Microorganisms and Disease
The influenza vaccine is administered each year because

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

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Microorganisms and Disease
What is common in catheters and ventilators?

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
They predispose patients to viral rather than bacterial infections

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Microorganisms and Disease
The "A" subunit of diphtheria toxin

forms cAMP that leads to fluid accumulation
lysis macrophages with the release of cytokines
binds host cell receptors found on heart cells
cause ADP ribosylation of a factor involved in protein synthesis

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Microorganisms and Disease
Prontosil is

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

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