Bacterial Pathogenesis and Toxins

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Questions and Answers

Pathogenicity is the ability of an organism to ______________ a host and cause disease.

infect

The severity of the disease in infected hosts is referred to as ______________.

virulence

Microbes that colonize the body and usually do not cause disease are referred to as ______________ flora.

normal

The ability of a pathogen to invade and establish itself within the host is referred to as ______________.

aggressiveness Signup and view all the answers

Microorganisms that live on another living organism or inanimate object without causing disease are referred to as ______________ flora.

normal Signup and view all the answers

______ establishment of infection by bacterial pathogens requires adhesion to host cells, colonization of tissues, and in certain cases, cellular invasion—followed by intracellular multiplication, dissemination to other tissues, or persistence.

Successful Signup and view all the answers

Toxins are a very specific ______ factor produced by some bacterial pathogens, in the form of substances that are poisonous to the host.

virulence Signup and view all the answers

Exotoxins are heat-sensitive soluble ______ that are released into the surrounding environment by a living organism.

proteins Signup and view all the answers

Type I exotoxins are ______-active – these toxins bind to cell receptors and stimulate cell responses.

cell surface Signup and view all the answers

Type II exotoxins exert their effect on the host cell ______, often by forming pores in the membrane of the target cell.

membrane Signup and view all the answers

Brushing teeth is linked to the lower risks of atrial fibrillation and ______.

HF Signup and view all the answers

Host-pathogen interaction is defined as how microbes sustain themselves within host organisms on a molecular, cellular, organismal or ______ level.

population Signup and view all the answers

Bacterial pathogens express a wide range of molecules that bind host cell targets to facilitate a variety of different host ______.

responses Signup and view all the answers

Host-pathogen interactions can be classified into two types: ______ and indirect.

direct Signup and view all the answers

The molecular strategies used by bacteria to interact with the host can be unique to specific pathogens or ______ across several different species.

conserved Signup and view all the answers

A ______ pathogen infects a host that is compromised in some way.

opportunistic Signup and view all the answers

The human body is not ______ at birth, but becomes colonized by bacteria.

sterile Signup and view all the answers

Streptococcus pneumoniae is commonly found in the ______ respiratory tract.

upper Signup and view all the answers

A breach in the body’s natural defenses creates a ______ of entry for bacteria.

portal Signup and view all the answers

Knowledge of normal flora helps predict the ______ causing infection in specific body sites.

pathogens Signup and view all the answers

The A subunit of the toxin will cleave the cellular ______ resulting in a decrease in neurotransmitter release.

synaptobrevin Signup and view all the answers

Endotoxins are made by Gram negative bacteria, as a component of the outer membrane of their cell wall containing ______.

lipopolysaccharide Signup and view all the answers

The transmission of microorganisms can be divided into routes, regardless of the ______, transmission must occur for an infection to spread.

reservoir Signup and view all the answers

Contact transmission includes direct contact, such as touching, kissing, sexual intercourse, or droplet sprays, and indirect contact - involves inanimate objects called ______.

fomites Signup and view all the answers

A massive release of ______ in a host can cause endotoxin shock, which can be deadly.

endotoxin Signup and view all the answers

Study Notes

Pathogenicity and Virulence

Successful establishment of infection by bacterial pathogens requires adhesion to host cells, colonization of tissues, and in certain cases, cellular invasion, followed by intracellular multiplication, dissemination to other tissues, or persistence.

Toxins

Toxins are a very specific virulence factor produced by some bacterial pathogens, in the form of substances that are poisonous to the host.
Toxigenicity refers to an organism’s ability to make toxins.
There are two categories of toxins: exotoxins and endotoxins.

Exotoxins

Exotoxins are heat-sensitive soluble proteins that are released into the surrounding environment by a living organism.
There are three categories of exotoxins:
- Type I: cell surface-active – bind to cell receptors and stimulate cell responses.
- Type II: membrane-damaging – exert their effect on the host cell membrane, often by forming pores in the membrane of the target cell.
- Type III: intracellular – gain access to a particular host cell and stimulate a reaction within the target cell.

Endotoxins

Endotoxins are made by Gram-negative bacteria, as a component of the outer membrane of their cell wall.
Endotoxins can cause endotoxin shock, which can be deadly.

Pathogenicity vs. Virulence

Pathogenicity is the ability of an organism to infect a host and cause disease.
Aggressiveness is the ability of the pathogen to invade and establish itself within the host.
Virulence is the severity of the disease in infected hosts (or degree of pathogenicity).

Ecological Relationship

Normal flora: microbes that colonize the body and usually do not cause disease.
Opportunistic pathogens: microbes that normally do not cause disease, but may under certain circumstances.

Host-Pathogen Interaction

Host-pathogen interaction is defined as how microbes sustain themselves within host organisms on a molecular, cellular, organismal, or population level.
Routes of transmission include direct contact, droplet transmission, and indirect contact.

Mechanisms of Pathogenicity

Bacterial pathogens express a wide range of molecules that bind host cell targets to facilitate a variety of different host responses.
The molecular strategies used by bacteria to interact with the host can be unique to specific pathogens or conserved across several different species.

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Description

Learn about the process of bacterial infection, including adhesion, colonization, and cellular invasion, as well as the role of toxins in pathogenesis.