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The idea that communicable diseases were caused by the passage of living things from one person to another was first put forth by

Fracastorius.

The connection between a particular organism and a specific disease was first made by

KOCH

The series of steps used to connect an organism to a disease are known as

Koch's postulates.

The interaction of all organisms within a biological community is called a(n)

ECOSYSTEM

The microorganisms that are regularly found in or on the body, yet do no apparent harm are called

NORMAL FLORA

The microorganisms that are occasionally found in or on the body are called

TRANSIENT FLORA

Organisms that are found together and interact on a more or less permanent basis are in a relationship termed

SYMBIOSIS

The symbiotic relationship wherein both partners benefit is termed

MUTUALISM

A relationship in which one partner benefits and the other is unaffected is termed

COMMENSALISM

A relationship in which one partner benefits and the other is harmed is termed

PARASITISM

The resident microbial population of the human fetus is

ZERO

Which of the following is true about the role normal flora play in maintaining host health?

THEY PROVIDE A SURFACE THAT IS INCOMPATIBLE FOR ATTACHMENT OF AN INVADER, THEY ESTABLISH COMPETITION FOR NUTRIENTS AND VITAMINS, THEY PRODUCE ANTIMICROBIAL SUBSTANCES, AND THEY STIMULATE THE IMMUNE SYSTEM

Which of the following members of the normal flora inhibits the growth of Corynebacterium diphtheriae by producing hydrogen peroxide?

Streptococcus species.

Which of the following members of the normal flora inhibits the growth of bacteria by production of fatty acids from lipids?

Staphylococcus epidermidis AND Propionibacterium species.

Which of the following may inhibit the activity of normal flora and allow pathogens to become established?

ANTIBODIES

A diet high in meat leads to a population of normal flora with an increased number of

BACTEROIDES SPECIES

Growth of a parasitic organism in or on the host is referred to as

INFECTION

A disease-causing microorganism or virus is referred to as a(n)

PATHOGEN

OPPORTUNIST

take advantage of special circumstances.

A member of the normal flora that becomes an opportunist if it invades the urinary bladder is

E. COLI

An obligate intracellular pathogen may

may only survive and grow inside a cell.

Attributes of an organism that promote pathogenicity are called

VIRULENCE FACTORS

Avirulent organisms are

UNABLE TO CAUSE DISEASE

Which of the following may be considered virulence factors?

ADHESINS, CAPSULES, ENDOTOXINS AND PROTEASES

Which of the following does S. pneumoniae use to survive in the host?

CAPSULES

Which of the following would be considered a sign of a disease?

fever of 39 °C

People who carry and may spread pathogenic organisms without any overt symptoms of illness are called

CARRIERS

The spread of toxin via the circulation is called

TOXEMIA

If a disease affects only a human and not an animal, then it would be difficult to fulfill Koch's postulate number

3

A more modern equivalent to Koch's Postulates is termed

Molecular Postulates.

Transmission of an infectious disease by touching, handshaking, or kissing is considered

DIRECT CONTACT

Which of the following is considered an indirect mode of transmission?

INSECTS BITES

Fomites are involved in

indirect contacts.

The number of organisms necessary to insure infection is termed the

INFECTIOUS DOSE

The portal of entry

plays a role in whether an infection will be established, may be the skin or respiratory tract AND may be the same as the portal of exit.

The first step in the establishment of infection is that the organism must

ATTACH THE HOST CELLS

Which of the following factors is not considered important for the establishment of an infection?

TOXICITY

Typically, adhesins

ARE FOUND ON PILI, HELP BACTERIA ATTACH TO HOST CELLS AND ARE PROTEINS

The process by which infectious agents are ingested by host cells is termed

ENDOCYTOSIS

Density-dependent expression of virulence factors is called

quorum sensing.

C5a peptidase

is a virulence factor.

The chemical nature of endotoxins is that of a

lipopolysaccharide.

The chemical nature of exotoxins is that of a

PROTEIN

Which of the following is/are true about endotoxins?

Lipid A is the toxic portion of the molecule.

The lack of susceptibility to diseases of other species in humans may be due to the

lack of receptors that are recognized by adherence factors.

Bacteria may survive phagocytosis by

preventing fusion of the lysosome with the phagosome AND preventing acidification of the phagolysosome.

Which is true about superantigens?

They are a type of exotoxin AND They bind to MHC class II antigen on T cells.

Which is/are true of viruses?

They may suppress the production of MHC Class I protein, They may produce an MHC Class I mimic protein AND They may prevent cell suicide.

An example of genetic variation used in pathogen survival may be

changing the pilus type.

Which is true about botox?

It may cause botulism AND It is useful in treating conditions related to muscle contractions.

In Gram-negative bacteria many of the genes required for pathogenicity are

located close together on chromosomes in regions called pathogenicity islands.

Microbes may evade host defensive responses by

mimicking host materials.

The most successful parasites are the ones that live in harmony with their hosts.

TRUE

A human fetus has no resident microbial population.

TRUE

Infection always leads to disease.

FALSE

A disease is an infection that impairs the normal state of health.

TRUE

Obligate intracellular parasites may be grown in special synthetic media.

FALSE

During incubation and convalescence a person may still spread infectious organisms.

TRUE

The infectious dose of most pathogens is about equal.

FALSE

A strong attachment of a microorganism to a host cell automatically leads to disease.

FALSE

High concentrations of some bacteria are necessary for successful invasion because only at high density are their virulence genes expressed.

TRUE

Only Gram-positive bacteria produce exotoxins.

FALSE

What reason could there be for some people to doubt that HIV is the causative agent of AIDS?

Koch's postulates have been used to make a connection between particular organisms and specific diseases. However, there are limitations to the use of the postulates. Koch's postulate #3 requires innoculating the host with the potential pathogen. Obviously, this is not possible for diseases only found in humans. This barrier may sometimes be circumvented if there is a good animal model. There is no real good animal model for AIDS. With no good animal model, it is not possible to make the direct connection between organism and disease, and one has to rely on indirect connections.

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