Deck 2: Host-Parasite Interaction

Question 1

A laboratory professional is testing a new antimicrobial soap.The tech washes her forearm then does a culture of the skin.Which organisms should she most likely expect to find growing in the culture?

A)Diphtheroids and Bacillus spp.
B)Staphylococcus epidermidis and Propionibacterium
C)S.aureus and Propionibacterium
D)Diphtheroids and Propionibacterium
E)None of these organisms should be found.

Answer 1

B
Superficial antisepsis of the skin does not kill the Propionibacterium and S.epidermidis that live in the hair follicles and sebaceous glands.Diphtheroids are found in moist areas such as the axillae and toes.S.aureus is typically a pathogen but can be found on healthy skin.Propionibacterium colonizes the deep sebaceous glands.Handwashing does not remove all bacteria from the skin.

Question 2

All the following are potentially pathogenic organisms found in the nasopharynx of healthy individuals except:

A)Haemophilus influenzae.
B)Streptococcus pneumoniae.
C)Streptococcus mutans.
D)Neisseria meningitidis.

Answer 2

C
S.mutans is considered normal or resident flora of the oral and nasopharynx of healthy individuals.M.catarrhalis is resident flora of the oropharynx and is an opportunistic pathogen.H.influenzae, S.pneumoniae, and N.meningitides are all potential pathogenic.

Question 3

A patient with an indwelling catheter develops a fever and lethargy.In addition, the urine in the catheter bag has turned a brownish color and smells foul, which suggests an infection is present.What type of infection does this describe?

A)Opportunistic
B)Iatrogenic
C)Pathogenic
D)Parasitic

Answer 3

B
An iatrogenic infection occurs as the result of medical treatment or procedures.In this case, the use of an indwelling catheter to treat a medical condition has resulted in an infection.An opportunistic infection occurs when a host's condition changes and resident flora are able to cause disease.Pathogenic describes the types of organisms that cause disease, but not a type of infection.A parasitic infection occurs when an organism invades a host and only the organism benefits from the biologic relationship.

Question 4

The human body is constantly challenged by pathogens in the environment.It is not infected by every pathogen it encounters because the microbial flora:

A)engulf the pathogenic bacteria.
B)produce conditions at the microenvironmental level that block colonization.
C)prime our immune system.
D)activate and support the action of antigen-presenting cells, cytokines, and cell-mediated immunity.

Question 5

What type of bacteria is able to live in the colon with little to no oxygen and is the predominant organism?

A)Anaerobes
B)Facultative anaerobes
C)Facultative gram-negative rods
D)Gram-positive cocci

Question 6

The most common bacterial characteristic that allows for evasion of phagocytosis by the host is called:

A)exotoxin production.
B)extracellular enzyme production.
C)pili.
D)polysaccharide capsule.

Question 7

After perforation of the colon, surgeons must guard against infection in the _____ because of leakage of the contents of the colon.

A)peritoneal cavity
B)urinary bladder
C)vaginal flora
D)renal vein

Question 8

Organisms that participate in a biologic relationship where both benefit from one another are called:

A)parasites.
B)symbionts.
C)hosts.
D)flora.

Question 9

The smaller the number of microorganisms necessary to cause infection in a competent host, the more _____ the microorganism.

A)opportunistic
B)parasitic
C)invasive
D)virulent

Question 10

What is the name of the bacterial state that occurs when a host harbors a disease-causing organism, but does not show signs of disease?

A)Carrier
B)Transient
C)Resident
D)Indigenous

Question 11

The ability of an organism to produce disease in a susceptible individual is called:

A)pathogenicity.
B)iatrogenic infection.
C)parasitic infection.
D)opportunistic infection.

Question 12

Diabetics may sometimes be infected with their own resident flora.This type of infection is called:

A)an opportunistic infection.
B)a carrier state.
C)symbiosis.
D)a parasitic infection.

Question 13

What mechanism allows strict anaerobes to grow in the cervices and areas between the teeth when plaque is present?

