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Exam 3β
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Questions in this quiz (31)
11. Which of the following would be characteristic of a highly evolved pathogen?
- AA. Incidence of infection 50%, mortality 95%
- BB. Incidence of infection 1 in 10,000, mortality 2%
- CC. Incidence of infection 100%, mortality 100%
- DD. Incidence of infection 1 in 10,000, mortality 90%
- EE. Incidence of infection 90%, mortality 1 in 1,000
2What are “pathogenicity islands”?
- AA. Clusters of virulence factor genes that can be transmitted by horizontal gene transfer
- BB. Groups of pathogenic bacteria bound to M cells
- CC. Patches of membrane receptors to which pathogenic bacteria bind
- DD. Plasmids on which multiple antibiotic resistance genes are located
- EE. Endemic disease foci with high prevalence of a particular disease
33. How do bacteria with Type III secretion systems (T3SS) typically enter host cells?
- AA. The T3SS pokes a hole in the host cell membrane through which the bacteria enter.
- BB. The T3SS kills the host cell, making it easier for the bacteria to enter.
- CC. The T3SS enhances binding to macrophages, which engulf the bacteria.
- DD. Effectors secreted through the T3SS cause the host cell to enfold the bacteria in membrane ruffles.
- EE. They don’t. T3SS are for secreting exotoxins, not for entering host cells.
44. Which of the following is a method for bacteria to evade the host immune defenses?
- AA. They use flagella to move from cell to cell
- BB. They have capsules to avoid phagocytosis.
- CC. They bind the C3b protein, stealing it from the host.
- DD. They block transport of iron, a major oxidant.
- EE. They bind the Fab arms of antibodies.
55. Several organisms (Staphylococcus, Pseudomonas, Enterococcus) cause disease in catheterized
patients much more frequently than in non-catheterized patients. What is the most important virulence factor for these organisms?- AAntiphagocytic capsule
- BB. Exotoxin production
- CC. Respiratory transmission
- DD. Intracellular spread via actin polymerization
- EE. Ability to form biofilms on the catheter
66. A male patient ingests a dose equal to the ID50 of E. coli that expresses the type P pilus. What
would be the most likely outcome?- APneumonia
- BDiarrhea
- CC. Urinary tract infection
- DD. An induced autoimmune disease
- EE. No infection
77. A pathogen that has evolved for a long time in the same environment as its host will exhibit which
of the following?- AA. High prevalence and high mortality
- BB. High prevalence and low mortality
- CC. Low prevalence and high mortality
- DD. Low prevalence and low mortality
- EE. High incidence and low prevalence
88. Elderly patients on long-term oral penicillin therapy often acquire the infectious disease
pseudomembranous colitis, caused by Clostridium difficile. How does penicillin use affect the course
of this disease?- AA. Penicillin kills native flora, allowing C. difficile to colonize.
- BB. Penicillin creates a “super” strain of C. difficile that is more infectious.
- CC. Penicillin triggers a hypersensitivity response in the patient.
- DD. Penicillin reduces the severity of the C. difficile infection.
- EE. Penicillin has no effect on the course of this disease.
99. Which of the mechanisms below can bacteria use to escape phagocytosis?
- AA. Enhanced motility to get away from phagocytes
- BB. Extra iron binding proteins
- CC. Production of lysins to lyse the phagocyte
- DD. Producing an IgG protease
- EE. Preventing cytokine secretion from T cells.
1010. A pathogen that has recently emerged in a particular region of the world would be expected to
have which of the following epidemiological characteristics?- AA. High virulence and low prevalence
- BB. Low infectious dose and low mortality
- CC. Low prevalence and high incidence
- DD. Low mortality and high prevalence
- EE. Balanced pathogenicity
1111. What is a major difference between an infection and an intoxication?
- AA. An infection is best treated by inducing active immunity in an ill patient.
- BB. An intoxication is best treated by passive immunization.
- CC. An intoxication usually results in disorientation and neural paralysis.
- DD. An infection is more acute than an intoxication.
