Chp 15 Part II Flashcards
What is virulence?
The tendency of a pathogen to cause damage/disease to the host.
What makes one bacterium more virulent than another?
The presence or absence of virulence factors.
Give an example of a highly virulent bacterium.
Staphylococcus aureus.
What are virulence factors?
Any pathogenic attribute that promotes colonization, immunoevasion, or obtaining nutrition from the host.
What are examples of virulence factors?
Adhesion factors, exoenzymes, toxins, and antiphagocytic factors.
What is adhesion in microbial pathogenesis?
The process by which microorganisms attach themselves to cells.
Why is adhesion important?
It is required to establish colonies successfully within the host.
What are adhesion factors?
Specialized structures like ligands that bind to host cell receptors.
What happens if a microorganism cannot make adhesins?
It becomes avirulent and cannot establish infection.
What are exoenzymes?
Extracellular enzymes released by pathogens to break down host structures and evade defenses.
Give two examples of exoenzymes.
Hyaluronidase and collagenase.
What does hyaluronidase do?
Digests hyaluronan, the ‘glue’ that holds animal cells together.
What does collagenase do?
Breaks down collagen, a major structural protein in the body.
What are bacterial toxins?
Chemicals that harm tissues or trigger immune responses that cause damage.
What is toxemia?
The presence of toxins in the bloodstream.
What are the two types of bacterial toxins?
Exotoxins and endotoxins.
What is an exotoxin?
A toxin secreted by bacteria that can cause severe damage.
What are the three types of exotoxins?
Cytotoxins, neurotoxins, and enterotoxins.
What is the function of cytotoxins?
They kill host cells or affect their function.
What do neurotoxins target?
They specifically interfere with nerve cell function.
What do enterotoxins affect?
They affect cells lining the gastrointestinal tract.
What is an A-B toxin?
A type of exotoxin where the A component is active and the B component binds to the host cell.
Give an example of an A-B toxin.
Botulinum toxin produced by Clostridium botulinum.
How does botulinum toxin affect the body?
It prevents muscle contraction, causing flaccid paralysis.
What are endotoxins composed of?
Lipopolysaccharides (LPS) from the outer membrane of Gram-negative bacteria.
What is the toxic component of endotoxin?
Lipid A.
What symptoms can endotoxins cause?
Fever, inflammation, diarrhea, hemorrhaging, shock, and blood coagulation.
How are endotoxins released?
When Gram-negative bacteria die and their cell walls break apart.
What is the pyrogenic response?
A fever-inducing mechanism triggered by endotoxins.
What are antiphagocytic factors?
Factors that prevent phagocytosis by host immune cells.
Why do some bacteria have capsules?
Capsules help bacteria evade immune cells by making them hard to recognize or engulf.
What is antigenic variation?
A mechanism where pathogens alter their surface proteins to evade the immune system.
Which bacterium uses antigenic variation through homologous recombination?
Neisseria gonorrhoeae.
What is bacterial gastroenteritis?
Inflammation of the stomach or intestines caused by bacteria, often due to contaminated food or water.
What is the primary transmission route for bacterial gastroenteritis?
Fecal-oral route.
Which bacterium causes cholera?
Vibrio cholerae.
What is the main virulence factor of Vibrio cholerae?
Cholera toxin, an A-B toxin.
What are ‘rice-water stools’?
Watery diarrhea characteristic of cholera infection.
How does cholera toxin affect the body?
It activates chloride channels, leading to rapid water loss and dehydration.
What is STEC?
Shiga toxin-producing E. coli.
What are symptoms of STEC infection?
Diarrhea, severe cramping, and sometimes hemolytic uremic syndrome (HUS).
What is HUS?
A condition where damaged red blood cells build up in the kidneys, potentially leading to kidney failure. Also a potential symptoms of STEC.
How is STEC transmitted?
Mostly through contaminated food, especially undercooked beef.
What is Clostridium difficile (C. diff) infection associated with?
Antibiotic use, which disrupts normal gut microbiota.
What are symptoms of C. diff infection?
Watery diarrhea, colitis, and in severe cases, pseudomembranous colitis.
What are the two main toxins of C. diff?
Toxin A (causes fluid loss) and Toxin B (kills colon cells).
Why is C. diff difficult to control in hospitals?
It forms endospores, allowing it to survive harsh conditions.
How can bacterial gastroenteritis be prevented?
Proper food handling, sanitation, and clean water sources.
What is septicemia?
A severe bloodstream infection where bacteria multiply in the blood, leading to shock.
Types of virulence factors
Endotoxin, exotoxin, antiphagocytosis, antigenosis, exoenzymes
