Mastering Micro Ch 15

Disease research and epidemiology bring together many different facets to help us better understand disease pathology and spread. Which of the following statements are true? - Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host. - The interactions that occur between a microbe and host influence the evolution of both. - The terms pathogenicity and virulence can be used interchangeably to describe the severity of an infection. - Some pathogens are able to cause disease within a host without penetrating the body. - The ID50 value refers to the number of microbes needed to cause half of an infected population to die. - Intoxications result from a bacterial infection in which a large amount of bacterial toxin is produced.

- Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host. - The interactions that occur between a microbe and host influence the evolution of both. - Some pathogens are able to cause disease within a host without penetrating the body.

Considering the pathology of a cytokine storm, select possible strategies that would be likely to diminish the harmful effects of superantigen toxins. - Blocking the synthesis of lipopolysaccharide in gram-negative bacteria - Blocking the separation of the A and B components of the exotoxin - Blocking molecular determinants on superantigens that interacts with T cells - Neutralizing circulating cytokines - Blocking host cell receptor-mediated endocytosis - Blocking secretion of proteins by bacterial cells - Blocking the release of cytokines from T cells

- Blocking molecular determinants on superantigens that interacts with T cells - Neutralizing circulating cytokines - Blocking secretion of proteins by bacterial cells - Blocking the release of cytokines from T cells

Which of the following strategies might be used to block the activity of an A-B toxin? - Interfering with lipopolysaccharide synthesis in gram-negative bacteria - Blocking separation of the A and B components of the toxin - Blocking receptor-mediated endocytosis in cells targeted by the A-B toxin - Blocking host cell receptors to which A-B toxins bind - Inhibiting the secretion of proteins from a bacterial cell - Blocking the binding sites on the B portion of an A-B toxin - Inhibiting cytokine release stimulated by endotoxin

- Blocking separation of the A and B components of the toxin - Blocking receptor-mediated endocytosis in cells targeted by the A-B toxin - Blocking host cell receptors to which A-B toxins bind - Inhibiting the secretion of proteins from a bacterial cell - Blocking the binding sites on the B portion of an A-B toxin

Which of the following are properties of exotoxins? - Exotoxins target specific cellular structures or molecules. - Exotoxins are released from the cell during death or replication. - Very small amounts of exotoxin can be lethal. - Exotoxins are extremely heat stable. - Exotoxins are protein molecules. - Exotoxins are produced primarily by gram-negative bacteria.

- Exotoxins target specific cellular structures or molecules. - Very small amounts of exotoxin can be lethal. - Exotoxins are protein molecules.

Consider the structure of a plasma membrane. Select the mechanisms through which a toxin is likely to disrupt the plasma membrane of a host cell. - Blocking synthesis of transport proteins - Binding of the toxin to the peptidoglycan layer - Binding of the toxin to the lipopolysaccharide layer - Insertion of a protein channel in the host cell plasma membrane - Disruption of phospholipid bilayer

- Insertion of a protein channel in the host cell plasma membrane - Disruption of phospholipid bilayer

Select the statements that correctly describe endotoxins. - Symptoms caused by endotoxin may actually worsen after treatment of an infection caused by gram-negative bacteria. - Sterilized items may contain endotoxin and cause a reaction in a patient. - Endotoxins may cause a life-threatening drop in blood pressure known as endotoxic shock. - Endotoxin causes a strong immune response and abundant antibody production in the host. - Drugs that neutralize endotoxin will kill gram-negative bacteria. - Endotoxin can be used to vaccinate individuals. - Endotoxin can cause fever, chills, weakness, and fatigue.

- Symptoms caused by endotoxin may actually worsen after treatment of an infection caused by gram-negative bacteria. - Sterilized items may contain endotoxin and cause a reaction in a patient. - Endotoxins may cause a life-threatening drop in blood pressure known as endotoxic shock. - Endotoxin can cause fever, chills, weakness, and fatigue.

The ability of Vibrio cholerae to cause disease depends on a number of factors. Which of the following are requirements for causing disease within a host? - gaining access to the host via a portal of entry - depleting the host of nutrients at the site of infection - adherence to host tissues - direct damage of host tissues - evasion of host defenses - production of exotoxins

- gaining access to the host via a portal of entry - adherence to host tissues - evasion of host defenses

Which of the following would be an example of an infection initiated via the parenteral route? a. An individual contracts gonorrhea as a result of unprotected sex. b. An individual contracts a hookworm infection as a result of walking around outside barefoot. c. An individual contracts hepatitis B from an accidental stick with a contaminated needle. d. An individual contracts a gastrointestinal infection by consuming contaminated water.

