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Microbiology Exam 4 Questions (16-19)
Terms in this set (271)
Following exposure to a pathogen, antibodies are produced as a part of the adaptive immune response. Place the steps of this response in the order that they generally occur.
1. Pathogens enter the body
2. Antigen-presenting cell engulfs the pathogen
3. Antigen-presenting cell presents antigen to helper T cell
4. Helper T cell becomes activated
5. Helper T cell activates B cell which has previously bound the same antigen
6. B cell clonally expands
7. Plasma B cells produce antibody
Which is most likely to be a potential antigen?
a bacterial exotoxin
Each B cell is capable of recognizing and producing antibody to multiple antigens of a single pathogen
Match the cell type to its description
kills infected host cells displaying antigen: cytotoxic T cell
activates other adaptive immune cells: helper T cell
produces and secretes antibodies: plasma B cell
rapidly produces new antibody-secreting cells following re-exposure to antigen: memory B cell
Which of the following statements regarding adaptive immunity are true?
Antigens elicit the formation of specific antibodies.
Microbial pathogens are composed of many antigens.
Antigenicity of an epitope is dependent on its shape. Denaturing proteins generally removes the conformational epitope.
Which of the following is an example of a hapten?
What term describes the degree of immune-response induction that an antigen can produce?
Though each antibody is specific to one antigen, highly similar antigens may be recognized by the same antibody. Because of this, some foreign antigens that resemble self antigens are "ignored" by the immune system in order to prevent damage to the body's own cells.
Which is an example of cross-protection?
antibodies to cowpox can provide some protection against smallpox
IgG is able to bind to antigens on the surface of a pathogen. Once bound, the Fc region of the antibody is exposed and can interact with phagocytes, increasing the likelihood the pathogen will be engulfed and destroyed. What term describes the process of IgG binding to the pathogen?
Match the characteristic to the class of antibody with which it is primarily associated. More than one characteristic may be associated with an antibody class.
IgM: commonly found as five monomers joined by a J-chain.
first antibody produced in the initial adaptive immune response
IgG: transmitted across the placenta from mother to fetus.
most abundant antibody in blood
IgE: associated with the degranulation of mast cells and allergy
IgA: commonly found as a dimer
secreted across mucosal surfaces
IgD: found at low levels in blood but is abundant on the surface of B cells
Mothers can naturally, passively provide protection against pathogens to their infants by giving them pre-formed antibodies that are able to prevent some pathogens from adhering to the infant's intestinal cells and infecting. Which antibody type would be associated with this protection?
The constant region of antibodies' heavy chains has the same amino acid sequence in all classes of immunoglobulin.
A single B cell has approximately 50,000 B-cell receptors. How many distinct epitopes is this cell capable of recognizing?
Isotype switching occurs only from IgM to IgG.
Which steps contribute to the generation of antibody diversity?
rearrangement of genes in the genomes of B cells
generation of different codons
What term describes the strength of the binding between an antibody and its epitope?
T-cell-independent activation of B cells is associated with which of the following?
capping or cross-linking of multiple B cell receptors
A primary antibody response is initiated following exposure to a pathogen for the first time. Order the primary antibody response below.
1. Foreign antigen binds B cell with appropriate antibody
2. B cells become activated and differentiate into plasma and memory cell
3. Low-affinity IgM is produced and secreted into serum
4. Isotype switching occurs
5. Large quantities of IgG are produced and secreted into serum
6. Plasma cell dies
Which are true of regulatory T cells?
inhibit T cells that should have been eliminated in the thymus but were not
Associate the following items with either major histocompatibility complex class I or major histocompatibility complex class II.
presents antigen produced within APCs
recognized by CD8 T cells
found on all nucleated body cells
presents antigen phagocytosed by APCs
found only on APCs (dendritic, macrophage, and B cell)
recognized by CD4 T cells
T cells must be educated in the thymus to avoid damaging self-recognition. In this process, what is the fate of T cells that weakly recognize self MHC?
these cells leave the thymus and move to secondary lymphoid tissues
T cells are subdivided into many types, each of which has a particular function in the response to a pathogen. Match the T-cell type to its primary role.
B-cell activation: TH2
activate cytotoxic T cells: TH1
destroy infected or cancerous body cells: TC
Memory B cells require an activation signal in addition to specific antigen binding in order to produce new plasma cells. What is the second, activating signal?
secreted IL-4 and IL-6 from activated helper T cells
Activation of a TH0 cell requires which of the following?
recognition of specific antigen by TCR
APC presentation of antigen on MHC II
CD28 binding to B7 on the surface of an APC
Suppose that a B cell is activated by two signals. The first signal is capping. The second signal is a TLR on the B cell interacting with a PAMP. Given these two signals, the B cell will produce only IgM and no further class switching will occur.
