Deck 15: Microbial Mechanisms of Pathogenicity

Question 1

Which of the following organisms doesn't produce an exotoxin?

A) Clostridium botulinum
B) Corynebacterium diphtheriae
C) Staphylococcus aureus
D) Salmonella typhi
E) Clostridium tetani

Answer 1

D

Question 2

A cell wall can increase a bacterium's virulence because cell wall lipid A

A) Helps the bacterium attach.
B) Destroys host tissues.
C) Resists phagocytosis.
D) All bacteria have a cell wall and all are not pathogenic; therefore, cell walls do not contribute to virulence.
E) None of the above.

Answer 2

E

Question 3

Which of the following does not contribute to the symptoms of a fungal disease?

A) Capsules
B) Toxins
C) Cell walls
D) Allergic response of the host
E) None of the above

Answer 3

C

Question 4

Poliovirus is ingested and gains access to tissues by which portal of entry?

A) Parenteral
B) Skin
C) Mucous membranes
D) All of the above
E) None of the above

Question 5

The mechanism by which gram- negative bacteria can cross the blood- brain barrier.

A) Producing toxins
B) Producing fimbriae
C) Inducing endocytosis
D) Inducing TNF
E) All of the above

Question 6

In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes

A) A fever.
B) A decrease in blood pressure.
C) The disease to subside.
D) A gram- negative infection.
E) None of the above.

Question 7

Which of the following is not true of staphylococcal enterotoxin?

A) It is an exotoxin.
B) It causes vomiting.
C) It is produced by Staphylococcus aureus growing in the host's intestines.
D) It causes diarrhea.
E) None of the above.

Question 8

Septic shock due to gram- positive bacteria is caused by

A) Superantigens.
B) Membrane- disrupting toxins.
C) Lipid A.
D) A- B toxins.
E) All of the above.

Question 9

Symptoms of protozoan and helminthic diseases are due to

A) Tissue damage due to growth of the parasite on the tissues.
B) Products released from damaged tissues.
C) Waste products excreted by the parasite.
D) All of the above.
E) None of the above.

Question 10

Which is a method of avoiding phagocytosis?

A) Inducing TNF
B) Producing fimbriae
C) Inducing endocytosis
D) Producing toxins
E) All of the above

Question 11

A needlestick is an example of which portal of entry?

A) Mucous membranes
B) Skin
C) Parenteral route
D) All of the above
E) None of the above

Question 12

Siderophores are bacterial proteins that compete with animal

A) Red blood cells.
B) Transferrin.
C) White blood cells.
D) Antibodies.
E) None of the above.

Question 13

Lysogenic bacteriophages contribute to bacterial virulence because bacteriophages

A) Give new gene sequences to the host bacteria.
B) Kill the bacteria causing release of endotoxins.
C) Carry plasmids.
D) Produce toxins.
E) All of the above.

Question 14

The symptoms of tetanus are due to

A) Encapsulated Clostridium tetani.
B) An exotoxin produced by Clostridium tetani.
C) The growth of Clostridium tetani in a wound.
D) Hemolysins produced by Clostridium tetani.
E) All of the above.

Question 15

Antibiotics can lead to septic shock if used to treat

A) Gram- negative bacterial infections.
B) Viral infections.
C) Helminth infestations.
D) Protozoan infections.
E) Gram- positive bacterial infections.

Question 16

Which of the following is not used for attachment to a host?

A) Ligands
B) M protein
C) Fimbriae
D) Capsules
E) None of the above.

Question 17

Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed

A) Polypeptide B would not be able to enter the cells.
B) Polypeptide A would enter the cells.
C) Polypeptide A would bind to target cells.
D) Vibrio would not produce cholera toxin.
E) None of the above.

Question 18

Table 15.1
Use these data to answer the following question:
$\begin{array}{lll} \underline{\text { Bacteria}} & \underline{\text { Portal of entry }} & \underline{\mathrm{ID} 50} \\ \text { Staphylococcus aureus } & \text { Wound } & <10 \\ \text { S. aureus } & \text { Wound }+ \text { ampicillin } & 300\end{array}$

-The administration of ampicillin before surgery

A) Replaces tetracycline.
B) Increases the risk of staphylococcal infection.
C) Decreases the risk of staphylococcal infection.
D) Has no effect on risk of infection.
E) Can't tell.

Question 19

Which of the following is not a membrane- disrupting toxin?

A) Streptolysin O
B) Leucocidin
C) Hemolysin
D) A- B toxin
E) Streptolysin S

Question 20

Which of the following is not a cytopathic effect of viruses?

A) Inclusion bodies form in the cytoplasm or nucleus
B) Cell death
C) Increased cell growth
D) Host cells fuse to form multinucleated syncytia
E) None of the above

Question 21

Which of the following does not contribute to the virulence of a pathogen?