. An individual contracts hepatitis B from an accidental stick with a contaminated needle.

Although cholera can be treated with antibiotics, data suggest that antibiotic treatment alone is NOT the most effective therapy. Which of the following statements describes the most likely reason for supplementing antibiotic therapy? a. As with V. cholerae, the acidic environment of the stomach can have a negative impact on antibiotic activity. b. The production of cholera toxin helps V. cholerae resist antibiotic treatment. c. Because V. cholerae is a gram-negative organism, it is not very effectively treated with antibiotics. d. Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.

. Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.

Which of the following is NOT a membrane-disrupting toxin? a. streptolysin S b. streptolysin O c. hemolysin d. A-B toxin e. leukocidin

A-B toxin

All of the following are used by bacteria to attach to host cells EXCEPT a. capsules. b. ligands. c. A-B toxins. d. M protein. e. fimbriae.

A-B toxins.

Which domain of the A-B toxin binds to cell surface receptors on the host cell? a. Both the A and B domains have the ability to bind to cell surface receptors. b. A-B toxins do not bind to cell surfaces. c. B domain d. A domain

B domain

All of the following bacteria release endotoxin EXCEPT a. Haemophilus influenzae. b. Neisseria meningitidis. c. Proteus vulgaris. d. Clostridium botulinum. e. Salmonella typhi.

Clostridium botulinum.

Which of the following would be the first sign of an infection that resulted in the release of endotoxin? a. Fever b. Weakness c. Pain d. Nausea

Fever

Why is a release of endotoxin into the bloodstream potentially deadly? a. It causes necrosis of the liver. b. Endotoxin can quickly enter the brain from the bloodstream, causing brain damage. c. It can lower blood pressure and cause the patient to go into shock. d. It results in dehydration of the patient.

It can lower blood pressure and cause the patient to go into shock.

Bacterium ID50 E. coli O157:H7 20 Legionella pneumophila 1 Shigella 10 Treponema pallidum 57 Which organism in the table causes the most severe disease? a. Treponema pallidum b. E. coli O157:H7 c. Legionella pneumophila d. Shigella e. It cannot be determined from the information provided.

It cannot be determined from the information provided.

Bacterium ID50 E. coli O157:H7 20 Legionella pneumophila 1 Shigella 10 Treponema pallidum 57 Which organism in the table most easily causes an infection? a. Shigella b. Legionella pneumophila c. Treponema pallidum d. E. coli O157:H7 e. The answer cannot be determined based on the information provided.

Legionella pneumophila

Endotoxins are also known as a. prostaglandins. b. cytokines. c. interleukin-1. d. Lipid A.

Lipid A.

Which of the following statements about adherence is true? a. Most bacterial adhesins are glycoproteins or lipoproteins. b. Most bacteria can adhere to any cell in the host. c. Adhesins are always located on the bacterium's cell membrane. d. The host cell receptors for bacterial adhesins are usually proteins.

Most bacterial adhesins are glycoproteins or lipoproteins.

Which statement regarding endotoxins is true? a. The effects of endotoxins vary greatly, depending on the specific bacterium the produces them. b. Endotoxins induce host cells to produce effective antitoxins that help to protect them against the toxin's effects. c. One consequence of endotoxins is the activation of blood-clotting proteins. d. Endotoxins are part of the outer portion of the cell wall of gram-positive bacteria.

One consequence of endotoxins is the activation of blood-clotting proteins.

All of the following organisms produce exotoxins EXCEPT a. Clostridium botulinum. b. Corynebacterium diphtheriae. c. Salmonella typhi. d. Staphylococcus aureus. e. Clostridium tetani.

Salmonella typhi.

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? a. Staphylococcal enterotoxin is the more lethal of the two toxins. b. Shiga toxin is more lethal than staphylococcal enterotoxin. c. The parenteral route is the preferred portal entry for Shigella bacteria. d. More organisms of Staphylococcal bacteria must be ingested to cause infection, as compared Shigella bacteria.

Shiga toxin is more lethal than staphylococcal enterotoxin.

How are superantigens different from other types of exotoxins? a. Superantigens cause an overstimulation of the host immune system. b. Superantigens must be endocytosed into a target cell before becoming active. c. Superantigens are comprised of two functional domains. d. Superantigens only act against host neurons.

Superantigens cause an overstimulation of the host immune system.

What do hyaluronidase and kinase have in common? a. They are both critical components of microbial capsules. b. They both directly prevent phagocytosis. c. They are both enzymes involved in evading host defense. d. They both break down components of the extracellular matrix. e. All of the above are correct.