How are T-cell receptors similar to B-cell receptors?
both bind specific antigens
A cytotoxic T cell with a TCR specific to virus X antigen is present in a person infected with virus X. What must occur for the cytotoxic T cell to help resolve the infection in this person? Place the steps in the correct order.
1. An APC from an infected site presents virus X antigen on MHC 1
2. Tc cell CD8 binds MHC I and the TCR binds virus X antigen
3. Tc cell receives IL-2 from activated TH1 cell
4. Tc cell is activated
5. Tc cell travels to site of infection
The killing of infected cells by cytotoxic T cells resembles the process of killing by natural killer cells. How do the two processes differ?
NK cells do not recognize specific antigen
Killing of infected cells by cytotoxic T cells is beneficial and not harmful to the host.
Which of these techniques might microbes use to successfully evade an immune response mounted against them?
inhibit production of pro-inflammatory cytokines
trigger apoptosis of immune cells
induce production of anti-inflammatory cytokines
Release of cytokines from immune cells stimulates other cells to release these molecules as well, which can lead to an over-amplification of these signals known as a cytokine storm. Some proteins (including known bacterial toxins) can trigger this response by directly binding to the outside of T-cell receptors without being recognized or processed as antigens. What is the name of these proteins?
Which of the following cell types would be considered "professional APCs" (antigen-presenting cells)?
The body's immune response to a microbe is really multiple responses to multiple small regions of that microbe. Each small region that is recognized by a specific component of the immune system is referred to as what?
Put the following types of organic molecules in order from the most antigenic (immunogenic) to the least antigenic.
small inorganic molecules (ex: drugs)
Most of the proteins found in our bodies are proteins that are made by our own cells. Why don't T cells activate in response to self-antigens?
T cells that bind to MHC molecules containing self-antigens are killed in the thymus during T-cell education.
In the secondary response, the IgG levels rise much faster than they did during the first antibody response. Why is this?
Memory B cells are present for the secondary response. Those cells are much easier to activate than the naive B cells; therefore, the response occurs much more quickly and on a larger scale.
Some viruses have the ability to evade the immune system by blocking the cell's ability to display antigens in MHC class I receptors. How would the loss of MHC class I receptors affect the immune system's response?
It would prevent cytotoxic T cells from recognizing the cell as infected.
Which of the following statements describes two antibodies that would be allotypes?
Two IgA antibodies against the same microbe that were made by two different plasma cells in two different people
Which of the cell types from the list below would NOT express MHC class I receptors?
Red blood cells
What do granzymes do?
Granzymes stimulate cell death in infected cells.
Superantigens are able to bind to two different receptor proteins at the same time and cross-link them. Which two molecules does a superantigen bind to?
A T-cell receptor and an MHC class II receptor
What is the result of a superantigen cross-linking these receptors?
It can cause the T cell to become activated without binding to antigen.
What is a cytokine?
A small signaling peptide
The virus particle is coated in antibodies, but underneath those antibodies is still a viable pathogen. Why do we NOT have to worry about this virus infecting our cells anymore?
The antibodies cover the parts of the virus that allow it to bind to cells, so it can no longer get into a host cell and replicate.
Why will these antibodies NOT protect us the next time we get a cold (are exposed to a rhinovirus)?
Viruses mutate quickly, so the next virus will have slightly different epitopes and the same antibodies will not be able to bind to them.
A small segment of any antigen that can elicit an immune response is called a(n) _____
Which of the following secretes antibodies during an immune response?
Which cell type is most directly responsible for coordinating humoral and cellular immune responses to an infection?
All "professional" antigen-presenting cells _____
present antigen on MHC surface receptors
Which of the following are the most effective immunogens?
An antibody that binds only a specific, single structure is an example of _____
Idiotypic sequences are found in which part of the structure shown in the previous question?
Two antibody class molecules, IgG and IgM, that recognize the same epitope and are from the same person differ from each other in their _____
heavy-chain constant regions
Which class of antibody has a form secreted across mucosal tissues of the intestine or lung?
All immunoglobulin-family proteins are antibodies. True or false?
Which of the following antibody isotypes is predominantly made following a secondary exposure to an antigen (a pathogen, for instance)
B-cell receptors have which of the following as their primary component?