A) Numbers of microorganisms that gain access to a host
B) Toxins
C) Cell wall
D) Enzymes
E) None of the above

Question 22

Injectable drugs are tested for endotoxins by

A) Filtering out the cells.
B) Looking for turbidity.
C) The Limulus amoebocyte lysate test.
D) Counting the viable bacteria.
E) None of the above.

Question 23

All of the following may be used for adherence except

A) Cell membrane mannose.
B) Lipoproteins.
C) Glycoproteins.
D) Capsules.
E) Fimbriae.

Question 24

The most frequently used portal of entry for pathogens is the

A) Parenteral route.
B) Mucous membranes of the respiratory tract.
C) Mucous membranes of the gastrointestinal tract.
D) Skin.
E) All are used equally.

Question 25

Endotoxins are

A) Excreted from the cell.
B) Specific in their method of action.
C) Part of the gram- negative cell wall.
D) Associated with gram- positive bacteria.
E) None of the above.

Question 26

Gram- negative septic shock results from the following events. What is the second step?

A) Fever occurs.
B) Phagocytes ingest gram- negative bacteria.
C) LPS is released from gram- negative bacteria.
D) Body temperature is reset in the hypothalamus.
E) IL- 1 is released.

Question 27

Pseudomonas aeruginosa produces a two- part exotoxin. The most likely pathologic effect of this toxin is

A) A red rash.
B) Tetani or lockjaw.
C) Flaccid paralysis.
D) The bacteria will be able to grow in phagocytes.
E) Inhibition of protein synthesis.

Question 28

Which of the following diseases is not usually contracted by the respiratory route?

A) Tuberculosis
B) Infectious hepatitis
C) Pneumonia
D) Measles
E) None of the above

Question 29

Cytopathic effects are changes in host cells due to

A) Protozoan and helminthic infections.
B) Viral infections.
C) Bacterial infections.
D) Fungal infections.
E) All of the above.

Question 30

Which of the following is not considered entry via the parenteral route?

A) Hair follicle
B) Injection
C) Surgery
D) Bite
E) None of the above

Question 31

Botulism is caused by an exotoxin, therefore it could easily be prevented by

A) Not eating canned food.
B) Preventing fecal contamination of food.
C) Boiling food prior to consumption.
D) Administering antibiotics to patients.
E) None of the above.

Question 32

Which of the following cytopathic effects is cytocidal?

A) Transformation
B) Antigenic changes
C) Giant cells
D) Release of enzymes from lysosomes
E) Inclusion bodies

Question 33

All of the following are methods of avoiding host antibodies except

A) Invasims.
B) Membrane- disrupting toxins.
C) Antigenic change.
D) IgA protease.
E) None of the above

Question 34

Which of the following does not contribute to a pathogen's invasiveness?

A) Toxins
B) Hyaluronidase
C) Ligands
D) Cell wall
E) Capsule

Question 35

Which of the following statements is false?

A) Kinase destroys fibrin clots.
B) Coagulase destroys blood clots.
C) Hemolysins lyse red blood cells.
D) Leukocidins destroy neutrophils.
E) Hyaluronidase breaks down substances between cells.

Question 36

Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that

A) Bacteria that cause periodontal disease adhere to teeth.
B) Streptococci cause periodontal disease.
C) Streptococci get bacterial infections.
D) Streptococcal colonization is necessary for periodontal disease.
E) Bacteria that cause periodontal disease adhere to gums and teeth.

Question 37

Which of the following statements about exotoxins is generally not true?

A) They are produced by gram- positive bacteria.
B) They are composed of proteins.
C) They are not destroyed by heat.
D) They have specific methods of action.
E) They are more potent than endotoxins.

Question 38

The ID50 is a

A) Dose that will kill some of the test population.
B) Dose that will kill 50% of the test population.
C) Measure of pathogenicity.
D) Dose that will cause an infection in some of the test population.
E) Dose that will cause an infection in 50% of the test population.

Question 39

All of the following are true about M protein except

A) It is a protein.
B) It is found on fimbriae.
C) It is heat- and acid- resistant.
D) It is readily digested by phagocytes.
E) It is found on Streptococcus pyogenes.

Question 40

Thirty- two people in San Francisco who ate jackfish caught at Midway Island developed malaise, nausea, blurred vision, breathing difficulty, and numbness from 3 to 6 hours after eating. The most likely cause of this food intoxication is

A) Aflatoxin.
B) Cholera toxin.
C) Staphylococcal enterotoxin.
D) Ciguatera.
E) A mycotoxin.

Question 41

Most pathogens that gain access through the skin

A) Must adhere first while their invasive factors allow them to penetrate.
B) Must be injected.
C) Can penetrate intact skin.
D) Enter through hair follicles and sweat ducts.
E) Just infect the skin itself.

Question 42

Endotoxins in injectable drugs could cause

A) Nerve damage.
B) Giant cell formation.
C) Septic shock.
D) Infection.
E) All of the above.

Question 43

Nonpathogenic V. cholerae can acquire the cholera toxin gene by

A) Conjugation.
B) Transformation.
C) Phagocytosis.
D) Transduction.
E) None of the above.