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
cleavage of rRNA that results in disruption of ribosome function
ADP ribosylation of guanylate cyclase that stimulates production of cGMP
ADP ribosylation of adenylate cyclase that stops production of cAMP

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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
survive the acid pH of the stomach
secrete LT (heat labile toxin) and ST (heat stable toxin) into the lumen of the intestine
survive within macrophages

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

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

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Microorganisms and Disease
What is common in catheters and ventilators?

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
They bypass important defenses of the body

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Microorganisms and Disease
Prontosil is

an effective antibacterial when used in animals
an effective antibacterial both in animals as well as in in-vitro cultures
an effective antibacterial when used in in-vitro cultures
not used as an antibacterial agent

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