IgM or IgD
Clonal selection occurs when _____
B cell proliferate to produce new B cells with identical B-cell receptor surface proteins
Memory B cells undergo which of the following processes?
affinity maturation of antigen-binding site
The following cells participate most directly in adaptive cell-mediated immunity
activated CD8 T cells
A patient whose antigen-presenting cells lack the protein called the transporter of antigen peptides will be defective in the _____
generation of cytotoxic T cells
To function properly, all T cells must _____
bind weakly to some self-antigen
MHC II complexes on antigen-presenting cells are loaded with _____ produced peptides
In addition, to T-cell receptor complexes, T cells must express surface marker _____ in order to selectively recognize an MHC class II-antigen complex on antigen-presenting cells
What happens in a person who lacks CD40 ligand on his or her T cells?
inability to undergo isotype switching
Gene rearrangement to form the antigen-binding site (VDJ)
B-cell activation by APCs
T-cell help for B cells
Which of the following cell types are needed to activate CD8 T cells?
Cytotoxic T cells target infected cells that present antigen on _____
MHC I receptors
To activate T cells, superantigens must _____
bind T-cell receptors and MHC outside of their antigen-binding regions
Cytomegalovirus, which can cause a mononucleosis-type disease, prevents the immune system from destroying infected cells by _____
placing a molecular mimic of MHC I on an infected cell surface
Match each clinical example to the deficient immune component.
complement: C3 deficiency
B cells: hyper IgM syndrome
phagocytes: chronic granulomatous disease
severe combined immunodeficiency (SCID)
Why is MHC II deficiency (bare lymphocyte syndrome) considered a T-cell disorder?
without antigen presentation, TH0 cells cannot be induced to form other types of T cells
More than 200 separate primary immunodeficiencies are known, with B-cell defects being the most common subtype.
Which are true of complement system deficiencies?
Patients with complement defects may be treated with complement-containing plasma.
Complement-deficient patients have normal T-cell responses.
Complement-deficient patients should receive normal vaccinations.
The exact chromosomal locations of all primary immunodeficiencies are known. For example, chronic granulomatous disease is caused by a defect in the CYBB gene.
You are examining a patient's results from serum electrophoresis and note that the gamma-globulin band is abnormally narrow, indicating the overproduction of a monoclonal antibody. This result would likely lead you to consider a diagnosis of which type of neoplasm?
The deposition of clumps of secreted antibody light chains in organs, particularly the kidney, can cause damage. What are these clumps of secreted antibody light chains called?
This highly survivable cancer is characterized by groups of multinucleated, B-cell-derived Reed-Sternberg cells and often occurs following certain viral infections.
The absence of some immune components, or defects in those components, increases a person's chances of infection and cancer.
Epstein-Barr virus (EBV) is associated with which of these immune disorders?
infection of B cells leading to neoplasms
Which of the following are B-cell neoplasms?
A B cell that is matched to a low-affinity antigen has lost the ability to undergo apoptosis.
A cell proliferation gene is expressed at the same rate as an immunoglobulin gene.
Match the term to its defining feature
single-site plasma cell neoplasm: plasmacytoma
solid tumor in lymphoid tissue: lymphoma
malignant lymphoid cells in circulation or bone marrow: leukemia
plasma cell neoplasms with several locations: multiple myeloma
When mast cells degranulate, they can release a compound that mediates allergic symptoms. This compound binds to receptors on multiple cell types, leading to itching, smooth muscle contraction, and increased vascular permeability. What is this compound?
What is true of type IV hypersensitivity reactions?
it includes contact dermatitis
Pieces of evidence that support the hygiene hypothesis include which of the following?
Reducing gut flora in young children is associated with asthma.
Bacterial infections that increase TH1 responses may inhibit IgE formation.
What is the name for an antigen that causes the immune system to react more strongly than is warranted by the antigen itself, or that mimics host structures?
A patient with A, Rh- blood needs a transfusion. Which of the following blood types can be used without risk of a type II hypersensitivity response?
Hemolytic disease of the newborn can result under these conditions.
Rh- mother/Rh+ fetus, second pregnancy
Individuals with a genetic predisposition to allergy commonly experience an anaphylactic reaction to bee stings the first time they are stung.
In commonly administered TB skin tests, a small amount of antigen associated with the Gram-positive bacillus that causes tuberculosis is injected under the skin. Approximately 48 hours later, the person is examined for the occurrence of a type IV hypersensitivity reaction at the injection site. A positive result would indicate that the person has a current tuberculosis infection.
