Chapter 25

Why is it necessary to test for endotoxin in water used for injectable drug preparations?

Because if you have endotoxin in water and give it to a patient it can cause a systemic drop in their blood pressure which can cause death.

Why do certain pathogens only infect specific hosts?

Because some pathogens can only bind to certain receptors; there are many different receptors coating both the pathogen and tissues where the bacteria/virus binds

How do streptokinase and coagulase promote bacterial infection and invasion?

Both manipulate clotting. Coagulase forms clots while streptokinase breaks them down.

Why do botulism and tetanus show such opposing symptoms?

Botulism: Normal transmission of a nerve impulse to a muscle cell requires acetylcholine interaction with a muscle receptor; botulinum toxin poisons the neuron and prevents signals to the muscle preventing muscle contraction Tetanus: blocks glycine release so the motor neurons can't be inhibited, resulting in continual release of acetylcholine and muscle contraction

What is an IgAase and why would a bacterial pathogen produce one?

Cleave IgA which prevents the pathogen adherence

Give an example of a cytolytic exotoxin and a superantigen exotoxin, as well as the bacteria that produce each.

Cytolytic: hemolysins produced by streptococci. Superantigen: toxic shock toxin -1 produced by Streptococcus pyogenes and Staphylococcus aureus

What is a nosocomial infection?

Healthcare associated infections (infections caused by health care provider passing it from patient to patient)

Identify host factors that limit or accelerate infection of a microorganism at selected local sites.

Hyaluronidase, coagulase, streptokinase.

What circumstances can contribute to attenuation of a pathogen?

If the pathogen is kept in a lab culture rather than isolated from diseased animals, the virulence decreases

Distinguish between infection and disease.

Infection is when a microorganism is established and growing in a host whether or not it is hurt, a disease is when there is actual damage/injury to the host that impairs function.

What event is required but not sufficient to cause an infectious disease?

Microbial Adherence

Describe the molecules or structures that facilitate pathogen adherence to host tissues?

Molecules: Adhesins are glycoproteins or lipoproteins found on the pathogen's surface that enable it to bind to host cells. Structures: Capsules are sticky and contain specific receptors to facilitate attachment on host tissues Fimbriae: functions in attachment pili: typically longer and fewer in number than fimbriae, some function in conjugation Flagella: also facilitate adherence to host cells but are primarily for movement

Name some pathogens that produce exotoxins and what is their mode of action.

Pseudomonas aeruginosa- bum and certain wound and ear infections cystic fibrosis lung infections. Inhibits eukaryotic protein synthesis Cholera: Induces fluid loss from intestines Whooping cough: Blocks G protein function; kills cells- Anthrax: Combine to cause cell death

Which is the more serious condition, bacteremia or septicemia, and why?

Septicemia; in bacteremia, bacteria are only present in the bloodstream, in septicemia, the bacteria are multiplying and spread all over the body to infect any part, which can lead to massive inflammation, septic shock, and death

What major virulence factors are produced by Salmonella?

Siderophores Type I fimbriae Virulence plasmid Cytotoxin Vi capsule agent Flagellum Pathogenicity O antigen Antiphagocytic proteins Endotoxin Injectisome Enterotoxin

How can activity of a hemolytic exotoxin be detected?

Since they lyse cells, those lysed cells look yellow and are see-through

Which genus produces hyaluronidase?

Streptococcus

What part of Escherichia coli cell contains endotoxin? Why do gram-positive bacteria not produce endotoxins?

The lipid A of the LPS They don't have an LPS layer

At what body sites do pathogens typically attach and colonize?

They typically gain access through a portal of entry such as under mucous membranes or the skin through penetration of these sites from puncture wounds, insect bites, cuts, or other abrasions

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

a)B domain

Which of the following is more likely to cause urinary tract infections? a)Fimbriated strains of Escherichia coli b)Nonfimbriated strains of Escherichia coli c)Both fimbriated and nonfimbriated strains of Escherichia coli d)None of the answers are correct.

a)Fimbriated strains of Escherichia coli

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as a)LD50 (lethal dose50). b)Antigen dose50. c)Virulence-50. d)Death rate-50.

a)LD50 (lethal dose50).

Meningitis and gonorrhea are caused by? a)Neisseria species b)measles virus c)Pseudomonas species.

a)Neisseria species

Which genus produces hyaluronidase? a)Streptococcus b)Mycobacterium c)Shigella d)Procholorococcus

a)Streptococcus

Diphtheria toxin is a)an AB toxin. b)a superantigen toxin. c)a cytolytic toxin. d)a type of endotoxin.

a)an AB toxin.