A)A low oxidation-reduction potential occurs at the tooth surface under the plaque.
B)The bacteria secrete sugar to nourish the strict anaerobes.
C)The normal flora secrete antibiotics to kill all the other bacteria and allow the strict anaerobes to thrive.
D)The plaque-causing bacteria secrete an alkaline fluid and change the pH around the tooth.

Question 14

The stomach can be considered a first line of defense against microbial infections because:

A)most microorganisms are susceptible to the antibiotics and alkaline pH present in the stomach.
B)most microorganisms are killed by the liver enzymes that are emptied into the stomach during a meal.
C)the stomach produces proteases, which attacks the lipopolysaccharide cell wall of the organisms.
D)most microorganisms are susceptible to the acid pH of the stomach.

Question 15

Healthy people are colonized by many different bacteria in many different sites.These bacteria are referred to as _____ flora.

A)transient
B)carrier
C)maintenance
D)indigenous

Question 16

Mechanisms used by the skin to prevent infection and protect the underlying tissue from invasion by potential pathogens include all the following except:

A)desquamation of the epithelium.
B)excretion of lysozyme by sweat glands.
C)antibiotics that inhibit many microorganisms.
D)mechanical separation of microorganisms from the tissues.

Question 17

Factors that determine the pathogenicity and increase the virulence of organisms include all the following except an organism's ability to:

A)avoid phagocytosis.
B)produce exotoxins and extracellular enzymes.
C)produce infection when host conditions change.
D)survive intracellularly when phagocytized.

Question 18

During the childbearing years, the normal flora of the vagina maintain a low pH, thus encouraging colonization with all the following types of organisms except:

A)lactobacilli.
B)gram-negative rods.
C)anaerobic gram-negative bacilli.
D)gram-positive cocci.

Question 19

What is the name of a leukocidin that is lethal to leukocytes and produced by staphylococci?

A)Panton-Valentine
B)Lancefield
C)Hemolysin
D)Adhesins

Question 20

Parasitism is a:

A)biologic relationship between two or more organisms in which both benefit from one another.
B)biologic relationship between only two organisms in which there are no beneficial or harmful effects to the host.
C)biologic relationship in which one species gains benefits at the expense of the host.
D)synonym for mutualism.

Question 21

The effects of endotoxins consist of dramatic changes in all the following except:

A)blood pressure.
B)fluid imbalance.
C)clotting.
D)body temperature.

Question 22

A patient is brought to the emergency room with the following symptoms: body temperature of 102° F, low blood pressure, elevated WBC, and disseminated intravascular coagulation.This person has gram-negative rods growing in the blood.What is responsible for these symptoms?

A)Exotoxin
B)Extracellular enzymes
C)Endotoxin
D)Exfoliating toxin

Question 23

The process that results in enhanced phagocytosis by neutrophils is:

A)opsonization.
B)chemotaxis.
C)digestion.
D)glycolysis.

Question 24

What virus causes immune suppression in the host by targeting and destroying the host's CD4+ T cells?

A)HIV
B)Hepatitis B
C)Epstein-Barr
D)Cytomegalovirus

Question 25

After attachment to host cells, a pathogen may use the following mechanisms to establish itself and cause disease except:

A)uses lactoferrin for iron.
B)produces an IgA protease that degrades the IgA at mucosal surfaces.
C)produces lysozyme to kill the host cell.
D)circumvents host antibodies by shifting key cell-surface antigens.

Question 26

The major constituents of the adaptive or specific immune response are:

A)neutrophils.
B)macrophages.
C)monocytes.
D)lymphocytes.

Question 27

What are low-molecular-weight proteins secreted by T cells called?

A)Antibodies
B)Opsonins
C)Lymphokines
D)Lysozyme

Question 28

Innate immunity consists of which of the following components?