Which statements accurately describe the treatment of a type I (anaphylactic) hypersensitivity response?
IgE may be neutralized prior to mast cell binding, preventing sensitization.
Benadryl mimics histamine, competing for binding sites.
Inhaled steroids minimize inflammation
IgG antibodies may be induced to neutralize antigens before those antigens can bind mast cells.
Match prominent characteristics to the hypersensitivity type with which they are associated.
allergen-displaying host cells killed by complement
time of onset more than 24 hours postexposure
allergen-displaying host cells killed by TC cells
Place the given steps in order to create the natural course of type I hypersensitivity to cat dander.
1. Person encounters cat for the first time
2. B cell with high-affinity match to dander is activated by T helper cell
3. Large amounts of cat dander-specific IgE are produced and bind mast cells
4. Person encounters cat a second time
5. Cat dander binds to multiple mast-cell-bound IgE, causing degranulation
6. Person experiences symptoms such as sneezing and itching
A patient with type B, Rh+ blood is concerned about hemolytic disease in her newborn because her husband has type AB, Rh+ blood and her first child had type A, Rh+ blood. Her concerns are warranted because anti-A antibodies can cross the placenta.
How may autoimmunity be induced?
Microbial antigen similar to self-antigen is presented
Self-reactive B cells are activated without a self-reactive specific T cell.
Which best describes the mechanism of transplant rejection?
host T cells react to foreign MHC molecules
The autoimmune process involved in systemic lupus erythematosus, in which antibodies and antigens interact to form clusters that may be deposited in tissue, is similar to which type of allergic reaction?
type III hypersensitivity
Autoimmune diseases can be correctly thought of as hypersensitivity reactions that occur in response to self, rather than foreign, antigens.
Match the common approved vaccine to its type.
How can DNA vaccines be described?
a method of producing antigen presentation similar to natural infection
nucleic acid sequences placed directly into muscle cells
Immunocompromised patients should not be given live attenuated vaccines. For this reason, it is very important that healthy people are vaccinated, as this reduces the spread of those preventable diseases.
About 90% of the US population is vaccinated against the measles virus, which leaves approximately 31 million unvaccinated individuals. The rate of infection in those 31 million people, however, is not the normal background rate but is instead much lower, because transmission does not occur through the vaccinated population. What is this phenomenon called?
Agglutination and precipitation are based on the same basic cross-linking principle, but whereas precipitation measures small (A) _____ antigens , agglutination measures insoluble antigens on (B) _____ _____.
soluble; whole cells
An individual who has had tuberculosis in the past will have _____ _ _____ that can recognize the antigens. These cells will release a variety of cytokines that call polymorphonuclear leukocyte (PMN) cells to the site, leading to a large red welt on the patient's skin within 24 to 48 hours.
memory T cells
When the immune system overreacts to a foreign antigen, it is called an allergic hypersensitivity reaction, and the antigen causing the reaction is called a(n) _____
Plasma cells can become malignant. What is neoplasmic growth of a plasma cell at a single site called?
Which of the following autoimmune diseases occurs when an autoantibody is made that binds to the thyroid-stimulating hormone (TSH) receptor present on thyroid gland cells?
Which type of vaccine physically links a highly immunogenic protein with a poorly immunogenic capsule polysaccharide to boost the immune reaction to the polysaccharide?
Which of the following is/are types of passive immunization?
Injection of antitoxins (antibodies that inactivate microbial toxins)
Injection of immune globulin
Transplanting organs from a donor with one type of MHC protein into a recipient with a different type of MHC is called what?
The M protein of Streptococcus pyogenes can damage cardiac tissue and result in an autoimmune disease called rheumatic fever. The similarity between the epitope in M protein and cardiac tissue is an example of which of the following?
B-cell defects causing antibody deficiencies are the most common type of _____ immunodeficiencies, which have a genetic basis and usually manifest in early childhood.
Severe combined immunodeficiencies (SCIDs) are characterized by a lack of which of the following?
The ability to distinguish between self antigens and foreign antigens is crucial to our survival; without this ability, our immune system would constantly attack us from within. Self-attack doesn't normally happen because the body develops which of the following?
tolerance to self
Herd immunity occurs when a large portion of a population is immunized. Because the _____ individuals in the "herd," or community, will not become infected, they cannot spread the disease to others.
Which of the following is/are features of an effective vaccine?
It should not harm the person being vaccinated.
It should stimulate B-cell (antibody) and T-cell (cell-mediated) responses.
It should produce long-term memory.