- EE. The consequences of an intoxication are not as serious as those of an infection.
1212. Many pathogenic bacteria have evolved a C5a peptidase. What is the function of this virulence
factor?- AA. It reduces the host's ability to recruit phagocytes to the site of infection.
- BB. It binds host antibodies and neutralizes them.
- CC. It prevents the use of the membrane attack complex by the complement system.
- DD. It allows the bacterium to survive inside macrophages.
- EE. It creates membrane ruffles that enhance bacterial uptake by host cells.
1313. Which of the following is the best example of balanced pathogenicity?
- AA. an organism that causes acute respiratory disease that is rapidly fatal
- BB. a foodborne organism that causes septicemia
- CC. both bacteria and viruses can cause pneumonia
- DD. a virus that causes mild diarrhea and is spread fecal-oral with an ID50 of 20 organisms
- EE. a bacterium that causes an equal number of respiratory and skin diseases
1414. The picture at right shows a bacterium (arrow) entering an epithelial cell. The elaborate structure
that surrounds the bacterium forms . . .- AA. when the PAMP on the epithelial cell contacts the TLR on the bacterium.
- BB. by extension of the bacterial cell envelope
- CC. as a defense mechanism to prevent the epithelial cell from being infected
- DD. in response to a bacterial protein secreted by a Type III secretory system
- EE. as the first step in the membrane fusion process.
15Neisseria gonorrhoeae (Ng) can bind a host's C3b regulatory protein. Why does Ng do that?
- AA. to inactivate C3b when it binds to Ng
- BB. to recruit more C3b to bind to Ng
- CC. to enhance Ng's uptake into the host cell
- DD. to avoid the immune response by coating Ng with "self" antigens
- EE. That's how the body recognizes that Ng is a pathogen.
1616. What is the function of the Staphylococcal protein A?
- AA. IgA protease
- BB. Fc receptor
- CC. adhesin
- DD. prevents phagosome / lysosome fusion
- EE. activates complement C5a
1717. Which of the following would you expect to be the eventual outcome of an evolutionary selection
process in a pathogenic bacterium?- AA. Its ID50 will change gradually from 102 bacteria to 106 bacteria.
- BB. It will lose the proteins at the tips of its adhesion pili.
- CC. It will increase the size of its genome as it acquires a broad metabolic capacity.
- DD. It will change from an acute infection to a chronic one.
- EE. It will acquire the ability to kill its host much more quickly.
1818. Correctly order the following steps in the Shigella infection cycle.
- AA. M cell entry → macrophage entry → epithelial cell entry → actin polymerization
- BB. macrophage entry → actin polymerization → epithelial cell entry → bacteremia
- CC. M cell entry → actin polymerization → epithelial cell entry → macrophage entry
- DD. macrophage entry → bacteremia → toxin production → epithelial cell entry
- EE. epithelial cell entry → actin polymerization → macrophage entry → bacteremia
1919. Which of the following would typically NOT be true of an attenuated organism?
- AA. It lacks one or more pathogenicity islands.
- BB. Its ID50 is very low.
- CC. It lacks adhesion pili.
- DD. It generally causes a sub-clinical infection.
- EE. You develop a strong immune response against it.
2020. A microbiologist tells you that there is no model organism for the disease he is studying. What
does he mean by this?- AA. The structure of the disease organism is difficult to represent with a model.
- BB. There is no single organism that causes the disease.
- CC. The disease is an intoxication rather than an infection.
- DD. He will have to rely on Koch's postulates to study it.
- EE. The disease only affects humans.
2121. Which bacterial invasion and colonization (I/C) factor is correctly matched with its role in an
infection?- AA. siderophore – steals iron from the eukaryotic host
- BB. fimbriae – injected into a host cell and damage its cytoskeleton
- CC. Type III effectors – prevent uptake of bacteria by host cells
- DD. coagulase – alters the membrane structure of eukaryotic host cells
- EE. IgA protease – allows a bacterium to cause bacteremia
2222. How are bacterial type III secretion system effectors involved in causing disease?
- AA. They rearrange the host cytoskeleton and allow the bacterium to enter host cells.
