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176 Cards in this Set
- Front
- Back
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What is meant by selective toxicity?
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Chemotherapeutic agents should act against the pathogen and not the host.
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Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?
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Humans and other animal hosts lack peptidoglycan cell walls.
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Why is polymyxin only used on the skin?
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It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.
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Quinolones and fluoroquinolones act against what bacterial target?
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DNA gyrase
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Why is it difficult to find good chemotherapeutic agents against viruses?
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Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.
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If penicillin G is chosen as the best treatment for a given infection, what microorganisms are most likely the cause?
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gram-positive bacteria
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Why is methicillin-resistant Staphylococcus aureus (MRSA) methicillin resistant?
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It produces a modified version of the molecule that is targeted by the drug.
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Why is it more difficult to treat viral infections than it is to treat bacterial infections?
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Viruses use the host cell's processes to carry out their own reproduction.
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Certain cancer cells have ABC transport molecules at the cell surface. These transporters use energy from ATP to move chemotherapeutic agents out of the cell. Which of the following do you think these transporters are most closely related to?
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membrane pumps
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A researcher creates an antibiotic that binds to a protein present only on B. anthracis (the causative agent of anthrax), lysing the cell from the outside. After a couple of years using this antibiotic, some resistant organisms are found. Which of the following best outlines the mechanism for development of this resistance?
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mutation in B. anthracis → altered target → resistant bacterium
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A new bacterial molecule is discovered. This molecule binds to an antibiotic and facilitates the binding of a phosphate group, thus inactivating the antibiotic. Which category best describes the mechanism of antibiotic resistance conferred by this molecule?
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bacterial enzymes
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Which antibiotic is overcome by beta-lactamases?
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Penicillin
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How might efflux pumps increase antibiotic resistance in bacteria?
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Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.
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Bacteria that are resistant to sulfonamide have enzymes that have a greater affinity for what?
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PABA
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Why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug?
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Penicillin disrupts the cell wall, which is located outside of the cell membrane.
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Membrane transport proteins are required for which mode(s) of antibiotic resistance?
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Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.
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What is meant when a bacterium is said to become "resistant" to an antibiotic?
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The bacterium is neither killed nor inhibited by the antibiotic.
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When a patient is treated with antibiotics, __________.
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the drug will kill or inhibit the growth of all of the sensitive bacterial cells
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The process of acquiring antibiotic resistance by means of bacteriophage activity is called
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transduction.
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Which of the following mutations would not result in antibiotic resistance?
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Silent mutation
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R-plasmids can be acquired via
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horizontal gene transfer and bacterial conjugation
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Consider a Kirby-Bauer disk-diffusion assay. If you put penicillin and streptomycin disks adjacent to one another, the zone of inhibition is greater than that obtained by either disk alone. This is an example of __________.
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synergism
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What is the primary benefit of vaccination?
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An immune response will occur quicker upon future exposure to the pathogen.
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When a person has previously been vaccinated against a viral pathogen, which cells are activated if that same pathogen re-enters the host's cells months or years later?
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Memory cytotoxic T cells
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What does a vaccine contain?
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Weakened or killed pathogen or parts of a pathogen
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What is the hallmark of a conjugated vaccine?
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These vaccines contain weakly antigenic elements plus a more potent antigenic protein.
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Which type of vaccine could possibly cause a person to develop the disease?
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Attenuated live vaccine
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The influenza vaccine is an example of a(n)
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inactivated killed vaccine.
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What is the function of boosters?
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Boosters are injections that are given periodically to maintain immunity.
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The Hepatitis B vaccine is which type of vaccine?
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Subunit vaccine
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Which of the following best describes vaccination?
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An individual is exposed to a killed pathogen, an inactivated pathogen, or a component of a pathogen. The individual is protected from subsequent exposures to the pathogen because the adaptive immune system is stimulated to produce memory B cells and memory T cells, which protect from subsequent exposures.
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Which of the following is NOT an advantage of using live attenuated vaccines?
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They are usually safer than other types of vaccines.
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What is an adjuvant?
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a chemical additive that increases the effectiveness of vaccines
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I have a new test for determining whether a patient is infected with the influenza virus. It is very specific but not very sensitive. What does this mean?
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False-positives will be rare, but false-negatives may happen frequently.
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Which of the following is NOT a reason why monoclonal antibodies (Mabs) are useful?
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They are always highly sensitive.
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What is the purpose of conjugated vaccines?
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to enhance the immune response of children to polysaccharide antigens
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Western blotting is best used for which of the following?
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to detect a specific protein in a mixture
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Why is it necessary to give the HPV vaccine in multiple doses?
