Deck 24: Digestive System Infections

Question 1

Part of the ability of S. mutans to result in dental caries depends on its ability to

A) invade plaque and dissolve the gums.
B) convert sucrose to lactic acid.
C) convert proteins to sugars.
D) attach to the gums.
E) convert lactic acid to sucrose.

Answer 1

B

Question 2

The initial attachment required for establishment of an intestinal infection is by

A) flagella.
B) pili.
C) cilia.
D) pseudopodia.
E) a capsule.

Answer 2

B

Question 3

The chronic inflammatory process involving the gums and tissues around the teeth is called

A) dental caries.
B) dental plaque.
C) periodontal disease.
D) root caries.
E) periodontal caries.

Answer 3

C

Question 4

Which of the following has shown some effectiveness in treating a herpes infection?

A) AZT
B) Protease inhibitors
C) Acyclovir
D) Cephalosporin
E) Broad spectrum antibiotics

Question 5

Most bacterial intestinal infections may be traced to all of the following EXCEPT

A) Vibrio species.
B) C. jejuni.
C) Salmonella species.
D) Enterobacteriaceae.
E) Haemophilus species.

Question 6

The most common infectious disease of humans is

A) the common cold.
B) dental caries.
C) hepatitis A.
D) halitosis.
E) influenza.

Question 7

The principal cause of dental caries is

A) S. mutans.
B) S. salivarius.
C) S. mitis.
D) S. sanguis.
E) S. caries.

Question 8

Who determined that the cholera outbreak in 1850s London was due to contaminated water and approached the problem by removing the pump handle at the contaminated site?

A) Pasteur
B) Snow
C) Koch
D) Smith
E) Semmelweis

Question 9

The diarrhea of cholera has been described as

A) a viscous fluid.
B) a rice water stool.
C) small in volume.
D) somewhat watery.
E) dysentery.

Question 10

Collections of bacteria that adhere to the surfaces of the teeth are called

A) dental caries.
B) dental plaque.
C) halitosis.
D) periodontal disease.
E) dental scum.

Question 11

Helicobacter pylori is able to survive in the stomach by its ability to produce

A) lactic acid from sugar.
B) ammonia from urease.
C) fatty acids from sebum.
D) neutralizing proteins from glucans.
E) ammonia from urea.

Question 12

Cholera is the classic example of a(n)

A) foodborne illness.
B) zoonosis.
C) very severe form of diarrhea.
D) opportunistic infection.
E) vector-borne disease.

Question 13

A painful finger infection attributable to herpes virus is known as a(n)

A) finger sore.
B) abrasion lesion.
C) furuncle.
D) herpetic whitlow.
E) nurse's lesion.

Question 14

Helicobacter pylori appears to have some connection with

A) acid reflux disease.
B) ulcers.
C) dental caries.
D) stomach cancer.
E) ulcers AND stomach cancer.

Question 15

The toxins involved in intestinal infections typically

A) kill cells by inhibiting DNA synthesis AND modify cell physiology resulting in increased secretion of water and electrolytes.
B) modify cell physiology resulting in increased secretion of water and electrolytes.
C) modify cell physiology resulting in decreased secretion of water and electrolytes.
D) kill cells by inhibiting DNA synthesis AND modify cell physiology resulting in decreased secretion of water and electrolytes.
E) kill cells by inhibiting protein synthesis AND modify cell physiology resulting in increased secretion of water and electrolytes.

Question 16

Mumps is a good candidate for elimination from the population due to

A) the existence of an effective vaccine.
B) a human-only reservoir.
C) the absence of a latent state.
D) a single serotype.
E) All of the choices are correct.

Question 17

This chemical compound, typically added to drinking water, makes enamel more resistant to dissolving in acid.

A) Calcium
B) Chlorine
C) Chloramine
D) Fluoride
E) Phosphate

Question 18

The viral disease that characteristically infects the parotid glands is

A) measles.
B) mumps.
C) herpes.
D) chickenpox.
E) varicella.

Question 19

Where in the body does the latent, non-infectious, non-replicating form of the herpes simplex virus persist?

A) Motor neurons
B) Sensory nerves
C) Red blood cells
D) Cranial nerves
E) Spinal cord

Question 20

The passage from the mouth to the anus is termed the

A) gut canal.
B) oral cavity.
C) grand canal.
D) gastrointestinal tract.
E) peristalsis.