They are both enzymes involved in evading host defense.

Which of the following statements about exotoxins is generally FALSE? a. They are composed of proteins. b. They are resistant to heat. c. They are produced by gram-positive bacteria. d. They have specific methods of action. e. They are more potent than endotoxins.

They are resistant to heat.

Some studies have indicated that the ID50 for Vibrio cholerae can be as high as 108 organisms. Which of the following most likely explains the requirement for this relatively high ID50? a. To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach. b. Because V. cholerae cells are relatively small compared to host cells, thousands of bacteria must infect each cell to cause disease. c. Because the major virulence factor of V. cholerae is cholera toxin, large numbers of bacteria are required to produce enough toxin to cause disease. d. V. cholerae does not produce enough virulence factors to overcome the host response and cause disease.

To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.

When would endotoxins be released from a bacterial cell? a. When the cell attaches to a host cell in the human body b. When the cell dies c. When the cell moves toward a energy source d. During bacterial conjugation

When the cell dies

Which of the following virulence factors could directly prevent phagocytosis and/or phagocytic degradation? a. capsules b. M proteins c. waxy lipids d. all of the above e. none of the above

all of the above

Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage? a. influenza b. cholera c. ringworm d. yellow fever

cholera

Superantigens produce intense immune responses by stimulating lymphocytes to produce a. cytokines. b. leukocidins. c. exotoxins. d. endotoxins. e. interferons.

cytokines.

An exotoxin that has the ability to kill or damage host cells is referred to as a(n) a. cytotoxin. b. neurotoxin. c. superantigen. d. A-B toxin. e. enterotoxin.

cytotoxin.

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 a. viral infection. b. endotoxin. c. exotoxin. d. bacterial infection. e. The answer cannot be determined based on the information provided.

endotoxin.

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 a. staphylococcal enterotoxin. b. erythrogenic toxin. c. aflatoxin. d. botulinum toxin. e. cholera toxin.

erythrogenic toxin.

Antibiotics can lead to septic shock if used to treat a. helminth infestations. b. protozoan infections. c. gram-positive bacterial infections. d. viral infections. e. gram-negative bacterial infections.

gram-negative bacterial infections.

All of the following are examples of entry via the parenteral route EXCEPT a. surgery. b. injection. c. bite. d. hair follicle. e. skin cut.

hair follicle.

Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use? a. skin only b. parenteral only c. mucous membranes only d. skin and parenteral e. skin, parenteral, and mucous membranes

mucous membranes only

A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a(n) a. membrane disrupting toxin. b. superantigen. c. enterotoxin. d. neurotoxin.

neurotoxin.

Which of the following contributes to the virulence of a pathogen? a. numbers of microorganisms that gain access to a host b. evasion of host defenses c. toxin production d. numbers of microorganisms that gain access to a host and evasion of host defenses e. numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

Endotoxins are a. associated with gram-positive bacteria. b. molecules that bind nerve cells. c. part of the gram-negative cell wall. d. A-B toxins. e. excreted from the cell.

part of the gram-negative cell wall.

Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed, a. Vibrio would bind to target cells. b. Vibrio would not produce cholera toxin. c. polypeptide B would not be able to enter the cells. d. polypeptide A would bind to target cells. e. polypeptide A would enter the cells.

polypeptide B would not be able to enter the cells.

Endotoxins in sterile injectable drugs could cause a. infection. b. nerve damage. c. giant cell formation. d. no damage, because they are sterile. e. septic shock symptoms.

septic shock symptoms.

A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a(n) a. membrane disrupting toxin. b. superantigen. c. enterotoxin. d. cytotoxin.

superantigen

Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to a. lipid A. b. erythrogenic toxin. c. membrane-disrupting toxins. d. A-B toxins. e. superantigens.

superantigens.

The ID50 is a. the dose that will cause an infection in 50 percent of the test population. b. a measure of pathogenicity. c. the dose that will cause an infection in some of the test population. d. the dose that will kill 50 percent of the test population. e. the dose that will kill some of the test population.

the dose that will cause an infection in 50 percent of the test population.

In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used? a. to confirm the diagnosis of gas gangrene b. to check for enterotoxins c. to ensure that a sterilized medical device is free of endotoxin d. to detect the presence of the botulinum toxin

to ensure that a sterilized medical device is free of endotoxin

All of the following contribute to a pathogens invasiveness EXCEPT a. toxins. b. hyaluronidase. c. coagulases. d. capsules. e. cell wall components.

toxins.

Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by a. conjugation. b. transformation. c. infecting a pathogenic Vibrio cholerae. d. transduction. e. phagocytosis.

transduction.