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Three doses of the HPV vaccine are given to elicit both a humoral and a cell-mediated response.
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The earliest vaccinations were against smallpox. Which of the following statements about the history of smallpox vaccinations is FALSE?
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Proteins from dairy cows were injected into people to protect them from smallpox.
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What is the function of myeloma cells used in the production of monoclonal antibodies?
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They are immortal cells capable of continuous growth.
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Which step in the production of monoclonal antibodies must necessarily precede all other steps in the process?
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A specific antigen is used to induce production of a specific antibody.
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Monoclonal antibodies:
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can attach to a target cell while carrying a diagnostic marker or anticellular toxin
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Which of the following statments about measles is FALSE?
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The disease has been eradicated in the United States.
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Which of the following is NOT an advantage of live attenuated vaccine agents?
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They occasionally revert to virulent forms.
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Which of the following tests is MOST useful in determining the presence of AIDS antibodies?
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indirect ELISA
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Which item is from the patient in a direct ELISA test?
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antigen
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Hepatitis B virus surface antigen can be used in a(n)
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subunit vaccine.
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Dead Bordetella pertussis can be used in a(n)
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inactivated whole-agent vaccine.
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Haemophilus capsule polysaccharide plus diphtheria toxoid is a(n)
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conjugated vaccine.
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Live polio virus can be used in a(n)
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attenuated whole-agent vaccine.
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Monoclonal antibodies are used in diagnostic tests and disease treatments because they
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are highly specific and they can be produced in large quantities.
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Inactivated tetanus toxin is a(n)
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toxoid vaccine.
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A hybridoma results from the fusion of a(an)
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B cell with a myeloma cell.
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A vaccine against HIV proteins made by vaccinia virus is a(n)
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subunit vaccine.
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Which of the following is a test to determine the presence of soluble antigens in a patient's saliva?
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precipitation reaction
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Which of the following is a test to determine a patient's blood type by mixing the patient's red blood cells with antisera?
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direct agglutination reaction
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Which of the following is a pregnancy test used to find the fetal hormone HCG in a woman's urine using anti-HCG and latex spheres?
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indirect agglutination reaction
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What type of vaccine is the live measles virus?
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attenuated whole-agent vaccine
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Purified protein from Bordetella pertussis is used in a(n)
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subunit vaccine.
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What type of vaccine involves host synthesis of viral antigens?
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nucleic acid vaccine
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Toxoid vaccines, such as the vaccines against diphtheria and tetanus, elicit a(n)
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antibody response against these bacterial toxins.
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A DNA plasmid encoding a protein antigen from West Nile virus is injected into muscle cells of a horse. This is an example of a(n)
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nucleic acid vaccine.
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An ELISA for Hepatitis C has 95 percent sensitivity and 90 percent specificity. This means that the test
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detects 95 percent of the true positive samples and has 10 percent false positive results.
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A patient shows the presence of antibodies against diphtheria toxin. Which of the following statements is FALSE?
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The patient was near someone who had the disease.
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Direct fluorescent-antibody techniques are frequently used to __________.
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detect microorganisms in a clinical sample
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Which of the following statements concerning antigen-presenting cells is true?
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They are involved in activating T cells.
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If a patient has been exposed to an antigen for the first time, which class of immunoglobulin appears first?
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IgM
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Which of the following statements concerning cellular immunity is FALSE?
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Cellular immunity involves cells that recognize antigens and make specific antibodies against them.
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An individual may be exposed to a pathogen and become infected without actually getting sick. This is known as a subclinical infection. Even in subclinical infections, the individual's adaptive immune system can generate memory for the pathogen. What type of adaptive immunity is this?
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naturally acquired active immunity
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Which of the following statements concerning immunological memory is true?
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The memory response is due to production of long-lived cells that can respond very rapidly upon second exposure.
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ADCC is a process that is most effective in destroying
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eukaryotic pathogens.
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An antibody's Fc region can be bound by
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macrophages.
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Cytokines released by TH1 cells
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activate CD8+ cells to CTLs.
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Which of the following destroys virus-infected cells?
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CTL
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The presence of which of the following indicates a current infection rather than a previous infection or vaccination?
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IgM
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In the figure, what can attach to a host cell?
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e
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In the figure, which areas represent antigen-binding sites?
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a and b
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In the figure, which areas are different for all IgM antibodies?
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a and b
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In the figure, which areas are similar for all IgG antibodies?
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c and d
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Which of the following is the best definition of antigen?
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a chemical that elicits an antibody response and can combine with these antibodies
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Which of the following statements is FALSE?