Question 21

Vibrio cholerae and most salmonellae are

A) killed by acid conditions.
B) stimulated by acid conditions.
C) killed by low concentrations of salt.
D) killed by neutral conditions.
E) acidophiles.

Question 22

Most cases of Salmonella gastroenteritis have a(n)

A) water source.
B) human source.
C) plant source.
D) animal source.
E) human source AND animal source.

Question 23

Which of the following groups contain diarrhea-causing E. coli?

A) Enterotoxigenic 
B) Enteroinvasive 
C) Enteropathogenic 
D) Enterohemorrhagic 
E) All of the choices are correct

Question 24

A mysterious sequel to Campylobacter jejuni infections is

A) Reye's syndrome.
B) Guillain-Barré syndrome.
C) Tourette's syndrome.
D) Pasteur's syndrome.
E) Campylobacter syndrome.

Question 25

Shigella moves from cell to cell using

A) cilia.
B) actin tails.
C) pili.
D) flagella.
E) flagella AND pili.

Question 26

The most notorious typhoid carrier was

A) Typhoid Tilly.
B) Typhoid Tom.
C) Typhoid Mary.
D) Typhoid Mark.
E) Typhoid salmonella.

Question 27

The food products most commonly contaminated with Salmonella strains are

A) meat and seafood.
B) eggs and poultry.
C) milk and cheese.
D) fruit and vegetables.
E) eggs and fruit.

Question 28

The animal(s) often associated with Salmonella strains is/are

A) turtles.
B) iguanas.
C) baby chickens.
D) ducks.
E) All of the choices are correct.

Question 29

Which of these bacteria require a special medium and microaerophilic conditions?

A) Campylobacter jejuni
B) Escherichia coli
C) Pseudomonas aeruginosa
D) Staphylococcus aureus
E) Salmonella enterica

Question 30

The animal(s) frequently associated with Campylobacter jejuni is/are

A) turtles.
B) iguanas.
C) chickens.
D) dogs.
E) All of the choices are correct.

Question 31

Shigella and cholera toxin both

A) have an A-B arrangement.
B) work through ADP ribosylation.
C) increase cAMP levels.
D) prevent protein synthesis.
E) are endotoxins.

Question 32

Viral gastroenteritis that affects people of all ages and usually lasts less than 3 days is caused by

A) herpes.
B) hepatitis B.
C) norovirus.
D) rotavirus.
E) influenza virus.

Question 33

The most common chronic blood-borne infection in the U.S. is

A) hepatitis D.
B) hepatitis C.
C) hepatitis B.
D) hepatitis A.
E) none of these.

Question 34

Which of the following E. coli serovars produces a toxin somewhat similar to that produced by Shigella dysenteriae?

A) Enterotoxigenic 
B) Enteroinvasive 
C) Enteropathogenic 
D) Enterohemorrhagic 
E) All of the choices are correct.

Question 35

Which of the following E. coli serovars give rise to a disease similar to that caused by Shigella sp.?

A) Enterotoxigenic 
B) Enteroinvasive 
C) Enteropathogenic 
D) Enterohemorrhagic 
E) All of the choices are correct.

Question 36

The primary treatment for cholera is

A) the administration of antibiotics.
B) vaccination AND the administration of antibiotics.
C) by blood transfusion AND simple rehydration.
D) simply rehydration.
E) vaccination AND by blood transfusion.

Question 37

Viral gastroenteritis in infants and children is most commonly caused by

A) herpes.
B) hepatitis B.
C) rotavirus.
D) norovirus.
E) influenza virus.

Question 38

The symptoms of cholera are due to the action of

A) an endotoxin.
B) an exotoxin.
C) modified mucus.
D) flagella.
E) an exotoxin AND an endotoxin

Question 39

In which of these organs does a carrier of typhoid bacilli maintain the bacteria?

A) Liver
B) Gallbladder
C) Peyer's patches
D) Colon
E) Liver AND Peyer's patches

Question 40

A common source of cholera infection is

A) acid rain.
B) unpasteurized milk.
C) fecal contaminated water.
D) boiled water.
E) acid rain AND boiled water.

Question 41

Both Giardia lamblia and Cryptosporidium parvum are resistant to chlorine.

Question 42

The bacteria primarily responsible for dental caries is Streptococcus mutans.

Question 43

The infectious dose for cholera is much larger than that for shigellosis.

Question 44

Cyclosporiosis is transmissable from person to person.

