Test Bank Digestive System Infections Chapter 24 nan

Nester’s Microbiology, 9e (Anderson)

Chapter 24 Digestive System Infections

1) 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

2) 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.

3) 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.

4) The most common infectious disease of humans is

A) the common cold.

B) dental caries.

C) hepatitis A.

D) halitosis.

E) influenza.

5) The principal cause of dental caries is

A) S. mutans.

B) S. salivarius.

C) S. mitis.

D) S. sanguis.

E) S. caries.

6) 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.

7) 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

8) 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.

9) 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.

10) 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.

11) 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

12) 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.

13) 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

14) The viral disease that characteristically infects the parotid glands is

A) measles.

B) mumps.

C) herpes.

D) chickenpox.

E) varicella.

15) 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.

16) 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.

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

A) flagella.

B) pili.

C) cilia.

D) pseudopodia.

E) a capsule.

18) 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.

19) 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.

20) 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.

21) 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

22) 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.

23) 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.

24) 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.

25) Shigella moves from cell to cell using

A) cilia.

B) actin tails.

C) pili.

D) flagella.

E) flagella AND pili.

26) 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

27) 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.

28) 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.

29) 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.

30) 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.

31) 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.

32) 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.

33) 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

34) The most notorious typhoid carrier was

A) Typhoid Tilly.

B) Typhoid Tom.

C) Typhoid Mary.

D) Typhoid Mark.

E) Typhoid salmonella.

35) 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

36) 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.

37) 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.

38) Viral gastroenteritis in infants and children is most commonly caused by

A) herpes.

B) hepatitis B.

C) rotavirus.

D) norovirus.

E) influenza virus.

39) 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.

40) 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.

41) Hepatitis A spreads via

A) the respiratory route.

B) blood transfusion.

C) body fluids.

D) the fecal-oral route.

E) the fecal route.

42) 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.

43) Intestinal protozoan infections are typically spread by

A) the respiratory route.

B) blood transfusion.

C) body fluids.

D) the fecal-oral route.

E) vectors.

44) The most commonly identified waterborne illness in the United States is

A) giardiasis.

B) amoebiasis.

C) cryptosporidiosis.

D) balantidiasis.

E) histoplasmosis.

45) 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.

46) Cryptosporidium parvum may infect

A) dogs.

B) pigs.

C) cattle.

D) humans.

E) All of the choices are correct.

47) Most North American outbreaks of Cyclospora cayetanensis have been associated with

A) imported cattle.

B) iguanas.

C) imported vegetables.

D) chickens.

E) foreign mosquitoes.

48) 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.

49) 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.

50) 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.

51) The bacteria primarily responsible for dental caries is Streptococcus mutans.

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

53) Helicobacter pylori appears connected to stomach cancer and ulcers.

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

55) The mumps virus initially infects the respiratory tract.

56) Virulent strains of Shigella typically carry an R plasmid.

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

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

59) Cyclosporiosis is transmissable from person to person.

60) Both Giardia lamblia and Cryptosporidium parvum are resistant to chlorine.

61) 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.

62) 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.

63) 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.

64) 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.

65) 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.

66) 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.

67) 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.

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.

69) 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.

70) 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.

71) 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.

72) 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

73) 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.

74) 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.

75) 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.

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.

77) 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.

78) 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.

79) What type of vaccine protects against mumps virus?

A) Toxoid

B) Conjugate

C) Attenuated

D) Subunit

E) Inactivated whole agent

80) 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.

81) Please select the INCORRECT statement regarding mumps and oral herpes.

A) Herpes simplex virus is an enveloped double-stranded DNA virus while mumps virus is an enveloped single-stranded RNA virus.

B) Both herpes simplex virus and mumps virus are extremely resistant to detergents and disinfectants.

C) Cells infected with HSV exhibit an intranuclear inclusion body; cells infected with mumps virus do not exhibit this body.

D) Herpes simplex virus and mumps virus are both transmitted in the saliva of infected people.

E) A person with HSV infection may experience recurrences while a person who has recovered from mumps has lifelong immunity.

82) Which of the following gastrointestinal pathogens produce A-B toxins?

A) Vibrio cholerae

B) Some strains of Shigella dysenteriae

C) Helicobacter pylori AND some strains of Shigella dysenteriae

D) Helicobacter pylori AND Vibrio cholerae

E) Vibrio cholerae AND some strains of Shigella dysenteriae

83) Which of the following media would you use to cultivate Vibrio cholerae?

A) Selective—containing NaCl and with basic pH.

