Microorganisms and Disease
The influenza vaccine is administered each year because

the vaccine is sufficiently toxic to make it necessary to administer only a small amount at any one time
None of these
mutations in the viral hemagglutinin may allow the virus to evade the immune response elicited by previous vaccines
it is a polysaccharide vaccine that does not confer long-term protection

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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
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

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

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Microorganisms and Disease
Prontosil is

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

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