Question 45

Amebiasis

A) is caused by Cryptosporidium parvum.
B) often causes a bloody diarrhea.
C) is an infection of the stomach.
D) is restricted to temperate climates.
E) is caused by Cryptosporidium parvum AND often causes a bloody diarrhea.

Question 46

Virulent strains of Shigella typically carry an R plasmid.

Question 47

Helicobacter pylori appears connected to stomach cancer and ulcers.

Question 48

Sucrose is one of the major contributors to the development of dental caries.

Question 49

Cyclospora cayetanensis has, so far, not been identified with an animal source.

Question 50

The oocytes of Cyclospora cayetanensis

A) are mature when eliminated in the stool.
B) do not contain sporozoites when passed in the feces.
C) are smaller than the oocytes of Cryptosporidium parvum.
D) give rise to three sporozoites.
E) contain sporozoites when passed in the feces.

Question 51

Intestinal protozoan infections are typically spread by

A) the respiratory route.
B) blood transfusion.
C) body fluids.
D) the fecal-oral route.
E) vectors.

Question 52

The saliva of asymptomatic carriers of herpes simplex is not infectious.

Question 53

Giardiasis may be contracted from

A) another person.
B) clear mountain streams.
C) chlorinated city water.
D) cold filtered beer.
E) another person, clear mountain streams, AND chlorinated city water.

Question 54

Entamoeba histolytica

A) causes amebiasis.
B) may form cysts.
C) cysts survive passage through the stomach.
D) may produce a cytotoxic enzyme.
E) All of the choices are correct.

Question 55

The most commonly identified waterborne illness in the United States is

A) giardiasis.
B) amoebiasis.
C) cryptosporidiosis.
D) balantidiasis.
E) histoplasmosis.

Question 56

Hepatitis A spreads via

A) the respiratory route.
B) blood transfusion.
C) body fluids.
D) the fecal-oral route.
E) the fecal route.

Question 57

The mumps virus initially infects the respiratory tract.

Question 58

Most North American outbreaks of Cyclospora cayetanensis have been associated with

A) imported cattle.
B) iguanas.
C) imported vegetables.
D) chickens.
E) foreign mosquitoes.

Question 59

Which of the following is NOT a mechanism of spread of HBV?

A) Blood
B) Blood products
C) Saliva
D) Semen
E) These are all mechanisms of spread for HBV.

Question 60

Cryptosporidium parvum may infect

A) dogs.
B) pigs.
C) cattle.
D) humans.
E) All of the choices are correct.

Question 61

Please select the definition regarding aspects of the digestive system that is INCORRECT.

A) Cariogenic-causing dental caries.
B) Dysentery-diarrhea characterized by fecal pus and blood.
C) Cirrhosis-liver scarring that interferes with function.
D) Gingivitis-inflammation of the teeth and gums.
E) Dysbiosis-imbalance of the intestinal normal microbiota.

Question 62

How does H. pylori survive the acidic conditions of the stomach?

A) Producing urease, an enzyme that converts urea to ammonia, thereby creating an alkaline microenvironment.
B) Burrowing within the layer of mucus that coats the stomach lining.
C) Producing urease, an enzyme that converts ammonia to urea, thereby creating an alkaline microenvironment.
D) Producing urease, an enzyme that converts urea to ammonia, thereby creating an alkaline microenvironment AND burrowing within the stomach mucus layer.
E) Producing urease, an enzyme that converts ammonia to urea, thereby creating an alkaline microenvironment AND covering its flagella with protective sheaths.

Question 63

Explain how Vibrio cholerae causes cholera without apparent damage to the intestinal epithelium.

A) This microbe causes destruction of the cellular structures underneath the intestinal epithelium-this is what induces the watery rice-stool characteristic of the illness. This leaves the overlying intestinal epithelium intact.
B) This microbe directly invades the intestinal epithelial cells, but does not kill them. Instead, while multiplying inside them, it causes them to secrete large amounts of chloride ions. This induces water to follow by osmosis, resulting in the watery rice-stool characteristic of the illness.
C) This microbe attaches to the surface of intestinal epithelial cells, producing an exotoxin that causes the epithelium to secrete chloride ions. This induces large amounts of water to follow by osmosis, resulting in the watery rice-stool characteristic of the illness.
D) The inflammatory reaction to the presence of this microbe causes the watery rice-stool characteristic of the illness. Therefore, it's technically the immune response that initiates the disease, although this response is induced by the presence of the microbe on the intestinal epithelium.
E) This microbe attaches to the surface of intestinal epithelial cells, producing an endotoxin that causes the epithelium to secrete potassium ions. This induces small amounts of water to follow by osmosis, resulting in the watery rice-stool characteristic of the illness.