B) Differential—containing NaCl and with basic pH.

C) Selective—containing HCl and with acidic pH.

D) Differential—containing HCl and with acidic pH.

E) V. cholerae cannot be cultured in the laboratory.

84) What are A/E lesions, produced by some strains of E. coli?

A) Inflammatory patches caused by the attachment of the bacteria to the intestinal lining by small suction appendages.

B) Intestinal abscesses that form after the bacteria have entered M cells, destroying them and causing bloody diarrhea.

C) Intestinal damage characterized by pedestals that form under bacterial cells as a result of induced actin rearrangement in the intestinal cell.

D) Cytoplasmic extensions induced in intestinal epithelial cells by the injection of superantigens via type III secretion systems.

E) Appendages used by E. coli strains to avoid phagocytosis and enter M cells of the intestinal epithelium.

85) Which of the following hepatitis viruses are transmitted by the fecal-oral route?

A) HAV and HBV

B) HAV and HCV

C) HAV, HBV, and HCV

D) HAV and HEV

E) All hepatitis viruses

86) Which of the following type of hepatitis is/are associated with liver cancer or cirrhosis?

A) Hepatitis A

B) Hepatitis B

C) Hepatitis C

D) Hepatitis B AND hepatitis C

E) Hepatitis A AND hepatitis B

87) Which of the following antigens are useful markers for hepatitis B infection?

A) HBsAg

B) HBcAg

C) HBcAg AND HBsAg

D) HBeAg

E) HBcAg, HBsAg, AND HBeAg

88) What does circulating HBeAg indicate about people with chronic HBV infection?

A) High levels of this antigen are associated with increased risk of liver cancer.

B) High levels of this antigen are associated with decreased risk of liver cancer.

C) Low levels of this antigen are associated with increased risk of liver cancer.

D) Antibodies against this antigen confer immunity to HBV.

E) IgM against this antigen indicate active viral replication.

89) Which statement about rotavirus gastroenteritis is false?

A) Rotaviruses are transmitted by the fecal-oral route.

B) Deaths related to the disease are usually caused by dehydration.

C) Most cases of the disease occur in infants and children.

D) Rotaviruses mainly infect the epithelial cells in the upper part of the small intestine.

E) There are no vaccines available for preventing rotavirus gastroenteritis.

90) Please identify the INCORRECT statement regarding bacterial diseases of the lower gastrointestinal system.

A) Cholera toxin—A-B toxin that causes intestinal cells to secrete HCl.

B) Of the four pathogenic strains of Shigella, S. dysenteriae is the most virulent.

C) Shiga toxin-producing E. coli may cause hemolytic uremic syndrome in an infected person.

D) There are more than 2,400 serotypes of Shigella, based on differences in their O, H, and K antigens.

E) Pseudomembranous colitis may develop in a person with Clostridium difficile infection.

Please read the scenario and answer the questions.

You are a nurse on a post-surgical ward. One of your patients is an elderly woman who has just had her gallbaldder removed. When you go into her room to check on her, you find that she has significant diarrhea, as well as fever and abdominal pain. You suspect that she has Clostridium difficile infection (CDI), and send a sample of her feces down to the hospital lab for analysis. The test result indicates that your patient does indeed have CDI. You make your patient comfortable and answer her questions about her illness.

91) You tell your patient that her CDI is caused by a bacterium belonging to the genus Clostridium. Which of the following is true of all Clostridia?

A) They are Gram-positive, rod-shaped, endospore-forming obligate anaerobes.

B) They are encapsulated, flagellated, toxin-producing aerobes.

C) They are Gram-negative, rod-shaped, endospore-forming obligate aerobes.

D) They are flagellated and always cause significant inflammation.

E) Clostridial infections only occur if a state of dysbiosis exists in the host.

92) Your patient wonders how she contracted CDI. Which of the following would be a good explanation for her?

A) She is elderly; elderly people frequently develop gastrointestinal complaints such as CDI. It is to be expected in an aging person.

B) She has been on antibiotic therapy because of her surgery. The antibiotics disrupted her normal intestinal microbiota, allowing any C. difficile present to flourish.

C) C. difficile is usually a community-acquired organism. She most likely came to the hospital already infected with it but it takes several days for signs and symptoms of CDI to appear.

D) Most surgical equipment is contaminated with C. difficile endospores, which are ubiquitous. Most likely your patient acquired CDI directly from her surgery. 

E) Nobody knows how people contract CDI. The causative bacterium is a common environmental organism and it is not known how it becomes pathogenic.

