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Define pathogenicity in the context of bacteria.
Define pathogenicity in the context of bacteria.
Pathogenicity is the ability of any bacterial species to cause disease in a susceptible human host.
What distinguishes opportunistic pathogens from other pathogens?
What distinguishes opportunistic pathogens from other pathogens?
Opportunistic pathogens can cause disease primarily in immunocompromised individuals, whereas they rarely cause disease in healthy people.
Explain the term virulence.
Explain the term virulence.
Virulence refers to the degree to which a pathogen can cause disease, ranging from low to high levels.
Give an example of a bacterium with high virulence and its associated disease.
Give an example of a bacterium with high virulence and its associated disease.
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What are the three epidemiological terms defined in the text?
What are the three epidemiological terms defined in the text?
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Describe the first stage of infection.
Describe the first stage of infection.
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What role do bacterial pili play in infection?
What role do bacterial pili play in infection?
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What is meant by a disease being endemic?
What is meant by a disease being endemic?
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What is the significance of the host response in the stages of infection?
What is the significance of the host response in the stages of infection?
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How does moderate virulence manifest in Escherichia coli?
How does moderate virulence manifest in Escherichia coli?
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Study Notes
Pathogenicity
- Pathogenicity is the ability of a bacterial species to cause disease in a susceptible human host.
- A pathogen is a bacterial species that can cause disease when presented with favorable circumstances.
- Opportunistic pathogens are bacterial species that rarely cause disease in immunocompetent people but can cause serious infection in immunocompromised patients and are frequent members of the body's normal flora.
Virulence
- Virulence is a term that presumes pathogenicity and allows expression of degrees from low to extremely high.
- Examples of virulence include:
- Low virulence: Streptococcus salivarius, which is universally present in the oropharyngeal flora of humans and can cause disease only in specific circumstances, such as when it lands on a damaged heart valve.
- Moderate virulence: Escherichia coli, which is universally found in the colon but can cause acute infection if displaced to other sites.
- High virulence: Bordetella pertussis, which is highly infectious and causes disease in almost every nonimmune person it contacts.
Epidemiology Terms
- Epidemic: an infection that occurs more frequently than usual.
- Pandemic: an epidemic with a worldwide distribution.
- Endemic: an infection that is constantly present at a low level in a specific population.
Stages of Infection
- Transmission: infection from an external source into the portal of entry.
- Evasion: evasion of primary host defenses such as skin or stomach acid.
- Adherence: adherence to mucous membranes, usually by bacterial pili.
- Colonization: growth of the bacteria at the site of adherence.
- Disease: disease caused by toxin production or invasion, accompanied by inflammation.
- Host Response: host response with nonspecific and specific (immunity) defenses.
- Progression or Resolution: progression or resolution of the disease.
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Description
Understand the key concepts of pathogenicity and virulence in bacteriology, including opportunistic pathogens and their impact on human health.