Human immunodeficiency virus causes
a secondary immunodeficiency
The most common form of severe combined immunodeficiency is due to
lack of IL-2 receptor
A 1-month-old child with a low white blood cell count, low-set ears, cleft palate, and underdeveloped thymus will most likely have which one of the following?
Treatment of patients with X-linked agammaglobulinemia includes which one of the following?
IV administration of immune globulin
A solid mass in a lymphoid organ is called a
Infection with Epstein-Barr virus is linked to
The process by which lymphocytes scan for cancerous cell growth is called
Which of the following hypersensitivity reactions is antibody-independent?
Epinephrine stops anaphylaxis by which of the following means?
Increasing cAMP production to stop mast cell degranulation
Relaxing smooth muscle around bronchioles
Patient injected with antiserum made from horse blood; 12 days later, patient develops fever, urticarial rash, and joint pains
type III hypersensitvity
Mouse A has an allergy to a chemical placed on its skin; mouse B does not. However, when mouse B is transfused with white blood cells from mouse A, mouse B now becomes allergic to the same chemical
type IV hypersensitivity
A 5-year-old boy with type A blood was in a serious car accident and required a transfusion. Mistakenly he received type AB blood. Within hours he was experiencing chills, his blood pressure dropped, and his urine was tinged red
type II hypersensitivity
Autoantibodies are formed when _____
molecular mimicry enables a mismatched TH cell to activate a B cell that escaped deletion
The pathophysiology of Grave's disease involves _____
antibody that targets thyroid-stimulating hormone receptor
Why can type A red blood cells be transplanted (transfused) between allogenic individuals?
absence of MHC type I complexes on red blood cells
Which of the following is an example of passive immunization?
The best protection against a second infection by a pathogen is which of the following?
The concept whereby unvaccinated persons are protected from infection by those vaccinated in the community is called ______
Place the steps of pathogenesis in order following initial contact between the host and the microbe.
1. tissue attachment
3. immune avoidance
4. host damage (disease)
5. pathogen exit to next host
Genes that encode features that increase the virulence or pathogenicity of an organism can usually be found in which genetic elements?
Which is NOT true of genomic islands?
All genomic islands contain virulence-associated genes
Streptococcus agalactiae (group B streptococcus) encodes a diarrhea-producing labile toxin from Escherichia coli that was transferred by a phage.
This term (plural) refers to the specific features that distinguish pathogenic strains or species from their nonpathogenic counterparts. These include toxins, adhesins, and immune evasion mechanisms, among others.
Which virulence factor is associated with the progression of disease after colonization by Neisseria meningitidis?
PptB, an enzyme that reduces aggregation
Which are true bacterial adhesion factors?
type I pili
nonpilus adhesins (e.g., intimin)
type IV pili
This general term describes any factor that promotes bacterial attachment. Most are proteins of one form or another.
Bacteria in most environments form this type of microbial community, which is now the most serious and costly type of health care-associated infection.
Regardless of the disease, infectious pathogens must be able to attach in order to cause illness.
Which toxin/action pair is NOT properly matched?
The symptoms of diphtheria can be treated with antibiotics.
Superantigens are the exotoxin type most likely to be associated with fever, and they can act without being processed by antigen-presenting cells.
Regardless of the organism that produces it, endotoxin is always the lipid A component of this outer membrane component.
Match each description to the type of toxin with which it is associated.
produced by some Gram-positive and some Gram-negative bacteria
deliberately released as virulence factors
many diverse mechanisms of action
produced by all Gram-negative bacteria
Match the specific AB toxin or toxin component to the genus that produces it.
Vibrio: cholera toxin
Escherichia: labile toxin
Corynebacterium: diphtheria toxin
Bordetella: pertussis toxin
Describe the action mechanism of labile toxin by placing the steps in the correct order.
1. Bacterium attaches to intestinal epithelium
2. B subunits bind carbohydrate surface structures
3. A subunit enters an epithelial cell via endocytosis
4. A subunit causes an increase in cellular cAMP
5. High cAMP levels cause secretion of Cl- into intestinal lumen
6. Water enters intestinal lumen (diarrhea)
Why would patients with excess free iron in the blood be more susceptible to hemolytic uremic syndrome (HUS)?
iron upregulates the expression of Shiga toxin
A patient is having a response to the release of endotoxin after antibiotic treatment for Gram-negative sepsis. Which are likely consequences of this toxin release?
activation of clotting factors
Bacteria producing which toxin could be identified after growth on a blood agar plate?
