Chapter 10: Host-microbe Interactions and Pathogenesis

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

B domain

Which biosafety level is incorrectly matched with its description? BSL-3: serious, lethal pathogens though some diseases may be treatable BSL- 2: known pathogens but the disease is treatable or preventable BSL-1: non-pathogens or those that rarely cause disease in healthy people BSL-4: dangerous, lethal pathogens with no cures or treatments BSL-2+: known animal pathogens which do not infect humans

BSL-2+: known animal pathogens which do not infect humans

How are symptoms of an infection associated with the mode of transmission of the pathogen? Bodily fluids produced during an illness are often rich in infectious organisms. The worse the patient feels, the more likely the disease is transmissible to others. Lack of symptoms indicates that the infection is not transmissible to others. There is no relationship between symptoms and mode of transmission. Bodily fluids are rarely a source of disease transmission during an infection.

Bodily fluids produced during an illness are often rich in infectious organisms.

How can capsules enable bacteria to evade the immune system? A capsule is a superantigen that distracts the immune system. Capsules can bind up IgA, rendering it inactive. Capsules block the complement biding sites on the surface of the pathogen.

Capsules block the complement biding sites on the surface of the pathogen.

Which microorganism requires the low pH inside a phagolysosome in order to reproduce? Coxiella burnetii Streptococcus pyogenes Haemophilus influenzae Streptococcus pneumoniae

Coxiella burnetii

Which of the following features of Salmonella prevent it from being phagocytosed? Fimbriae Flagella Invasins

Flagella

Which of the following is/are examples of virulence factors? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Flagella Capsule Complement Iron-binding proteins

Flagella Capsule Iron-binding proteins

Which of the following is an example of dysbiosis? Following extended use of amoxicillin, your patient develops oral thrush as a result of the overgrowth of Candida albicans. Your patient regularly ingests probiotics such as Lactobacillus acidophilus to improve symptoms associated with irritable bowel syndrome. Staphylococcus epidermidis, a normal flora found on the skin, secretes bacteriocidins to kill rival pathogenic bacteria. Patient serum antibodies are used to neutralize the influenza virus.

Following extended use of amoxicillin, your patient develops oral thrush as a result of the overgrowth of Candida albicans.

Septic shock is typically associated with Gram-negative infections. superantigens. either Gram-negative or Gram-positive infections. exotoxins or endotoxin. exotoxins.

Gram-negative infections.

Which of the following can be a potential disease reservoir for a pathogen which infects humans? only humans or inanimate objects that an infected human directly handles environmental niches such as soil or water only humans Humans, non-human animals, inanimate objects, or environmental niches can all serve as reservoirs for a pathogen which infects humans. only humans or non-human animals

Humans, non-human animals, inanimate objects, or environmental niches can all serve as reservoirs for a pathogen which infects humans.

Which of the following enzymes breaks down the "glue" that holds cells together? Hyaluronidase Streptokinase Collagenase Fibrinolysin

Hyaluronidase

How does the protozoan Trypanosoma evade detection by the immune system? It produces a capsule which is composed of polysaccharides similar to those found in the host. It can resist oxidation inside macrophages. It can change the surface antigens frequently, preventing the immune system from tracking it. It prevents phagosome-lysosome fusion.

It can change the surface antigens frequently, preventing the immune system from tracking it.

Where is the site of Shigella attachment in the host? Phagocytes Intestinal epithelial cells M cells Leukocytes

M cells

Which of the following criteria is/are used to assign pathogens to a specific biosafety level? To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Mode of transmission Level of infectivity Size of microorganism Availability of preventions and treatments for the disease

Mode of transmission Level of infectivity Availability of preventions and treatments for the disease

What are leukocidins? Molecules that are capable of destroying phagocytes Molecules that destroy the complement proteins Molecules that can degrade IgA

Molecules that are capable of destroying phagocytes

Meningitis and gonorrhea are caused by measles virus. Pseudomonas species. Neisseria species.

Neisseria species.

You receive an accidental needle stick from a needle contaminated with Hepatitis B virus. In this example, Hepatitis B enters the host through which portal of entry? Skin Transplacental Otic Parenteral entry

Parenteral entry

What is the etiologic agent of typhoid? Salmonella Shigella E. coli

Salmonella

Siderophores such as enterobactin promote virulence through which mechanism? Facilitates the invasion of the pathogen into host tissue Sequesters iron from the host Protects the pathogen from phagocytosis Functions as an outer membrane bacterial adhesin.

