MCB4403 Exam #4 With
Complete Solution
Pathogenicity - ANSWER the ability to cause disease
Pathogen - ANSWER An organism that causes disease
Virulence - ANSWER the degree of pathogenicity
Virulence factors - ANSWER traits of a microbe that promote pathogenicity
Pathology - ANSWER the study of disease
Etiology - ANSWER The study of the cause of disease
Pathogenesis - ANSWER the development of disease
Infection - ANSWER the growing and multiplying of pathogens in the host
Disease - ANSWER an abnormal state in which the body is not functioning normally.
T/F: Infection always leads to disease - ANSWER False. Most infections are removed by
the immune system.
________ have the ability to penetrate host defenses. - ANSWER Primary pathogens
_________ cause disease only in compromised hosts. - ANSWER Opportunistic
pathogens
What does "ID50" stand for? - ANSWER Infectious dose of 50% of the test population
What ID50 value would be the most virulent? - ANSWER The smaller value, because it
requires a lower to dose to infect the same amount of people.
What does "LD50" stand for? - ANSWER Lethal dose of a toxin for 50% of the test
population
What LD50 value would be most virulent? - ANSWER The smaller value, because it
requires a lower to dose to kill the same amount of people.
_______ are considered a _______ of infection because they may have inapparent
infections or latent disease. - ANSWER Carriers; reservoir
A pathogen of _________ origin is one that mutated from an animal. - ANSWER zoonotic
Give an example of a human reservoir of infection pathogen - ANSWER STDs
Give an example of an animal reservoir of infection pathogen - ANSWER rabies, lyme
,disease
Give an example of a nonliving reservoir of infection pathogen - ANSWER botulism,
tetanus, anthrax
What would be a common nonliving reservoir of infection? - ANSWER Soil
What are the three portals of entry? (that's what she said) - ANSWER skin, mucous
membrane, parenteral route
What is meant by the parenteral route of infection? - ANSWER entering the blood stream
through injection such as needles, mosquitos, and ticks
Vehicle transmission is through _______ - ANSWER an inanimate reservoir, for example,
food or water.
Vector disease transmission occurs from _______ - ANSWER an animal host to human
host
Mechanical vector disease transmission occurs when _____ - ANSWER an arthropods
carries pathogens on their feet, such as flies carrying typhoid fever.
Biological vector disease transmission occurs when _______ - ANSWER the pathogen
reproduces within the vector, for example, lyme disease in ticks.
_______ contact transmission requires close associate between the infected host and
susceptible host (ex. touching). - ANSWER Direct
_______ contact transmission requires contact with fomites (ex. a cup). - ANSWER
Indirect
_______ contact transmission is airborne (ex. coughing). - ANSWER Droplet
In ______ disease, symptoms develop rapidly. - ANSWER acute
In ______ disease, symptoms develop slowly. - ANSWER chronic
In ______ disease, symptoms develop between acute and chronic. - ANSWER subacute
In ______ disease, the disease displays no symptoms for a period of inactivity. - ANSWER
latent
Give an example of a latent virus - ANSWER Herpesvirus
To cause disease, all pathogens must: - ANSWER 1. enter a host
2. find their unique niche
3. evade immune defenses
4. multiply and eventually be transmitted to a new susceptible host
, Pathogens can be distinguished from their avirulent counterparts by the presence of
their _________ that help accomplish these goals. - ANSWER virulence factors.
What are Falkow's "Molecular Koch Postulates"? - ANSWER 1. The phenotype must
match the pathogenic strains of a species
2. Specific inactivation of a suspected virulence factor should lead to a measurable loss
in virulence
3. Reversion or replacement of the mutated gene should restore pathogenicity
Virulence genes may be found on ____________________ in the chromosome, on plasmids,
or even on phage genomes. - ANSWER pathogenicity islands
Pathogenicity islands contain clusters of virulence genes that were originally inherited
through ____________________ - ANSWER horizontal transmission
Pathogenicity islands are often flanked by ______ or ______ genes and have a _______
content that differs from the rest of the genome. - ANSWER phage; plasmid; GC
The first step of infection is ___________. - ANSWER attachment/adhesion
Bacteria attach to a host cell with _____ or _______ - ANSWER pili; adhesins
Adhesins are - ANSWER surface proteins that bind to a host cell
Viruses attach to their hosts through their ________ - ANSWER capsid or envelope
proteins
Bacteria can attach to surfaces in bulk, forming a _________ - ANSWER biofilm
How biofilms participate in chronic infections? - ANSWER They enable a persistent
adherence and resistance to the host and antimicrobial agents.
A ______ is a substance that contributes to pathogenicity - ANSWER toxin
A _______ is an inactivated toxin used in vaccines - ANSWER toxoid
An ________ is an antibody against a specific toxin - ANSWER antitoxin
What are the two main types of bacterial toxins? - ANSWER exotoxins and endotoxins
Exotoxins are _______ produces by bacteria to _______ host cells and unlock their _______
- ANSWER proteins; kill; nutrients
Endotoxins are part of the ______ of Gram-_______ bacteria that ________ the host's
immune systems to harmful levels. - ANSWER LPS; negative; hyperactivate
Membrane-disrupting toxins can be either _______ (lyse RED blood cells) or _______ (lyse
Complete Solution
Pathogenicity - ANSWER the ability to cause disease
Pathogen - ANSWER An organism that causes disease
Virulence - ANSWER the degree of pathogenicity
Virulence factors - ANSWER traits of a microbe that promote pathogenicity
Pathology - ANSWER the study of disease
Etiology - ANSWER The study of the cause of disease
Pathogenesis - ANSWER the development of disease
Infection - ANSWER the growing and multiplying of pathogens in the host
Disease - ANSWER an abnormal state in which the body is not functioning normally.