Which of the following is the main function of the staphylococcal virulence factor "protein A"?
binds Fc region of antibodies, turning variable regions away from bacterium
binds Fc region of antibodies, preventing phagocyte binding
Organisms can survive within immune cells after phagocytosis if they can escape the phagosome or prevent fusion with the lysosome, but they will be killed if the lysosome is permitted to fuse.
When many bacteria accumulate, levels of this secreted chemical rise to a level that causes the bacteria to begin to produce virulence factors.
Which are true of the relationship between bacterial capsules and the immune system?
Antibodies can be formed to the bacterial capsule.
Bacterial capsules form the repeating subunit component of conjugated vaccines.
Capsules obscure normal phagocyte binding sites
Shigella and Listeria do not possess working flagella at human body temperature but are known to be motile within host cells. How do they accomplish movement within and between cells?
Assign each feature to the virus with which it is associated.
fatality rate of up to 4%
hemagglutinin required for cell entry
attaches to host receptor ICAM-1 using VP1
Which are true of human papillomavirus (HPV) infection?
HPV can cause warts.
HPV can cause penile cancer.
A vaccine is available that prevents several cervical cancer-associated HPV strains.
Unneeded proteins in human cells can be selectively tagged for degradation by this process.
Which is a role played by Nef in HIV infection?
prevents T-cell apoptosis
Bacteria, viruses, and parasites are all capable of immune evasion by antigenic variation.
Which are true of the relationship between parasites and the immune system?
Many parasitic mechanisms of immune evasion are similar to those of bacteria.
Intracellular parasites may suppress cell-mediated immunity.
Most tissue damage associated with parasitic infection is caused by the reaction of the immune system.
Which best describes the term "antigenic masking"?
use of host cells antigens to cover pathogenic antigens
Toxoplasma parasites may be surviving within the host cells of up to one-fifth of Americans.
Which of the following HIV proteins protects the infected cell from being killed by CD8 cytotoxic T cells by downregulating CD4 and MHC class I proteins?
Nef (negative factor)
Which of the following bacteria uses lipoteichoic acid as an adhesion to attach to the buccal epithelium?
Which of the following methods do protozoans use to invade host cells?
Order the steps to show how Toxoplasma gains entry into host cells.
1. Toxoplasma approaching a host cell membrane uses MIC proteins to attach
2. The myosin motor propels the organism through the membrane without the cell forming a phagocytic vacuole
3. A protease located at the parasite's posterior cleaves the adhesin and allows interalization
Altering the pattern of host _____ production is one way parasites like Plasmodium can actively suppress the immune response to their presence.
Random mutations caused by the error-prone viral RNA polymerase of the influenza virus can cause minor changes in hemagglutinin antigen structure, in a process called
Why does endocytosis, followed by formation of the phagosome, allow temporary safe harbor for pathogens?
Antibodies and phagocytic cells will not penetrate live host cells.
Scientists have shown that different Streptococcus agalactiae strains exchange large portions of their chromosome via _____ elements located at different positions around the chromosome.
Invading pathogens need attachment mechanisms to stay put. Which of the following is NOT a method that the human body uses to expel pathogens?
Blood is continuously circulated through the body to remove pathogens from sensitive tissues.
Which of the following is part of the lipopolysaccharide (LPS) that forms the outer leaflet of the Gram-negative outer membrane?
Staphylococcus aureus has a cell wall protein called protein A that binds to the Fc region of antibodies, hiding the bacteria from which type of immune cell?
Which of the following represent(s) unique characteristics of biofilms?
Within a single biofilm, we can find localized differences in the expression of surface molecules, antibiotic resistance, nutrient use, and virulence factors.
Bacteria in biofilms coordinate their behavior through cell-cell communication using secreted chemical signals, which is called quorum sensing.
Which of the following applies to latent herpes virus DNA?
It produces several small RNA molecules called microRNAs.
Staphylococcus aureus, an organism that causes boils and blood infections, produces a hemolysin called
Which of the following mechanisms contributes directly to pathogen evolution?
Bacteria lacking pili cannot attach to host cells. True or false?
Twitching motility is carried out by _____
type IV pili
Chronic infections are usually associated with _____
_____ pili continually assemble and disassemble
Bordetella pertactin is an example of a(n) _____
Pilus contact between a pathogen and a host cell _____
prevents evacuation of the pathogen
Which of the following toxins does calmodulin activate?
Anthrax EF toxin
Which of the following toxins ADP-ribosylates a G-factor?