Question 64

A patient presents with bad halitosis, red and swollen gingiva, and several loose teeth. You take a sample from the gum line and after performing a stain, note spirochete bacteria as well as some bacilli. This patient likely has 

A) gingivitis.
B) dental caries.
C) periodontal disease.
D) acute necrotizing ulcerative gingivitis.
E) dental caries AND acute necrotizing ulcerative gingivitis.

Question 65

Why don't medications such as acyclovir cure oral herpes simplex infections?

A) Acyclovir is an antiviral medication, but oral herpes is caused by a bacterium.
B) Acyclovir is an antibacterial medication, but oral herpes is caused by a virus.
C) Herpes simplex virus DNA persists in a latent form that is not removed by acyclovir.
D) Herpes simplex virus RNA persists in a latent form that is not removed by acyclovir.
E) Herpes simplex virus forms endospores that are resistant to all medications.

Question 66

Which of the following is/are treatment(s) for advanced periodontal disease?

A) Removing plaque and tartar.
B) Cleaning out gingival crevices AND removing plaque and tartar.
C) Removing plaque and tartar AND minor gum surgery.
D) Brushing and flossing, filling cavities with amalgam, AND antibiotic therapy.
E) Cleaning out gingival crevices, minor gum surgery, AND antibiotic therapy.

Question 67

What type of vaccine protects against mumps virus?

A) Toxoid
B) Conjugate
C) Attenuated
D) Subunit
E) Inactivated whole agent

Question 68

Why does removal of plaque reduce the chance of forming cavities?

A) Plaque is a biofilm; it contains cariogenic bacteria, the metabolic byproducts of which facilitate tooth decay.
B) Plague causes a significant drop in oral pH. The more acidic condition causes tooth decay.
C) Plaque is a polysaccharide covering on tooth enamel. It contains tiny acid-soaked sponges that decay teeth.
D) Removing plaque involves brushing. A coincidental side benefit of brushing is removal all oral bacteria.
E) Removing plaque actually does not impact the development of cavities. Cavities have a genetic component and cannot be prevented.

Question 69

Which of the following is not a typical sign or symptom of H. pylori gastritis?

A) Belching
B) Bloating
C) Vomiting
D) Pain
E) Fever

Question 70

Please select the False statement regarding tooth decay.

A) Lactic acid in the mouth forms as a result of fermentation of fructose.
B) Cariogenic bacteria can ferment polysaccharides stored in granules.
C) Tooth decay never occurs if Streptococcus mutans is absent.
D) Plaque forms when oral streptococci adhere to the proteinaceous pellicle on teeth.
E) Cariogenic bacteria such as Streptococcus mutans are acidophiles.

Question 71

Once H. pylori is in a host's stomach, what happens?

A) The bacteria move away from the neutral mucus-secreting epithelium toward the acidic stomach lumen.
B) H. pylori moves from the basic stomach lumen up toward the neutral esophagus.
C) The bacteria move away from the acidic stomach lumen toward the neutral mucus-secreting epithelial layer.
D) The bacteria move away from the acidic stomach lumen toward the neutral small intestine.
E) H. pylori moves from the neutral small intestine toward the acidic stomach lumen.

Question 72

What are possible complications of mumps?

A) Orchitis and infertility
B) Meningitis
C) Miscarriage
D) Sudden onset deafness
E) All of the answer choices are correct.

Question 73

Why are older people (over 65) more likely to lose teeth than to develop cavities?

A) Cavities are less common because the pits and fissures on teeth that bacteria can colonize wear down over time. However, older adults are more likely to develop periodontal disease that can lead to the loss of teeth.
B) Older adults never eat sugar, because of the risk of type 2 diabetes that increases with age. However, they are likely to develop periodontal disease, that can lead to the loss of teeth.
C) As adults age, the enamel layer on their teeth surfaces increases in strength, making it almost impossible for bacteria to cause decay. However, as the enamel thickens, the gums weaken, so teeth can fall out and be lost.
D) As adults age, their tooth enamel becomes less porous. This prevents bacteria from colonizing the teeth, preventing the development of decay. However, as people get older, their saliva becomes more acidic, and this causes periodontal disease.
E) The mouth normal microbiota changes over time. In children the predominant bacteria are those that cause tooth decay. However, in adults, the predominant bacteria are those that cause gum disease and tooth loss.

