Microorganisms and Disease
Cholera toxin is an A-B type toxin in which the B portions bind to a receptor on a host cell and the A portion enters the cell to cause

ADP ribosylation of a G protein that locks it into an active form that stimulates adenylate cyclase to make cAMP
ADP ribosylation of guanylate cyclase that stimulates production of cGMP
ADP ribosylation of adenylate cyclase that stops production of cAMP
cleavage of rRNA that results in disruption of ribosome function

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Microorganisms and Disease
Type III secretion systems are used to inject "effector" proteins directly into a host cell. Salmonella uses a type III secretion system to help the pathogen to

activate T cells to proliferate and secrete cytokines
secrete LT (heat labile toxin) and ST (heat stable toxin) into the lumen of the intestine
survive the acid pH of the stomach
survive within macrophages

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Microorganisms and Disease
Plastic implants can pose a serious nosocomial infection problem because

infected implants usually have to be surgically removed
phagocytes have trouble moving on the plastic surface
All of these
phagocytes have trouble engulfing bacteria embedded in a biofilm

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Microorganisms and Disease
What is common in catheters and ventilators?

They bypass important defenses of the body
They predispose patients to viral rather than bacterial infections
They are used primarily in neonatal intensive care units
Bacteria responsible for associated infections are usually susceptible to antibiotics

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