Microbiology: Pathogens and Virulence Factors

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What is the primary requirement for pathogens to replicate in a host?

Susceptibility of the host to the pathogen
High infectious dose of the pathogen
Presence of virulence factors
Favourable conditions within the host (correct)

Where do intracellular pathogens grow and multiply?

Outside of host cells
Within host cells (correct)
In both within and outside host cells
In blood and tissue fluids

What determines the degree of damage caused by a pathogen?

Virulence factors (correct)
Infectious dose of the pathogen
Pathogenicity of the pathogen
Susceptibility of the host

What is the ability of a microbe to cause disease?

Pathogenicity (D) Signup and view all the answers

What is the term for the ability of a pathogen to spread to adjacent tissues?

Invasiveness (B) Signup and view all the answers

What type of pathogens can grow both within and outside of host cells?

Facultative intracellular pathogens (C) Signup and view all the answers

What is the term for the ability of a pathogen to adhere to host cells or tissues?

Adherence (A) Signup and view all the answers

What is the term for the process by which pathogens spread from the inoculation site to deeper tissues?

Passive penetration (B) Signup and view all the answers

What is the term for the ability of a pathogen to cause localised infections?

Colonisation (C) Signup and view all the answers

What is the term for the production of specific products and/or enzymes that promote spreading of pathogens?

Passive penetration (A) Signup and view all the answers

What is the primary characteristic of superantigens?

They stimulate T-cells to release cytokines and can trigger a cytokine storm (C) Signup and view all the answers

What is the main difference between exotoxins and endotoxins?

Exotoxins are heat-labile, while endotoxins are heat-stable (A) Signup and view all the answers

What is the role of nutrition in host susceptibility to infection?

It affects the immune system's ability to respond to infection (D) Signup and view all the answers

What is the term for the number of pathogens required to infect 50% of an experimental group of hosts?

Infectious dose 50 (C) Signup and view all the answers

What is the term for the period after pathogen entry, before signs and symptoms appear?

Incubation period (C) Signup and view all the answers

What is the primary way in which pathogens evade the immune system?

By evolving strategies to evade or interfere with the immune response (A) Signup and view all the answers

What is the term for the component of the pathogen's cell wall that can trigger septic shock?

Lipid A (B) Signup and view all the answers

What is the term for the stage of disease where signs and symptoms are most severe?

Period of illness (C) Signup and view all the answers

What is the role of genetic predisposition in host susceptibility to infection?

It affects the immune system's ability to respond to infection (D) Signup and view all the answers

What is the term for the stage of disease where signs and symptoms begin to disappear?

Convalescence (A) Signup and view all the answers

What is a characteristic shared by most exotoxin producers?

They are Gram-negative bacteria that have toxin genes in their plasmids or prophage DNA (B) Signup and view all the answers

What is the primary function of neutralising antibodies against exotoxins?

To neutralise the toxin and prevent its effects (B) Signup and view all the answers

What is the mechanism by which superantigens exert their effects?

By stimulating T-cells to release cytokines (A) Signup and view all the answers

What is the primary difference between the infectious dose 50 and the lethal dose 50?

The infectious dose 50 is the dose that infects 50% of experimental animals, while the lethal dose 50 is the dose that kills 50% of experimental animals (C) Signup and view all the answers

What is the primary role of the immune system in preventing disease?

To eliminate most microbes before they can cause disease (B) Signup and view all the answers

What is the primary way in which pathogens disseminate within the host?

Through the bloodstream (A) Signup and view all the answers

What is the primary determinant of the degree of damage caused by a pathogen?

The combination of the pathogenicity of the microbe and the defence mechanisms of the host (B) Signup and view all the answers

What is the primary function of endotoxins?

To exert effects in the host when the pathogen lyses or divides (B) Signup and view all the answers

What is the primary role of sanitation in preventing disease?

To reduce the number of pathogens in the environment (C) Signup and view all the answers

What is the primary characteristic of the prodromal stage of disease?

The signs and symptoms are not clear enough for diagnosis (D) Signup and view all the answers

What is the primary reason why pathogens must find favourable conditions in the host?

To replicate and cause disease (C) Signup and view all the answers

What is the main difference between facultative and obligate intracellular pathogens?

Their ability to grow outside of host cells (A) Signup and view all the answers

What is the role of virulence factors in determining the degree of disease caused by a pathogen?

They affect the severity of the disease (A) Signup and view all the answers

What is the primary way in which pathogens establish a localised infection?

Through the adherence of pathogens to host cells (B) Signup and view all the answers

What is the term for the ability of a pathogen to spread to adjacent tissues beyond the initial site of infection?

Invasiveness (C) Signup and view all the answers

What is the primary role of lytic substances produced by pathogens during active penetration of host tissue?

To degrade carbohydrate-protein complexes between cells (A) Signup and view all the answers

What is the primary difference between the growth of extracellular and intracellular pathogens?

The location of growth, either inside or outside of host cells (A) Signup and view all the answers

What is the role of adherence to host cells or tissues in the pathogenesis of disease?

It allows for colonisation of the host (B) Signup and view all the answers

What is the primary reason why some pathogens are able to establish a systemic infection?

Their ability to disseminate widely around the body (C) Signup and view all the answers

What is the primary characteristic of the interaction between pathogens and the host that determines the outcome of infection?

The balance between the pathogen's virulence and the host's susceptibility (D) Signup and view all the answers