T/F: Infection always leads to disease - ANSWER False. Most infections are removed by
the immune system.
________ have the ability to penetrate host defenses. - ANSWER Primary pathogens
_________ cause disease only in compromised hosts. - ANSWER Opportunistic
pathogens
What does "ID50" stand for? - ANSWER Infectious dose of 50% of the test population
What ID50 value would be the most virulent? - ANSWER The smaller value, because it
requires a lower to dose to infect the same amount of people.
What does "LD50" stand for? - ANSWER Lethal dose of a toxin for 50% of the test
population
What LD50 value would be most virulent? - ANSWER The smaller value, because it
requires a lower to dose to kill the same amount of people.
_______ are considered a _______ of infection because they may have inapparent
infections or latent disease. - ANSWER Carriers; reservoir
A pathogen of _________ origin is one that mutated from an animal. - ANSWER zoonotic
Give an example of a human reservoir of infection pathogen - ANSWER STDs
Give an example of an animal reservoir of infection pathogen - ANSWER rabies, lyme
,disease
Give an example of a nonliving reservoir of infection pathogen - ANSWER botulism,
tetanus, anthrax
What would be a common nonliving reservoir of infection? - ANSWER Soil
What are the three portals of entry? (that's what she said) - ANSWER skin, mucous
membrane, parenteral route
What is meant by the parenteral route of infection? - ANSWER entering the blood stream
through injection such as needles, mosquitos, and ticks
Vehicle transmission is through _______ - ANSWER an inanimate reservoir, for example,
food or water.
Vector disease transmission occurs from _______ - ANSWER an animal host to human
host
Mechanical vector disease transmission occurs when _____ - ANSWER an arthropods
carries pathogens on their feet, such as flies carrying typhoid fever.
Biological vector disease transmission occurs when _______ - ANSWER the pathogen
reproduces within the vector, for example, lyme disease in ticks.
_______ contact transmission requires close associate between the infected host and
susceptible host (ex. touching). - ANSWER Direct
_______ contact transmission requires contact with fomites (ex. a cup). - ANSWER
Indirect
_______ contact transmission is airborne (ex. coughing). - ANSWER Droplet
In ______ disease, symptoms develop rapidly. - ANSWER acute
In ______ disease, symptoms develop slowly. - ANSWER chronic
In ______ disease, symptoms develop between acute and chronic. - ANSWER subacute
In ______ disease, the disease displays no symptoms for a period of inactivity. - ANSWER
latent
Give an example of a latent virus - ANSWER Herpesvirus
To cause disease, all pathogens must: - ANSWER 1. enter a host
2. find their unique niche
3. evade immune defenses
4. multiply and eventually be transmitted to a new susceptible host
, Pathogens can be distinguished from their avirulent counterparts by the presence of
their _________ that help accomplish these goals. - ANSWER virulence factors.
What are Falkow's "Molecular Koch Postulates"? - ANSWER 1. The phenotype must
match the pathogenic strains of a species
2. Specific inactivation of a suspected virulence factor should lead to a measurable loss
in virulence
3. Reversion or replacement of the mutated gene should restore pathogenicity
Virulence genes may be found on ____________________ in the chromosome, on plasmids,
or even on phage genomes. - ANSWER pathogenicity islands
Pathogenicity islands contain clusters of virulence genes that were originally inherited
through ____________________ - ANSWER horizontal transmission
Pathogenicity islands are often flanked by ______ or ______ genes and have a _______
content that differs from the rest of the genome. - ANSWER phage; plasmid; GC
The first step of infection is ___________. - ANSWER attachment/adhesion
Bacteria attach to a host cell with _____ or _______ - ANSWER pili; adhesins
Adhesins are - ANSWER surface proteins that bind to a host cell
Viruses attach to their hosts through their ________ - ANSWER capsid or envelope
proteins
Bacteria can attach to surfaces in bulk, forming a _________ - ANSWER biofilm
How biofilms participate in chronic infections? - ANSWER They enable a persistent
adherence and resistance to the host and antimicrobial agents.
A ______ is a substance that contributes to pathogenicity - ANSWER toxin
A _______ is an inactivated toxin used in vaccines - ANSWER toxoid
An ________ is an antibody against a specific toxin - ANSWER antitoxin
What are the two main types of bacterial toxins? - ANSWER exotoxins and endotoxins
Exotoxins are _______ produces by bacteria to _______ host cells and unlock their _______
- ANSWER proteins; kill; nutrients
Endotoxins are part of the ______ of Gram-_______ bacteria that ________ the host's
immune systems to harmful levels. - ANSWER LPS; negative; hyperactivate
Membrane-disrupting toxins can be either _______ (lyse RED blood cells) or _______ (lyse