Question 74

Why is it that the tongue and cheek epithelium doesn't provide a sufficient anaerobic environment for plaque anaerobes to grow, but the surface of teeth might?

A) The epithelium is supplied with oxygen by capillary beds. This makes it a relatively aerobic environment and hostile to anaerobes.
B) The tooth enamel is supplied with oxygen by capillary beds. This makes it a relatively anaerobic environment and hostile to aerobes.
C) The surface of the tongue and cheek are constantly scraped by the action of consuming food. Layers of bacterial growth that might help to supply an anaerobic environment are scraped away, exposing lower levels to oxygen-rich air.
D) The surface of teeth like molars have many pits and crevices in which bacteria can grow. The bottoms of these pits are anaerobic. This isn't possible on the very smooth surface of the tongue and cheek epithelium.
E) The epithelium is supplied with carbon dioxide by capillary beds. This makes it a relatively anaerobic environment, friendly to obligate anaerobes.

Question 75

Why might it be more difficult to prepare a vaccine against noroviruses than against rotaviruses?

A) We haven't been able to culture noroviruses in a lab setting yet. Without a starting culture, we can't create a vaccine.
B) Noroviruses are RNA viruses, where rotaviruses are DNA viruses. RNA viruses mutate far more easily than DNA viruses, so we COULD make a vaccine, but it would be rendered useless fairly quickly as the virus mutates.
C) We lack a proper culturing method for large-scale production of target cells for norovirus, whereas we have such a system for the target cells of rotaviruses. Without a system to get large numbers of target cells, we can't produce a vaccine.
D) Norovirus is much more infectious than rotavirus. As such, it's much harder to work with safety. This makes production of a vaccine too dangerous and unpredictable.
E) This question is misleading. It has been relatively simple to create vaccines against both of these virus types.

Question 76

Which statement regarding CagA and VacA of H. pylori is INCORRECT?

A) Strains of H. pylori that produce CagA are associated with stomach cancer.
B) CagA is delivered into host cells by a secretion system.
C) VacA is an A-B toxin that increases urea flow into the stomach.
D) VacA interferes with the function of T cells.
E) CagA interferes with cell signaling and promotes inflammation.

Question 77

Only one serotype of mumps virus is known. Why is this important?

A) It has been possible to create an effective vaccine that protects against this virus.
B) When only one serotype of a virus exists, there is a great risk of mutation in that agent.
C) Herd immunity is not possible in a population if there is only one serotype of a virus.
D) It is not possible to create a vaccine for an infectious agent if there is only one serotype of the agent.
E) B cells and cytotoxic T cells are unable to respond to a virus if there is only a single serotype of that virus.

Question 78

Why is it difficult to determine the causative agents of periodontal disease?

A) The agents are fastidious bacteria that cannot be cultured in the laboratory.
B) Identification requires 16S rDNA sequencing and not all bacteria have this gene.
C) The infections are polymicrobial, so multiple species of interacting bacteria are involved.
D) The causative agents are typically viruses, which are difficult to identify.
E) The causative agents are encased in biofilm polysaccharides that cannot be removed.

Question 79

Would you expect an individual with giardiasis who has diarrhea to be more likely to transmit the disease than an individual with giardiasis who does NOT have diarrhea? Why or why not?

A) No. This illness is spread by respiratory droplets, so diarrhea as a symptom shouldn't matter for transmission of the disease.
B) No. This illness is spread by sexual contact, so diarrhea as a symptom shouldn't matter for transmission of the disease.
C) Yes. This illness is spread by the fecal-oral route, so presence of diarrhea as a symptom should dramatically increase the possibility of transmission of infection.
D) Yes. This illness is spread by insects that feed on contaminated fecal matter, becoming infected themselves. The disease is spread to new individuals when these infected insects bite a susceptible person, transmitting the cysts of the protozoan. As such, diarrhea as a symptom would increase the risk of transmission through biting insects to new individuals.
E) No. This illness is spread when people ingest cysts, and a person with severe diarrhea excretes primarily trophozoites; an asymptomatic person is more likely to excrete cysts and is therefore more infectious.

Question 80

Which of the following is specific to H. pylori strains associated with stomach cancer?

A) They are microaerophilic.
B) They have sheathed flagella.
C) The are acidophilic.
D) They produce CagA.
E) They produce VacA.