E. coli LT
The following toxin stimulates cytokine production through a superantigen mechanism:
toxic shock syndrome toxin
Endotoxin is associated with _____
Type III secretion systems are paralogous to
flagellum synthesis systems
Type II secretion systems _____
secrete proteins into the surrounding environment
Salmonella enterica, while causing an infection _____
remains in the hose cell phagosome
Which of the following bacteria is an obligate intracellular pathogen?
Listeria monocytogenes _____
moves intracellulary via actin tails
Which of the following strategies helps a pathogen avoid the immune system?
delay synthesis of virulence factors until a certain bacterial cell number is reached
Which of the following best explains why one person can develop multiple colds over a lifetime?
multiple rhinovirus strains that possess different VP1 structures
HIV glycoprotein 120
HIV Tat protein
accelerates HIV transcription
HPV E7 protein
stimulate(s) host cell division
Matching the following organisms to the method of entry into host cells
Toxoplasma: actin-myosin motor
Leishmania: phagocytic cell receptors
Half the world's population suffers from the disease toxoplasmosis. True or false?
Trypanosomes avoid the immune system by varying their surface antigens. True or false?
By which of the following mechanisms do Leishmania protozoans aviod the immune system?
downregulate IL-12 production to infected macrophages
Match the disease to the type of rash it causes.
vesicular or pustular:
Fungal skin diseases are named according to their causative agent.
Please place the layers of skin in order from the most surficial to the deepest.
1. stratum corneum
2. stratum lucidum
3. stratum granulosm
4. stratum spinosum
5. stratum basale
Which of the following can be found in the dermis?
What do we call the star-shaped, macrophage-like cells that are in the epidermis, above the basal layer?
Eye infections are always considered serious infections.
Which of the statements are true of the skin?
It serves as a barrier for blocking microbes from deeper tissues.
It serves as a host to approximately 1 trillion microbes.
It is the largest human organ and covers 16 square feet of surface.
The skin can be divided into two main sections: a deeper one and a superficial one. What is the superficial layer of the skin called?
Which of the following statements are true of human papillomavirus?
Treatment can involve freezing, burning, and surgical removal.
There are different subtypes. The subtype that causes warts on the soles of the feet is different than the one that causes warts on the palms of the hands.
The infection depicted in the photo is typically caused by a child sucking his or her thumb when the child has a cold sore. What is the name of this infection?
Which of the following diseases has been eradicated?
Which of the following statements are true of smallpox?
Humans are the only known reservoir for the virus that causes this disease.
There are no FDA-approved treatments for smallpox, and the virus is considered a bioterrorism threat.
What is the area of the skin served by a specific nerve called?
Which viruses or diseases commonly affect the skin?
Match the diseases with the correct descriptions.
A person who has this disease could potentially transmit chickenpox to the recipient.: shingles
One symptom of this disease is painful oral lesions. There is no vaccine for this disease in the United States.: hand, foot, and mouth disease
This disease can cause death from multi-organ failure. It has been eradicated.: smallpox
The main symptom of this disease is a pruritic vesicular rash. A potential complication of this disease is shingles.: chickenpox
When it was first discovered, the disease commonly known as German measles was thought to be measles because of its similar macropapular rash, but German measles is caused by a completely different virus than ordinary measles. In children, the disease is usually mild and has a short duration, but in adults, German measles can be more serious. It can cause joint pain and can pass through the placenta of a pregnant woman and cause defects in the developing fetus. What is the scientific name of this disease?
The slapped cheek rash pictured is pathognomonic for erythema infectiosum (fifth disease). What does pathognomonic mean?
a sign or symptom that is characteristic of a particular disease
Roseola is a disease that causes three to five days of high fevers in very young children. It is usually caused by strains of human herpes virus (HHV). The virus is present in many people but remains latent, meaning hidden and not manifesting the disease.
There are vaccines available for measles, rubella, chickenpox, and some strains of common warts.
Which of the following statements are true?
Treatment of viral skin diseases usually involves supportive therapy.
Diagnoses of skin diseases are usually based on clinical presentation.
Which of the following are true of herpes simplex viruses 1 and 2 (HSV-1 and HSV-2)?
They can cause corneal infections in the eye.
HSV-1 is present in active or latent form in 60%-90% of older adults and can lie dormant in the trigeminal nerve ganglion.
The majority of viruses that cause a rash first access the body through the respiratory tract.
This viral disease is one of the six exanthem diseases of childhood. Its portal of entry is the respiratory tract or the conjunctiva. It causes Koplik's spots and a maculopapular rash as immune cells kill the virally infected endothelial cells of blood vessels. What is the name of this disease?
