
D) enterotoxin; rye or other cereal grains
E) endotoxin; peanuts
24) Which of the following causes inflammation of the liver?
A) Salmonella enterica
B) Shigella spp.
C) hepatitis A virus
D) Vibrio cholerae
E) Escherichia coli
25) “Rice water stools” are characteristic of
A) salmonellosis.
B) cholera.
C) bacillary dysentery.
D) amebic dysentery.
E) tapeworm infestation.
26) Epidemics related to bacterial infection of the digestive system are typically caused by
A) biological vectors.
B) contaminated food and water.
C) unpasteurized milk.
D) the respiratory route.
E) exposure to contaminated soil.
27) Many bacterial infections of the lower digestive tract are treated with
A) antitoxin.
B) penicillin.
C) water and electrolytes.
D) quinacrine.
E) thorough cooking.
28) Dental plaque is an example of
A) a pellicle.
B) a biofilm.
C) gingivitis.
D) dentin.
E) tooth enamel.
29) Which of the following is mismatched?
A) ergot – gangrene
B) Salmonella endotoxin – lyses red blood cells
C) Vibrio enterotoxin – secretion of Cl–, K+, and H2O
D) aflatoxin – liver cancer
E) shiga toxin – tissue destruction
30) Bacterial intoxications differ from bacterial infections of the digestive system in that
intoxications
A) are transmitted via contaminated water.
B) are more severe.
C) have shorter incubation times.
D) are treated with antibiotics.
E) are accompanied by high fever.
31) The most common mode of HAV transmission is
A) contamination of food during preparation.
B) respiratory route.
C) blood transfusion.
D) contaminated hypodermic needles.
E) airborne.
32) Which of the following correctly lists the stages of tooth decay?
A) plaque accumulation, destruction of enamel, advancement of decay through enamel, decay in
dentin, decay in tooth pulp
B) decay in dentin, plaque accumulation, destruction of enamel, advancement of decay through
enamel, decay in tooth pulp
C) plaque accumulation, destruction of enamel, decay in tooth pulp, advancement of decay
through enamel, decay in dentin
D) destruction of enamel, advancement of decay through enamel, plaque accumulation, decay in
dentin, decay in tooth pulp
E) destruction of enamel, plaque accumulation, advancement of decay through enamel, decay in
dentin, decay in tooth pulp
33) A 38-year-old man had onset of fever, chills, nausea, and myalgia while vacationing on the
Gulf of Mexico. On April 29, he had eaten raw oysters and gone wading in the warm coastal
waters. On May 2, he was admitted to a hospital because of a fever of 39°C and two circular
necrotic lesions on the left leg. He had a history of alcoholic liver disease. He was transferred to
the ICU; therapy with antibiotics was initiated. On May 4, he died. Which of the following is the
most likely cause?
A) Bacillus cereus
B) Cyclospora cayetanensis
C) Salmonella Typhi
D) Vibrio vulnificus
E) hepatitis C virus
34) Which of the following is included in GALT?
A) thymus
B) Peyer’s patches
C) tonsils
D) liver
E) salivary glands
35) Microscopic examination of a patient’s fecal culture shows spiral bacteria. The bacteria
probably belong to the genus
A) Campylobacter jejuni.
B) Escherichia coli.
C) Salmonella Typhi.
D) Shigella spp.
E) Vibrio cholerae.
36) Which of the following pertains to typhoid fever?
A) It is typically acquired via ingestion of contaminated eggs.
B) Enterotoxin spreads via the blood.
C) It is caused by several different species of Salmonella.
D) Causative microorganism multiplies in patient phagocytes.
E) It is also called bacillary dysentery.
37) All of the following are gram-negative rods that cause gastroenteritis EXCEPT
A) Clostridium perfringens.
B) Escherichia coli.
C) Salmonella Typhi.
D) Shigella spp.
E) Yersinia enterocolitica.
38) Helicobacter pylori can grow in the stomach because it
A) hides in macrophages.
B) makes a capsule.
C) possesses an enzyme that neutralizes HCl.
D) makes HCl.
E) invades epithelial cells.
39) All of the following are eukaryotic organisms that cause diarrheal disease EXCEPT
A) Cryptosporidium.
B) Cyclospora.
C) Entamoeba.
D) Giardia.
E) Campylobacter.
40) All of the following pertain to pinworm infections EXCEPT
A) transmission is typically by contact with fomites or inhalation of eggs.
B) diagnosis is by detecting eggs on transparent tape pressed to the perianal area.
C) all family members living with the patient must also be treated.
D) it is most commonly transmitted by cysts in water.
E) it is a helminth disease.
41) What is a Dane particle?
A) the chlorine-resistant virus that causes HAV
B) the infectious virion that causes HBV
C) the spherical particles found in serum of patients with HBV
D) the filamentous particles that cause HAV
E) another name for an HBV surface antigen
42) Which of the following is mismatched?