A)Physical and chemical barriers, such as the skin and mucous membranes
B)Blood proteins that act as mediators of infection
C)Cells capable of phagocytosis
D)All of the above are part of the innate immune system.

Question 29

Healthy skin secretes what substances to help prevent colonization by transient and possibly pathogenic organisms?

A)Long-chain fatty acids
B)Sebaceous glands
C)Carbohydrates
D)Antibodies

Question 30

Interferon is a substance produced by the body that inhibits viral replication.Interferon accomplishes this task by:

A)digesting the virus that is attempting to attach to the host cell.
B)destroying the host cell before the virus can attach and replicate.
C)binding to surface receptors that stimulate the cell to synthesize enzymes that inhibit viral replication over several days.
D)stimulating platelets to produce b-lysins.

Question 31

All the following activities must occur for phagocytosis to take place and be effective in host defense except:

A)attachment of the particle to the phagocyte.
B)ingestion.
C)killing.
D)migration of lymphocytes to the area of infection (chemotaxis).

Question 32

A physician notices that several patients are infected with Clostridium difficile, but only a few of the patients are symptomatic for disease.The reason for this discrepancy is:

A)only those strains of the organism carrying the extrachromosomal DNA coding for the toxin gene will produce toxin and cause the individuals to be symptomatic.
B)only those strains of the organism carrying DNA coding for the toxin within its main DNA molecule will produce toxin and cause the individuals to be symptomatic.
C)the exotoxin produced contains only the nontoxic portion.
D)the exotoxin must be produced in conjunction with extracellular enzymes to cause problems.

Question 33

Pathogens can be transmitted through all the following routes except:

A)ingestion.
B)handwashing.
C)sexual contact.
D)air.

Question 34

Immunity to intracellular bacterial pathogens, such as Mycobacterium tuberculosis, is primarily cell mediated, through the activities of:

A)interferons and macrophages.
B)antibodies and lymphokines.
C)lysozyme, T lymphocytes, and antibodies.
D)T lymphocytes, lymphokines, and macrophages.

Question 35

Lysozyme is a(n):

A)antibody produced by the skin.
B)low-molecular-weight enzyme that hydrolyzes the peptidoglycan layer of bacterial cell walls.
C)exotoxin that digests the lipopolysaccharide layer of the bacterial cell wall.
D)radical similar to hydrogen peroxide.

Question 36

Changes in what host structures can result in lower virulence of a microorganism?

A)Pili
B)Adhesin receptors
C)Surface polysaccharides
D)Phagocytes

Question 37

A subsequent exposure to the same antigen elicits a(n) _____ immune response characterized by a rapid increase in IgG antibody associated with higher levels, a prolonged elevation, and a more gradual decline in antibody levels.

A)primary
B)anamnestic
C)opsonin
D)innate

Question 38

Dissemination of a pathogen is when:

A)a pathogen penetrates and grows in tissues.
B)a pathogen multiplies intracellularly.
C)a pathogen circumvents host antibodies by shifting key cell-surface antigens.
D)infection with a pathogen spreads from the initial infection site to distant sites such as organs and tissues.

Question 39

Which class of antibodies is usually found as a pentamer?

A)IgM
B)IgG
C)IgA
D)IgE

Question 40

One of the most effective defenses bacteria have against phagocytosis is:

A)enzymes.
B)the capsule.
C)plasmids.
D)lipopolysaccharide layer.

Question 41

What is a form of food poisoning that can be life threatening even for otherwise healthy patients?

A)S.aureus
B)B.cereus
C)C.difficile
D)C.botulinum

Question 42

The classic example of a bite-wound infection is:

A)rabies.
B)S.aureus.
C)plague.
D)Ebola.

Question 43

The resulting disease from which route of transmission is a disease of animals that is transmitted to humans?

A)Sexual contact
B)Zoonotic
C)Airborne
D)Ingestion

Question 44

Because infections can be encountered via the air, _____ can cause transmission of some pathogens.

A)cuts
B)eyes
C)coughing
D)eating