Sequesters iron from the host

Which of the following virulence factors would be found in Staphylococcus aureus? Staphylokinase Streptokinase Collagenase Hyaluronidase

Staphylokinase

Which of the following microorganisms use M protein to avoid destruction of a phagocyte? Streptococcus pneumoniae Haemophilus influenzae Streptococcus pyogenes Coxiella burnetii

Streptococcus pyogenes

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

Superantigens cause an overstimulation of the host immune system.

Which of the following is/are standard precaution(s)? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Surfaces must be disinfected. Airtight, pressurized, full-body hazardous material suits must be worn with immunocompromised patients. Hand hygiene should be performed before and after each patient contact New gloves should be worn when encountering blood, mucous membranes, non-intact skin, or other bodily fluids, and gloves should be changed between procedures.

Surfaces must be disinfected. Hand hygiene should be performed before and after each patient contact New gloves should be worn when encountering blood, mucous membranes, non-intact skin, or other bodily fluids, and gloves should be changed between procedures.

How does a capsule help certain bacteria evade detection by the immune system? The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign. Capsules have the ability to destroy antibodies secreted by the immune system. The capsule makes the bacterium too sticky to be phagocytosed by the immune cells. Capsules allow the bacteria to stick together, creating a larger mass that is too big for immune cells to engulf.

The capsule is composed of polysaccharides that are similar to those found in the host; thus, the immune system does not recognize it as foreign.

Which of the following provides the best definition of the term reservoir? An anatomical site that the pathogen uses for entry into the host. The habitat where a pathogen is typically found. The anatomical site that the pathogen uses to exit the host. The object which disseminates the pathogen from the environment to the host.

The habitat where a pathogen is typically found.

How is Streptococcus pneumoniae able to avoid destruction by a phagocyte? Their capsules make them "slippery" to phagocytes. They cause the lysosomes to empty their contents into the phagocyte, killing it. They prevent the fusion of the lysosome and phagosome.

Their capsules make them "slippery" to phagocytes.

Listeria monocytogenes is an intracellular bacterial pathogen that replicates within macrophages. Secretion of listeriolysin O and phospholipase helps the pathogen to escape phagolysosome formation following internalization by the host cell. In this example, listeriolysin O and phospholipase A perform which essential function? These virulence factors function as adhesins. These virulence factors help the pathogen find a portal of entry. These virulence factors help the pathogen sequester iron and other nutrients from the host cell. These virulence factors help the pathogen evade host defenses.

These virulence factors help the pathogen evade host defenses.

Which statement is true about standard precautions? They are in force only for bloodborne pathogens. They are used only when the patient is known to be infected with a BSL-2 or higher pathogen. They apply to all healthcare providers working with all patients. They are used in student labs that only handle BSL-1 pathogens They require full face shields, gloves, and barrier gowns for all patient contact situations.

They apply to all healthcare providers working with all patients.

How are immune cells able to detect foreign pathogens? They can compare the DNA sequences from the foreign cells to host DNA. They detect foreign, unfamiliar chemical substances released by the invading cells. They are able to detect structures on the surfaces of foreign cells that are not found in the host.

They are able to detect structures on the surfaces of foreign cells that are not found in the host.

How do fibrinolysins enhance a pathogen's virulence? They destroy the fibers that are found at the base of superficial tissues, allowing for deeper penetration by the pathogen. They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin. They destroy the molecules that hold cells together.

They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.

How do Shigella cells move between host cells? They are secreted by phagocytes. They are secreted directly into the epithelial cells from the M cells. They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another. They lyse the M cell, releasing thousands of new cells to infect other host cells.

They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another.

How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system? They cause fever, which destroys the complement proteins. They cause the immune system to destroy IgA antibodies. They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen. They cause the immune system to turn on itself.

They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.

A virulence study was performed using Staphylococcus aureus in mice. It was determined that the LD50 for the S. aureus alpha-toxin was 0.045 µg/kg of body weight toxin (a relatively low LD50). In the same mouse population, the ID50 was determined to be 200,000 cells (a relatively high ID50). What do these results taken together mean? This S. aureus strain is highly infectious, but its alpha-toxin is minimally-toxic. This S. aureus strain is less infectious, but its alpha-toxin is highly-toxic. This S. aureus strain is highly infectious, and its alpha-toxin is highly-toxic. This S. aureus strain is less infectious, and its alpha-toxin is minimally-toxic.