As pictured, measles usually start with these white spots on the buccal mucosa. What are the spots called?
Which of the following statements regarding methicillin-resistant Staphylococcus aureus (MRSA) are correct?
Vancomycin can be used to treat MRSA.
MRSA first appeared as a nosocomial infection.
Methicillin is no longer used in the United States.
Which of the following are known to cause eye disease?
Which of the following is not a virulence factor of certain strains of S. pyogenes?
This photo depicts an outbreak of shingles that ran along a certain branch of the trigeminal nerve, affecting the eye, eyelids, forehead, and nose. The resulting eye disease is known as which of the following?
herpes zoster opthalmicus
Which of the following organisms are known to cause burn wound infections?
Gram-negative bacteria from the intestinal tract
Aspergillus and Candida
Match the following diseases with the correct descriptions.
This disease is caused by Clostridium perfringens. Symptoms include necrotic tissue and a foul-smelling odor: gas gangrene
Symptoms include a shiny, fiery red, raised rash with an uneven surface, like orange peel: erysipelas
Usually caused by staph and strep, symptoms of this disease include small papular lesions that often ooze and crust.: impetigo
One side effect of this disease is turned-in eyelids. Corneal opacifications and blindness are possible complications.: trachoma
Which of the following statements regarding diabetes wounds is not correct?
diabetic hand wounds are the number one cause of limb amputations in the United States
Which of these are ways to diagnose fungal skin diseases?
microscopic examination of potassium hydroxide (KOH) preparations of skin flakes or hair
culturing on Sabouraud agar
Herpes viruses are a major cause of keratitis in the United States.
Match each condition to its primary symptom.
inflammation of the conjunctiva: conjuctivitis
infections of the inner structures of the eye: endopthalmitis
inflammation of the cornea: keratitis
The natural reservoir for S. pyogenes is the human intestinal tract.
Which of the following organisms is a Gram-negative opportunistic pathogen that has many virulence factors, including exotoxins A and S, that kill host cells? This organism is found ubiquitously in the environment and is a common cause of wound infections.
Which statement about necrotizing fasciitis is not true?
antibody therapy alone is the most effective treatment
Immediately after a severe burn, the surface of the wound is essentially heat sterilized.
What term, which is Greek for "skin plants," indicates fungi that love human skin?
Which of the following organisms are the two major contributors to bacterial skin infections?
This photo depicts a fungal infection of the scalp. What is the specific name for such an infection?
Methicillin is an antibiotic normally used against staphylococcal infections; however, MRSA strains are resistant to it. Which of the following alternative drugs might be used?
Which of the following viral infections of the skin starts with a condition known as "Koplik's spots"?
Different strains of Streptococcus pyogenes have different virulence factors, giving these microbes much versatility. Virulence factors include which of the following?
A capsule that, when thick, will help the organism avoid phagocytosis by macrophages
A cell wall containing lipoteichoic acid, thought to facilitate adherence to pharyngeal epithelial cells
Enzymes that lyse blood cells (streptolysins)
Diagnosis of fungal skin diseases is made from their clinical appearance and by microscopic examination of ___ preparations of skin flakes or hair.
Medieval doctors, ignorant of microscopic fungi but well versed in Latin, called fungal infections "tinea" (Latin for "gnawing worm"). Thus, if the lesion sits on the scalp, it is called which of the following?
Pseudomonas aeruginosa (a Gram-negative, aerobic rod) is a major cause of serious wound infections owing to its wealth of virulence factors and its high level of antibiotic resistance. Which of the following is incorrect regarding P. aeruginosa in wound infections?
It is a primary pathogen, infecting healthy individuals.
Which of the following are characteristics of all mucous membranes?
Composed of epithelial cells
Serve as a barrier to protect the structures they cover
Line the inside of the body
Which of the following viral skin infections can be prevented by a vaccination?
German measles (rubella)
Varicella zoster infection of the epidermal cells produces fluid accumulation that results in the characteristic vesicles of chickenpox. The virus is transferred by which of the following methods?
Inhalation when aerosolized
There are two possible infection pathways in a VSV infection. In the (A) _____ infection, the virus expresses genes that allow it to produce more viruses. This ultimately kills the cell. In the (B) _____infection pathway, the virus expresses genes that allow the DNA circle to persist within the cell for decades.
Conjunctivitis caused by staphylococci and streptococci includes which of the following symptoms?
Mucopurulent discharge that can produce crusting of the affected eye
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