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The constant region of a heavy chain is the same for all antibodies.
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The most abundant class of antibodies in serum is
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IgG
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Large antibodies that agglutinate antigens are
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IgM
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In addition to IgG, the antibodies that can fix complement are
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IgM
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The antibodies that can bind to large parasites are
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IgE
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The antibodies found on the surface of B cells, and which always exist as monomers, are
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IgD
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The antibodies found in mucus, saliva, and tears are
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IgA
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Plasma cells are activated by a(n)
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antigen
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Which of the following is NOT a characteristic of B cells?
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They recognize antigens associated with MHC I.
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The specificity of an antibody is due to
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the variable portions of the H and L chains.
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Which of the following statements is NOT a possible outcome of antigen-antibody reaction?
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clonal deletion
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Newborns' immunity due to the transfer of antibodies across the placenta is an example of
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naturally acquired passive immunity.
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Which of the following is the best definition of epitope?
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specific regions on antigens that interact with antibodies
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What type of immunity results from recovery from mumps?
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naturally acquired active immunity
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What type of immunity results from transfer of antibodies from one individual to a susceptible individual by means of injection?
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artificially acquired passive immunity
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What type of immunity results from vaccination?
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artificially acquired active immunity
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Consider a helminthic infection in which an individual is colonized by a parasitic worm. The worm is too big to be engulfed by a phagocytic cell. How does the immune system respond?
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The worm gets coated with antibodies, which activate other cells in the immune system to secrete chemicals that kill it.
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If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers (as opposed to a blood smear from a normal patient NOT infected with worms)?
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eosinophils
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Which of the complement pathways employs properdin?
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Alternative pathway
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In the classical pathway, which of the following directly activates cellular responses?
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C3a, C5a, and C5bC6C7
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Antibodies from cellular immune responses are used in
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the classical pathway.
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Which of the complement pathways was discovered first?
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The classical pathway
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Which of the following are functions of lectins?
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They act as opsonins for phagocytosis, they attach to carbohydrates on some bacterial and viral surfaces, and they activate C2 and C4.
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How does cytolysis occur via the complement pathway?
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Formation of the MAC in invading cells, killing them
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Which complement protein is used as an opsonin?
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C3b
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If a person lacked the ability to form C5, what result of complement could not occur?
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Cytolysis
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If a person could not form C2, which result of complement would be affected?
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Cytolysis, chemotaxis, inflammation, and opsonization
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What complement result involves the use of phagocytes?
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Chemotaxis and opsonization
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Which of the following is an event that ultimately results in activation of complement C3 by splitting it into C3a and C3b?
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interaction of mannose-binding lectin with mannose molecules on a bacterium
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________________ is/are always present in an individual's blood. However, in the absence of infection, it is in an inactive form.
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Kinins
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You note that the body temperature of one of your patients is starting to increase. As a result, you can infer that all of the following may be occurring in this patient EXCEPT __________.
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dilation of blood vessels
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Which statement regarding the lymphatic system is true?
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Lymphatic capillaries possess one-way valves. These valves permit the uptake of fluid from the body but do not allow the fluid to flow back out of the capillaries into the intracellular spaces.
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A response that is uniquely directed against pathogenic Bordetella pertussis would involve what component?
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Antibodies
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First line defenses have what aspect in common with each other?
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They are physical barriers against invading pathogens.
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Both the innate and adaptive defenses of the immune system work to prevent
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the penetration and colonization by pathogens, and the diseases they cause.
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If a new bacterial pathogen entered a human body through an accidental needle stick, the first cell that would try to kill the pathogen would likely be
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a phagocyte.
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Which non-specific defense mechanism is mismatched with its associated body structure or body fluid?
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mucociliary escalator intestines
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Lysozyme and the antibiotic penicillin have similar mechanisms of action in that they both cause damage to the bacterial
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cell wall.
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All of the following pertain to fever EXCEPT that it
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accelerates microbial growth by increasing iron absorption from the digestive tract.
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All of the following are true regarding NK cells EXCEPT
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they destroy infected body cells by phagocytosis.
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Activation of C5–C9 results in
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lysis of microbial cells.
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What cellular macromolecules make up the complement pathway?
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proteins
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Based on the animation, which of the following is cleaved by C1?
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C2 and C4
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Where are the complement proteins found in the body?
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the blood serum
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Based on the animation, which of the following is responsible for cleaving C3?
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C2aC4b
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Based on the animation, which of the complement proteins can directly bind to the surface of a bacterial cell?
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C3b
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Which of the following statements about the classical pathway of complement activation is FALSE?