A) beef – E. coli O157:H7
B) custard and cream pies – Staphylococcus aureus
C) eggs – Trichinella spiralis
D) chicken – Campylobacter jejuni
E) oysters – Vibrio parahaemolyticus
Situation 25.1
Following a county fair, 160 persons complained of gastrointestinal symptoms. Symptoms
included diarrhea (84 percent), abdominal cramps (96 percent), nausea (84 percent), vomiting
(82 percent), body aches (50 percent), fever (60 percent; median body temperature = 38.3°C);
median duration of illness 6 days (range 10 hr to 13 days).
43) In Situation 25.1, fecal samples should be cultured for all of the following EXCEPT
A) Salmonella enterica.
B) Shigella spp.
C) Campylobacter jejuni.
D) enteropathogenic Escherichia coli.
E) Giardia lamblia.
44) In Situation 25.1, fecal samples were found to be negative when cultured. The next step in
diagnosing the cause of illness would be
A) to begin antibiotic therapy.
B) blood cultures.
C) microscopic examination of feces for oocysts.
D) microscopic examination of feces for viruses.
E) muscle biopsy.
45) Table 25.1
Food Relative Risk
Black beans 0.58
Corn soup 0.75
Jalapeño peppers 34.13
Roma tomatoes 5.40
The relative risks shown in Table 25.1 were calculated for foods suspected of transmitting
Salmonella. Which food is the most likely source of infection?
A) black beans
B) corn soup
C) jalapeño peppers
D) roma tomatoes
E) The answer cannot be determined based on the information provided.
46) Which structure or component of the small intestine is important to antimicrobial defense?
A) salivary glands
B) stomach acid
C) Paneth cells
D) gall bladder
E) crevicular fluid
47) A rushed homemaker prepared a stew from a large cut of beef but the family only consumed
a small portion for dinner. The still-hot large pot was placed in the refrigerator overnight. The
next day the stew was warmed for lunch. By the evening the entire family was suffering from
varying degrees of diarrhea, abdominal cramping and nausea. You most likely suspect the culprit
of this event is
A) Salmonella.
B) H. pylori.
C) Shigella.
D) C. perfringes.
E) B. cereus.
48) Which is true of the Mumps virus?
A) It is transmitted by the fecal-oral route.
B) It typically begins with symptoms of gastroenteritis.
C) The portal of entry is the respiratory route.
D) A component vaccine is part of the MMR.
E) Male sterility occurs in 40% of infections.
49) Which is NOT true of HBV?
A) 1/3 of the world population shows serological evidence of past infection.
B) 5% of acute HBV infections progress to chronic infection.
C) Filamentous particles are not infectious.
D) Acute HBV infection may be subclinical.
E) Individuals infected as adults are the most likely to become carriers of the virus.
50) A young child received a red-eared slider turtle as a birthday gift. Within a week the child
was suffering from a severe gastroenteritis that required a visit to urgent care. What is the child
likely suffering from?
A) salmonellosis
B) Campylobacter infection
C) shigellosis
D) hepatitis A infection
E) cholera
25.2 True/False Questions
1) Campylobacter gastroenteritis is the leading cause of foodborne illness in the United States.
2) Clostridium perfringens typically causes a self-limiting gastroenteritis.
3) Bacterial infections, but not intoxications, can cause diarrhea.
4) An outbreak of viral gastroenteritis occurs in a pediatrics ward. Rotavirus is the most likely
causative agent.
5) Aflatoxin poisoning is associated with liver cancer.
6) Approximately 30 percent of the body’s immune system is located in the intestinal tract.
7) Humans infected with Enterobius vermicularis may have hydatid cysts within their lungs or
other organs.
8) Gastroenteritis due to ingestion of food contaminated with Staphylococcus aureus is due to
intoxication by enterotoxins.
9) EHEC is a major cause of diarrhea in developing countries and may result in the death of
small children.
10) H. pylori is able to survive the acidic environment of the stomach as a result of adaptations
that allow it to increase the pH of the immediate environment.
25.3 Essay Questions
1) Mary made her family’s favorite cream of broccoli soup for lunch. Lunch was forgotten when
her son suddenly remembered he had a soccer game at noon. The family finally returned several
hours later and sat down to eat. Although Mary reheated the soup (which had been left out at
room temperature while they were gone), why is this no guarantee that Mary and her family will
not become sick due to food poisoning?
2) Discuss why cholera epidemics are often associated with floods.
3) Compare the modes of transmission for hepatitis A, B, and C.
4) Describe the process of periodontal disease.
5) Multiple pathovars of E. coli are well characterized. Identify four different pathogenic strains
and discuss the mechanism of disease for each.
6) Thinking of a mumps infection, how do the symptoms involve the GI tract, yet lead to
airborne transmission of the disease? Why isn’t the disease transmitted by fecal-oral
contamination instead?