Which of the following does NOT affect pathogen growth? a)availability of microbial nutrients b)pH c)temperature d)All of these answer choices affect growth.

a)availability of microbial nutrients b)pH c)temperature d)All of these answer choices affect growth.

Tetanus toxin causes a)muscles to be unable to relax. b)muscles to be unable to contract. c)hemolytic uremic syndrome. d)severe diarrhea.

a)muscles to be unable to relax.

The best term to describe the general process by which microorganisms cause diseases is known as a)pathogenesis. b)virulence. c)invasion. d)infection.

a)pathogenesis.

The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called a)septicemia. b)cancer. c)pathogenesis. d)bacteremia.

a)septicemia.

What is an opportunistic pathogen? What steps can a person take to help avoid opportunistic infections?

are those caused by organisms that do not cause disease in healthy hosts Practice safe food preparation, take care around animals and people, get vaccinated

__________ is a damage or injury to a host organism that impairs its function. a)Transmission b)Disease c)Trauma d)Infection

b)Disease

________ are toxic proteins released from the pathogen during normal growth. a)Macrotoxins b)Exotoxins c)Microtoxins d)Endotoxins

b)Exotoxins

Which of the following features of Salmonella prevent it from being phagocytosed? a)Fimbriae b)Flagella c)Invasins

b)Flagella

________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts. a)Immunocompromised infections b)Healthcare-associated infections c)Virulent infections d)Pathogenic infections

b)Healthcare-associated infections

Where do Salmonella pathogens grow and replicate in the infected host? a)Inside intestinal epithelial cells b)Inside phagocytes c)Inside Shigella cells d)Inside M cells

b)Inside phagocytes

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

b)Lipid A

Which of the following is NOT a subunit of lipopolysaccharide (LPS)? a)core polysaccharide b)M protein c)O-specific polysaccharide d)lipid A

b)M protein

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

b)Molecules that are capable of destroying phagocytes

Compared with an endotoxin, would a bacterial exotoxin generally be more likely to function after it had been significantly heated? a)Yes, because exotoxins are proteins and nonliving but endotoxins are part of the bacterial cell wall. b)No, because exotoxins are heat-labile and less resistant to heating than endotoxins. c)Yes, because exotoxins are very heat stable compared to endotoxins. d)No, because exotoxins are carbohydrates and endotoxins are proteins.

b)No, because exotoxins are heat-labile and less resistant to heating than endotoxins.

What is the etiologic agent of typhoid? a)E. coli b)Salmonella c)Shigella

b)Salmonella

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

b)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? a)They are secreted directly into the epithelial cells from the M cells. b)They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another. c)They are secreted by phagocytes. d)They lyse the M cell, releasing thousands of new cells to infect other host cells.

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

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)During bacterial conjugation d)When the cell moves toward a energy source

b)When the cell dies

Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells. a)amylase b)coagulase c)collagenase d)lipase

b)coagulase

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

b)cytotoxin

Which of the following is an important factor in the development of dental caries? a)low salt diet b)high sugar diet c)high acid diet d)high salt diet

b)high sugar diet

Decalcification of the tooth enamel is caused by a)lipopolysaccharide. b)lactic acid. c)dextrans. d)formic acid.

b)lactic acid.

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

b)neurotoxin

Pathogenicity is the ability a)of the host to inflict damage on the pathogen. b)of the pathogen to inflict damage on the host. c)of the host to resist damage by the pathogen. d)None of these are correct.

b)of the pathogen to inflict damage on the host.

Influenza virus targets a)throat epithelium. b)respiratory epithelium. c)gastrointestinal cells. d)oral cavity cells.

b)respiratory epithelium.

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)cytotoxin b)superantigen c)enterotoxin d)membrane disrupting toxin.

b)superantigen

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

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

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

c)Fever

Which of the following enzymes breaks down the "glue" that holds cells together? a)Fibrinolysin b)Streptokinase c)Hyaluronidase d)Collagenase

c)Hyaluronidase

________ in saliva cleaves glycosidic linkages in the peptidoglycan that is present in bacterial cell walls, weakening the wall and potentially causing cell lysis. a)Lipid A b)Mucus c)Lysozyme d)Fibrin

c)Lysozyme

Where is the site of Shigella attachment in the host? a)Intestinal epithelial cells b)Leukocytes c)M cells d)Phagocytes

c)M cells

Shiga toxin is an enterotoxin that is produced by a)Escherichia coli O157:H7. b)Vibrio cholerae. c)Shigella dysenteriae. d)Clostridium tetani.

c)Shigella dysenteriae.