This S. aureus strain is less infectious, but its alpha-toxin is highly-toxic.

Which of the following microorganisms actually grows inside the macrophage? Leishmania Tuberculosis bacterium Legionella Shigella Streptococcus pneumoniae

Tuberculosis bacterium

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

cytotoxin

Which factors may result in a normal microbiota species causing disease? invasion of other tissues by the microbiota species dysbiosis due to antibiotic therapy or immune system attack on the host's own tissue dysbiosis due to antibiotic therapy immune system attack on the host's own tissues dysbiosis due to antibiotic therapy or invasion of other tissues by the microbiota species

dysbiosis due to antibiotic therapy or invasion of other tissues by the microbiota species

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

fever

Adhesins include molecules that bind to host factors such as fibronectin, sialic acid, and heparin / heparin sulfate. are limited to only a few known types. allow pathogens to stick to host tissues only in a nonspecific manner. include molecules that are typically found deep inside the pathogenic cell. make poor targets for vaccine development.

include molecules that bind to host factors such as fibronectin, sialic acid, and heparin / heparin sulfate.

Where do Salmonella pathogens grow and replicate in the infected host? Inside M cells Inside phagocytes Inside intestinal epithelial cells Inside Shigella cells

inside phagocytes

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

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

Endotoxins are also known as interleukin-1. cytokines. prostaglandins. Lipid A.

lipid A

Which method of hiding from the host immune system is incorrectly matched with its description? antigen variation: the pathogen frequently switches its antigens living intracellularly: a pathogen resides on the surface of a host cell where it is hidden by host cell surface molecules antigen mimicry: the pathogen's antigens are similar in structure to host molecules latency: a pathogen exists quietly inside the host cell antigen masking: the pathogen covers itself in host factors to avoid detection of its own antigens

living intracellularly: a pathogen resides on the surface of a host cell where it is hidden by host cell surface molecules

Escherichia coli living in the human large intestine is known to produce vitamin K and B-complex vitamins in exchange for a nutrient-rich habitat. This host-microbe interaction is an example of __________. commensalism mutualism dysbiosis parasitism

mutualism

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

neurotoxin

Which portal of entry is mismatched to its description? otic: pathogen enters via the ear urogenital: often associated with sexually-transmitted pathogens gastrointestinal: often involves fecal-to-oral transmission parenteral: pathogen is passed from mother to child through the placenta ocular: via the conjunctiva

parenteral: pathogen is passed from mother to child through the placenta

Exotoxins are secreted. the targets of some childhood vaccines. secreted and only made by Gram-positive bacteria. only made by Gram-positive bacteria. secreted and the targets of some childhood vaccines.

secreted and the targets of some childhood vaccines.

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) membrane disrupting toxin. cytotoxin. superantigen. enterotoxin.

superantigen

Measles viruses are capable of inactivating host defenses by producing superantigens. destroying complement proteins. suppressing the immune system. producing leukocidins.

suppressing the immune system.

ID50 describes the amount of toxin lethal to a 50-pound human or other animal. the percentage of individuals which will develop an infection after exposure to 50 cells or virions. the number of cells or virions which will kill 50 individuals. the number of cells or virions needed to establish an infection in 50 percent of exposed hosts. the number of cells or virions which will kill 50% of exposed hosts.

the number of cells or virions needed to establish an infection in 50 percent of exposed hosts.

Which type of bacterial toxin is matched incorrectly with its description? type 3 exotoxin: bind to a membrane receptor then enter the cell toxemia: a toxin produced during a viral infection type 1 exotoxin: bind to the targeted host cell at a membrane receptor but do not enter the cell endotoxin: enters the bloodstream during infection with Gram-negative bacteria type 2 exotoxin: disrupt and damage the host cell membrane leading to cell lysis

toxemia: a toxin produced during a viral infection

The degree or extent of disease that a pathogen causes is attenuation. pathogenicity. a host factor. toxicity. virulence

virulence

Certain traits that allow pathogens to create infection and cause disease are termed collagenases. streptokinases. hyaluronidases. virulence factors.

virulence factors.

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

when the cell dies

Toxemia is a condition where a vaccine is used to protect against a toxin. where a toxin has entered the bloodstream resulting in systemic effects. where a toxin acts as a superantigen. where a toxin is acting on tissues locally. that may describe both localized and systemic effects.

where a toxin has entered the bloodstream resulting in systemic effects.