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C3 is not involved in the classical pathway.
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All of the following are components of the inflammatory process EXCEPT
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antibody synthesis.
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The lectin pathway for complement action is initiated by
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mannose on the surface of microbes.
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All of the following occur during inflammation. What is the first step?
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vasodilation
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Innate immunity includes all of the following EXCEPT
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production of antibody.
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The classical pathway for complement activation is initiated by
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antigen–antibody reactions.
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The alternative pathway for complement activation is initiated by
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lipid-carbohydrate complexes and C3.
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All of the following are part of the mechanism of action of alpha and beta interferons EXCEPT
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they are effective for long periods.
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All of the following are effects of histamine EXCEPT
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production of antibodies.
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Phagocytes utilize all of the following to optimize interaction with microorganisms EXCEPT
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lysozyme.
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Each of the following provides protection from phagocytic digestion EXCEPT
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formation of phagolysosomes.
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Normal microbiota provide protection from infection in each of the following ways EXCEPT
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they produce lysozyme.
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Each of the following is an effect of complement activation EXCEPT
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interference with viral replication.
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A child falls and suffers a deep cut on her leg. The cut went through her skin and she is bleeding. Which of the following defense mechanisms will participate in eliminating contaminating microbes?
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phagocytosis in the inflammatory response
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The function of the "ciliary escalator" is to
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trap inhaled dust and microorganisms in mucous and propel it away from the lower respiratory tract.
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All of the following protect the skin and mucous membranes from infection EXCEPT
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HCl
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Innate immunity
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is nonspecific and present at birth.
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Which of the following statements about beta interferon is true?
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It acts as a signal that induces uninfected cells to produce antiviral proteins.
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Which of the following statements about innate immunity is true?
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Innate immunity is present at birth.
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An inflammatory response would result from which of the following?
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Jellyfish sting
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If a person turns their ankle, how would one determine if damage to the tissue in the ankle has occurred?
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The ankle is red, swollen, and warm to the touch.
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What is the function of inflammation in response to a burn from a hot iron?
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To repair the damaged tissue
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In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true?
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Shiga toxin is more lethal than staphylococcal enterotoxin.
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Which of the following would be an example of an infection initiated via the parenteral route?
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An individual contracts hepatitis B from an accidental stick with a contaminated needle.
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Which statement regarding endotoxins is true?
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One consequence of endotoxins is the activation of blood-clotting proteins.
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In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used?
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to ensure that a sterilized medical device is free of endotoxin
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Which of the following statements about adherence is true?
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Most bacterial adhesins are glycoproteins or lipoproteins.
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Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage?
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cholera
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Patients developed inflammation a few hours following eye surgery. Instruments and solutions were sterile, and the Limulus assay was positive. The patients inflammation was due to
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endotoxin.
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Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by
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transduction.
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Which organism in the table causes the most severe disease?
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It cannot be determined from the information provided.
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Which organism in the table most easily causes an infection?
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Legionella pneumophila
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the table shows the ID50 for Staphylococcus aureus in wounds with and without the administration of ampicillin before surgery. Based on the data, the administration of ampicillin before surgery
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decreases the risk of staphylococcal infection.
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Antibiotics can lead to septic shock if used to treat
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gram-negative bacterial infections.
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Endotoxins in sterile injectable drugs could cause
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septic shock symptoms.
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Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed,
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polypeptide B would not be able to enter the cells.
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All of the following bacteria release endotoxin EXCEPT
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Clostridium botulinum.
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Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?
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mucous membranes only
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Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to
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superantigens.
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Twenty-five people developed symptoms of nausea, vomiting, and diarrhea three to six hours after attending a church picnic where they ate a ham and green bean casserole with cream sauce. The most likely cause of this case of food intoxication is
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erythrogenic toxin.
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Which of the following contributes to the virulence of a pathogen?
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numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production
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All of the following are used by bacteria to attach to host cells EXCEPT
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A-B toxins.
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All of the following organisms produce exotoxins EXCEPT
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Salmonella typhi.
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Superantigens produce intense immune responses by stimulating lymphocytes to produce
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cytokines.
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All of the following are examples of entry via the parenteral route EXCEPT
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hair follicle.
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Which of the following is NOT a membrane-disrupting toxin?
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A-B toxin
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Endotoxins are
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part of the gram-negative cell wall.
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Which of the following statements about exotoxins is generally FALSE?
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They are resistant to heat.
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All of the following contribute to a pathogens invasiveness EXCEPT
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toxins.
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The ID50 is
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the dose that will cause an infection in 50 percent of the test population.
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