93) Clostridium difficile produces toxins that are involved in the pathogenesis of CDI. Which toxins are associated with ALL strains of this organism?

A) Toxin A and toxin B

B) CagA and vacA

C) CagA and toxin A

D) Binary toxin and VacA

E) Toxin A, toxin B, and binary toxin

94) Your patient asks what treatment she will be given for the CDI. You explain that initially, she will be taken off all antibiotics. This may cure her by

A) allowing her own gut normal microbiota to recover and to outcompete the C. difficile.

B) strengthening her innate and adaptive immune responses against the Clostridium difficile.

C) destroying any endospores that the C. difficile may have produced.

D) destroying any endospores that the C. difficile may have produced AND strengthening her innate and adaptive immune responses against the Clostridium difficile.

E) increasing antibiotic sensitivity in the Clostridium difficile, thereby weakening the pathogen so that the person's own immune system gets effectively rid of it.

95) You tell your patient that in some cases, CDI becomes chronic. One approach for treating this condition is a fecal microbiota transplant. How might this help a person with recurrent CDI?

A) Genetically modified microbiota is added to the disrupted system of the CDI patient. This creates a balanced population that can compete with the C. difficile.

B) Healthy, normal microbiota is added to the disrupted system of the CDI patient, creating a balanced population that outcompetes the C. difficile.

C) Healthy, normal microbiota is added to the disrupted system of the CDI patient. These new bacteria secrete exotoxins that kill the pathogenic C. difficile.

D) Healthy, normal microbiota is added to the disrupted system of the CDI patient. This stimulates the immune system of the person, eventually causing elimination of the C. difficile.

E) Normal microbiota from a person treated with prophylactic antibiotics is added to the disrupted system of the CDI patient. The antibiotic diffuses from the added microbiota, killing the C. difficile.

Please read the scenario and answer the questions.

Your brother is an enthusiatic hiker. He returns from a walking vacation and tells you that although he had a good time, he ran into a bit of trouble on one of the days he was away because he had got lost in the woods for several hours. Although he took enough food for the day, your brother ran out of water. Luckily, he came across a small stream and was able to fill up his water bottle and to finish his hike without any further problems. Your brother mentions as an aside that he must have eaten something bad while he was away, because he has had pretty bad diarrhea since he got back. He tells you he doesn't feel too bad, but that he has been having what he describes as "explosive diarrhea." He also complains of abdominal pain. You urge him to go to the doctor because you suspect that he may have something more than just food-related diarrhea. 

96) You suspect that your brother has giardiasis, caused by Giardia lamblia. Which of the following is NOT true about this disease?

A) The cysts of G. lamblia are are resistant to stomach acid and are infectious.

B) A person with giardiasis diarrhea is likely to eliminate G. lamblia cysts rather than trophozoites.

C) The causative organism has energy-metabolizing organelles called mitosomes.

D) Giardiasis is a zoonotic disease.

E) Chlorinated water may still contain G. lamblia because the cysts are resistant to this chemical.

97) The signs and symptoms of giardiasis vary among people. Which of the following is your brother unlikely to experience with his infection?

A) Bloody, frothy urine

B) Jaundice and malabsorption

C) Indigestion and gas

D) Nausea and vomiting

E) These all may be experienced with giardiasis.

98) Giardiasis involves 

A) treatment with mitochondria-targeting medications.

B) aerosol droplet transmission.

C) a Gram-negative causative agent.

D) a protozoan that uses fimbriae for attachment.

E) production of resistant, infectious cysts.

99) There are several stages in the life cycle of G. lamblia. Which is the correct sequence?

1. Trophozoites multiply in the intestine.

2. Mature cysts or trophozoites are released in feces.

3. Cysts pass through the stomach to the lower small intestine.

4. Dehydration in the large intestine stimulates formation of cysts.

5. Cysts enter the mouth by ingestion of contaminated food or water.

6. Trophozoites are released from the cysts.

A) 1, 2, 3, 4, 5, 6

B) 2, 3, 1, 5, 4, 6

C) 5, 2, 3, 1, 6, 4

D) 5, 3, 6, 1, 4, 2

E) 2, 5, 6, 1, 3, 4

100) You brother asks whether he will be given penicillin for his infection. What do you tell him?

A) Yes—G. lamblia has a peptidoglycan cell wall.

B) Yes—G. lamblia has 70S ribosomes.

C) No—G. lamblia is a virus.

D) No—G. lamblia is a protozoan.

E) No—G. lamblia has a protective LPS layer.