- BB. They allow the bacterium to compete with the host for binding iron.
- CC. They are leukocidins that the bacterium uses to kill phagocytes.
- DD. They mimic "cancel kill" signals so NK cells don't kill infected host cells.
- EE. They bind to host cell receptors and are internalized like toxins.
2323. What are “pathogenicity islands”?
- AA. Patches of membrane receptors to which pathogenic bacteria bind
- BB. Plasmids on which multiple antibiotic resistance genes are located
- CC. Clusters of virulence factor genes that can be transmitted by horizontal gene transfer
- DD. Groups of pathogenic bacteria bound to M cells
- EE. Endemic disease foci with high prevalence of a particular disease
2424. At the right is a photomicrograph showing the bacterium Listeria monocytogenes (Lm) infecting a
human cell. What can you conclude about how this bacterium lives in its host?- ALm must have an M-protein on its surface.
- BLm grows into long, filamentous cells once it is inside its host.
- CC. After it passes through MALT tissue, Lm invades the epithelial basal membrane.
- DLm probably has an antiphagocytic capsule.
- ELm is able to use actin from its host to avoid humoral immunity.
2525. In the past 130 years we have learned quite a bit about microbes. Some things we have learned
have required us to modify the system Robert Koch developed in 1880 to identify the causative agent
of a disease. Which of the following has NOT required such a modification?- AA. The recognition that we can only culture about 1% of the bacteria we've discovered
- BB. The discovery of infections caused by biofilms involving several bacterial species
- CC. Realizing that some diseases are of an inflammatory rather than an infectious nature
- DD. Recognizing the concept of idiopathic cases of an infectious disease
- EE. The development of cell culture models to study disease processes at the cellular level
2626. What are fimbriae
- AA. Special pili with adhesive proteins at their tips
- BB. Cells in mucous membranes that uptake bacteria
- CC. A type of bacterial exotoxins
- DD. Bacterial proteins that bind iron in host blood serum
- EE. Dense polysaccharide fibers present in bacterial biofilms
2727. The genes for which of the following would be LEAST likely to be located on a pathogenicity
island?- AA. A Type III secretory system
- BB. A bacterial siderophore
- CC. A superantigen toxin
- DD. An I/C factor
- EE. LPS biosynthesis
2828. Which of the following is a mechanism that bacteria use to avoid the host's immune response?
- AA. Bacteria digest IgG
- BB. Bacteria secrete iron
- CC. Bacteria induce autoimmmune reactions
- DD. Bacteria cover themselves with antibodies
- EE. Bacteria cover themselves with C3b
2929. You are testing antibiotics in a mouse model of a new bacterial disease. You have determined the
MIC for the antibiotics from an E-test, and administered each antibiotic to several mice at greater than the MIC dose. But all the mice still die. Which of the following would be a logical conclusion from the results of this experiment?- AA. You should look for the production of a toxin by the new bacterium.
- BB. You shouldn't have used an E-test to determine the MIC of the antibiotics.
- CC. This new disease is probably polymicrobial.
- DD. You should have administered the antibiotics at a dose less than the MIC, not more.
- EE. Animal models are not valid for study of human diseases.
3030. All of the following are important for bacterial survival in a host EXCEPT the ability to . . .
- AA. digest C5a
- BB. produce siderophores
- CC. bind complement regulatory protein
- DD. induce autoimmune antibodies
- EE. produce an Fc binding protein
3131. What do the structures in these two pictures have in common?
- AA. They are both parts of the same bacterial cell.
- BB. Both involve rearrangements of the host's cytoskeletal proteins.
- CC. Both occur when a bacterial capsule is produced within a host cell.
- DD. Both are immune responses to the presence of a bacterium.
- EE. Both are ways that Shigella can enter macrophages.
- AA. They are both parts of the same bacterial cell.
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- college Microbiology Quiz on Exam 3β, created by Dustin Wagner on 08/04/2022.
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- Dustin Wagner
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