Microbial Pathogenesis Flashcards
What is microbial pathogenesis?
The study of how pathogens infect and cause disease, including interactions with the immune system and virulence factors.
What are pathogens?
Organisms that cause disease.
True or False: All microbes are pathogenic.
False
The vast majority of microbes have neutral or beneficial interactions with humans.
What is pathogenesis?
The mechanism that leads to disease.
Define virulence.
A term often used to describe the severity of disease caused by a pathogen.
What is an opportunistic pathogen?
An organism that is often non-pathogenic but becomes a pathogen under certain circumstances.
What are phytopathogens?
Microbial pathogens that affect plants.
What is an example of a bacterial phytopathogen?
Erwinia amylovora, which causes fire blight in apple and pear trees.
What fungal pathogen caused the Gros Michel banana to go extinct?
Fusarium oxysporum.
What is infection?
The invasion of the body by a disease-causing organism.
What is the difference between infection and disease?
Infection refers to the presence of a pathogen, while disease is damage or injury to the host organism with overt symptoms.
What is inflammation?
The body’s immune response to infection or injury.
What role does the immune system play in microbial infections?
It prevents and clears microbial infections.
Fill in the blank: The ability of a pathogen to enter host cells and/or tissues is called _______.
Invasion.
What are common stages of infections?
- Adherence
- Colonization
- Invasion
- Spread
What are virulence factors?
Molecules (typically proteins) produced by a pathogen that contribute to its ability to cause disease.
What is the function of adherence factors?
They help microbes bind to specific host cells/tissues to establish infection.
What is a major consequence of excessive inflammation?
It can lead to effects ranging from mild to life-threatening.
True or False: All symptoms of bacterial diseases come from the pathogen’s activities.
False
Some symptoms are caused by the immune response to the pathogen.
What is the role of secreted enzymes in virulence?
They can free up nutrients, damage host cells, and disrupt barriers to enable pathogen invasion/spread.
What is a Type III secretion system (T3SS)?
A mechanism used by some pathogens to inject specific effector proteins into host cells.
What disease is caused by S. Typhi?
Typhoid fever.
What are siderophores?
Secreted molecules that capture iron from the environment to aid in nutrient acquisition by pathogens.
What is an example of a pathogen that produces a capsule?
Streptococcus pneumoniae.
What is the significance of mucous membranes in microbial infections?
They are protective layers that line body access points and are common sites where infections are initiated.
What are exotoxins?
Secreted protein toxins that are important virulence factors.
What is the primary role of exotoxins in bacterial pathogens?
They target host cells and contribute to the virulence of the bacteria.
True or False: All bacterial pathogens produce toxins.
False
What is an example of a bacterial toxin?
⍺-toxin from Staphylococcus aureus.
How does ⍺-toxin from Staphylococcus aureus affect host cells?
It polymerizes in the host cell membrane to form a pore, causing effects like cell lysis.
What are AB-type toxins?
Toxins that consist of an A subunit, which exerts a biological effect, and B subunit(s), which bind to host cell receptors.
Fill in the blank: The A subunit of AB-type toxins typically modifies or degrades a specific _______.
host cell protein.
What is an example of an AB-type toxin?
Botulinum toxin.
Which bacterium produces botulinum toxin?
Clostridium botulinum.
What is the effect of botulinum toxin on the human body?
It cleaves specific SNARE proteins required for the release of acetylcholine, leading to muscle paralysis.
What is the lethality of botulinum toxin?
0.1 μg of toxin is enough to kill.
What role do toxins play in disease and therapeutics?
They are key in virulence and can be targeted for treatments and vaccines.
What is a toxoid?
An inactivated toxin used as a vaccine.
True or False: Toxins can be used to treat non-bacterial diseases.
True
What is Botox an example of?
The therapeutic use of botulinum toxin.
What is the causative agent of the plague?
Yersinia pestis.
What type of organism is Yersinia pestis?
A Gram-negative Proteobacterium.
Which animals primarily host Yersinia pestis?
Rodents.
How is Yersinia pestis primarily spread?
By fleas that bite rodents and can also bite humans.
What was the most severe pandemic caused by the plague?
The Black Death.
What are the three forms of plague caused by Yersinia pestis?
- Bubonic plague
- Pneumonic plague
- Septicemic plague
Which form of plague is the most common?
Bubonic plague.
What is the mortality rate of untreated pneumonic and septicemic plague?
Approximately 100%.
How did Yersinia pestis evolve?
Evolved from Yersinia pseudotuberculosis within the last 5,000-10,000 years.
What is a significant virulence factor of Yersinia pestis?
The F1 capsule, which inhibits uptake by the immune system.
What role does the T3SS play in Yersinia pestis virulence?
It secretes effector proteins that disrupt immune system function.
What is the significance of gene loss in Yersinia pestis?
Loss of the flagellum contributes to stealth and evasion of the immune system.
