Unit 7 Flashcards
How does bacteria inject proteins into the epithelial cell?
with Invasins
What do these proteins injected into the epithelial cell cause?
Rearrangement of the actin in its cytoskeleton;
Causes membrane to ruffle and the bacteria to be engulfed
What feature of Salmonella prevent it from being phagocytosed?
Flagella
Where do Salmonella pathogens grow and replicate in the infected host?
Inside phagocytes
Where is the site of Shigella attachment in the host?
M cells
How do Shigella cells move between host cells?
They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another
What is the etiologic agent of typhoid?
Salmonella
While investigating a newly discovered Gram-negative bacterium, you find that when the bacteria die, the host experiences severe fever and inflammation. You suspect that the bacterium has __________ in its outer wall membrane.
lipid A
A new drug blocks the adhesins on the surface of a bacterial pathogen. What would likely be the major effect of this drug?
It will prevent infection by this pathogen;
Without adhesins to help them attach to host cells and tissues, pathogens generally cannot resist the defenses of the body long enough to cause an infection or disease.
The suspect agent…
(regarding the demonstration of the etiology of disease)
- must be able to be reisolated from the infected experimental host
- must be isolated and cultured in the laboratory
- must be present in all cases of the disease
- must cause the disease under investigation when introduced into a susceptible host organism
Among the virulence factors produced by Staphylococcus aureus are hemolysin, coagulase, hyaluronidase, and enterotoxin. What factor contribute. to the ability of S. aureus to invade the body?
hyaluronidase
enterotoxin
coagulase
hemolysin
coagulase and hemolysin
hyaluronidase;
an enzyme that breaks down hyaluronic acid, a component of the extracellular matrix, which allows Staphylococcus aureus to spread and invade deeper tissues.
What virulence factors play roles in immune evasion and tissue damage?
coagulase and hemolysin; rather than in direct invasion
What do Coagulase and hemolysin do?
Coagulase: helps form blood clots to protect the bacteria from immune cells
Hemolysin: lyses red blood cells to obtain nutrients
What is Chemotaxis?
The movement of a cell towards or away from a chemical stimulus
What do phagocytes use to move toward microorganisms or damaged cells at the site of infection?
Pseudopods;
often arriving only minutes after infection
Describe adherence
When the plasma membrane of phagocytes attaches to the glycoproteins on the microorganisms surface;
Made easier through Opsonization
What is Opsonization?
A process in which antibodies or complement proteins from the host cell coat the microbes surface serving as “handles”’
Proteins that coat the microbe: Opsonins
Phagolysosome
The structure that results from the fusion of a phagosome and a lysosome
Digestion of most bacteria is complete within ____
10-30 min
Exocytosis is ____
when the phagolysosome fuses with the plasma membrane and expels its contents
What does the plasma membrane of a phagocyte attach to on a microorganism?
Glycoproteins
The process by which a phagocyte moves toward a chemical signal at the site of an infection is called ____
Chemotaxis
What phagocytic processes occurs last in the sequence?
Exocytosis
What is the role of opsonins?
They create “handles” that make it easier for the pseudopods of phagocytes to attach to the microbe invader
How is Streptococcus pneumoniae able to avoid destruction by a phagocyte?
Their capsules make them “slippery” to phagocytes
Which microorganism requires the low pH inside a phagolysosome in order to reproduce?
Coxiella burnetii
What microorganism uses M protein to avoid destruction of a phagocyte?
Streptococcus pyogenes
What is the complement system?
A set of proteins that circulate in the blood serum;
When activated the proteins work together to destroy foreign cells by cytolysis to activate the inflammatory response and assist in phagocytosis
What are the main components of the complementary system called?
C1 through C9