Exotoxins are ________, but endotoxins are ________. a)carbohydrates / proteins b)lipids / proteins c)proteins / lipopolysaccharide-lipoprotein complexes d)lipopolysaccharide-lipoprotein complexes / proteins

c)proteins / lipopolysaccharide-lipoprotein complexes

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

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

Which of the following virulence factors would be found in Staphylococcus aureus? a)Hyaluronidase b)Streptokinase c)Collagenase d)Staphylokinase

d)Staphylokinase

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

d)Superantigens cause an overstimulation of the host immune system.

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

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

Septicemia is an example of a)an autoimmune infection b)a transient infection. c)a localized infection. d)a systemic infection.

d)a systemic infection.

Cytolytic toxins a)damage host cytoplasmic membrane. b)cause cell lysis and death. c)are extracellular proteins. d)are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

d)are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

The decrease or loss of virulence of a pathogen is referred to as a)lethal dose. b)disinfectivity. c)aging. d)attenuation.

d)attenuation.

The condition that results when some bacteria are shed in the bloodstream and distributed to distant parts of the body but do not reproduce in the blood is called a)septicemia. b)uremia. c)erythemia. d)bacteremia.

d)bacteremia.

An outer coat consisting of a dense, well-defined polymer layer surrounding a cell and used in attachment is called a a)lipopolysaccharide layer. b)cytoplasmic membrane. c)pilus. d)capsule.

d)capsule

Which of the following is a category of exotoxin? a)β-toxin b)α-toxin c)lipophilic toxin d)cytolytic toxin

d)cytolytic toxin

Which of the following is a way to prevent attenuation and maintain virulence in a bacterium? a)laboratory subculture b)antibiotic therapy c)polymerase chain reaction (PCR) d)inoculating an animal with the bacterium

d)inoculating an animal with the bacterium

Siderophores are a)inorganic molecules that help in active transport. b)molecules that aid directly in attachment to host cells. c)toxins that affect the gastrointestinal tract. d)organic molecules that help pathogens take up iron.

d)organic molecules that help pathogens take up iron.

The process by which white blood cells ingest and kill bacteria is called a)translation. b)transcription. c)exocytosis. d)phagocytosis.

d)phagocytosis.

Capsules are particularly important for a)allowing bacteria to become more phagocytic. b)making bacteria more vulnerable to host defense mechanisms. c)making bacteria less pathogenic. d)protecting bacteria from host defense mechanisms.

d)protecting bacteria from host defense mechanisms.

Staphylococcus aureus and Streptococcus pyogenes strains can produce ________ that cause(s) the severe and sometimes life-threatening symptoms of toxic shock syndrome. a)endotoxin b)cytolytic c)AB toxins d)superantigen toxins

d)superantigen toxins

Measles viruses are capable of inactivating host defenses by? a)producing leukocidins b)producing superantigens c)destroying complement proteins d)suppressing the immune system

d)suppressing the immune system

Certain traits that allow pathogens to create infection and cause disease are termed? a)streptokinases bhyaluronidases c)collagenases d)virulence factors

d)virulence factors

Explain how diphtheria toxin, botulism toxin, tetanus toxin, and cholera toxin work.

diphtheria toxin- inhibits eukaryotic protein synthesis botulism toxin- causes flaccid paralysis tetanus toxin- causes spastic paralysis; prolongs contraction cholera toxin- induces fluid loss from intestine

T/F: Cholera begins following a bite from a mosquito.

false

T/F: Clostridium botulinum cannot produce toxins in improperly preserved foods.

false

T/F: Gram-positive bacteria produce endotoxins.

false

T/F: Hyaluronidase worsens infection by causing damage to red blood cells.

false

T/F: The toxic lipopolysaccharides produced by most gram-negative bacteria are called exotoxins

false

What are virulence factors? How can the LD50 test be used to define virulence of a pathogen?

toxic or destructive substances produced by the pathogen that directly or indirectly enhance invasiveness and host damage by facilitating and promoting infection; examples: exotoxins, capsules By testing the amount of an agent it takes to kill 50% of the test subjects; highly virulent pathogens show little difference in the number of cells required to kill 100% vs. 50% of the population.

T/F: Clostridium botulinum are endospore-forming bacteria normally found in the soil.

true

T/F: Endotoxins are released in large amounts only when cells lyse.

true

T/F: Streptococcus mutans produces dextran to aid in attachment to tooth surfaces.

true

T/F: The Limulus amebocyte lysate assay is used to detect endotoxin in clinical samples such as serum or cerebrospinal fluid.

true