Deck 18: Microbial Pathogenesis

Question 1

All of the following are methods of microbial attachment EXCEPT

A) capsids.
B) pili.
C) fimbriae.
D) type IV secretion systems.

Answer 1

D

Question 2

The fimbriae of E.coli is an example of a(n)

A) adhesion.
B) receptor.
C) endotoxin.
D) exotoxin.

Answer 2

A

Question 3

All of the following are ways bacteria evade phagocytic digestion and survive intracellularly EXCEPT

A) escaping the phagosome.
B) toxin production within the phagosome.
C) inhibiting lysosome-phagosome fusion.
D) survival within the phagolysosome.

Answer 3

B

Question 4

Genomic islands have all of the following features EXCEPT

A) they are flanked by phage or plasmid genes.
B) the ratio of GC/AT nucleases.
C) they do not need toxins or secretion systems.
D) they encode clusters of genes that contribute to the fitness of the organism.

Question 5

Which of the following statements is FALSE?

A) Hemolysins lyse red blood cells.
B) Leukocidins destroy neutrophils.
C) AB toxins interfere with protein synthesis.
D) Protease exotoxins build proteins.

Question 6

Rickettsia will not grow outside a living eukaryotic cell.What type of organism is this?

A) extracellular pathogen
B) facultative intracellular pathogen
C) intracellular pathogen
D) obligate extracellular pathogen

Question 7

All of the following are targets for bacterial toxins EXCEPT

A) signal transduction.
B) host membranes.
C) DNA synthesis.
D) protein synthesis.

Question 8

Interfering with microbial attachment results in

A) making a pathogenic organism nonvirulent.
B) disrupting toxin production.
C) increased formation of microbial biofilms.
D) increased virulence.

Question 9

Alpha toxin secreted by Staphylococcus aureus is a

A) hyaluronidase.
B) leucocidin.
C) kinase.
D) hemolysin.

Question 10

Type I pili are different from type IV pili in that type I pili

A) are static structures.
B) are thin and flexible.
C) allow for twitching motility.
D) are dynamic.

Question 11

Which statement about horizontal gene transfer is correct?

A) Few pathogenicity islands are generated by horizontal transmission.
B) Horizontal gene transfers move whole blocks of DNA from one organism to another.
C) Horizontal gene transfer helps pathogens evolve.
D) All genes code for toxins.

Question 12

Biofilm infections are important clinically because

A) WBC easily penetrate biofilms.
B) bacteria in biofilms are more susceptible to antimicrobial compounds.
C) bacteria in biofilms can persist against host defenses.
D) bacteria in biofilms do not grown on medical devices.

Question 13

Which of the following is NOT an example of a bacterial secretion system that is paralogous to another molecular machine?

A) type 1 protein secretion system
B) type II protein secretion system
C) type III protein secretion system
D) type IV protein secretion system

Question 14

All of the following are exotoxins EXCEPT

A) superantigens.
B) AB toxins.
C) plasma membrane disruption toxins.
D) lipopolysaccharide.

Question 15

All of the following statements about type III secretion systems are true EXCEPT

A) proteins are injected directly into the eukaryotic cells.
B) type III secretion systems are evolutionarily related to flagellar genes.
C) cell-to-cell contact triggers type III secretion systems.
D) virulence proteins secreted by type III systems alter protein synthesis.

Question 16

Shiga toxin polypeptide B binds to surface gangliosides on target cells.If the gangliosides were removed

A) polypeptide A would bind to target cells.
B) polypeptide A would enter the cells.
C) polypeptide B would not be able to bind.
D) Vibrio would not produce cholera toxin.

Question 17

Which of the following is true regarding type II secretion systems?

A) The type II secretion genes are homologous to the type IV pilus.
B) Type II secretion mechanisms are static with no twitching motility.
C) Proteins secreted by type II secretion systems are secreted directly out of the cell.
D) Shiga toxin is a well-known example of a protein that a type II secretion mechanism expels.

Question 18

All of the following are true about cholera toxin EXCEPT that it

A) is an endotoxin.
B) is an AB toxin.
C) reverses the absorption process in the intestines.
D) causes severe diarrhea.

Question 19

Refer to the figure below.The secretion system displayed mirrors that of a pilus.Which secretion system is this?

A) type I
B) type II
C) type III
D) type IV

Question 20

Endotoxins are

A) associated with Gram-positive bacteria.
B) molecules that bind nerve cells.
C) part of the Gram-negative cell wall.
D) excreted from the cell.

Question 21

Damage from protozoan infections is due mainly to the

A) toxins that are released.
B) ability of the organism to persist within host tissue.
C) ability of the organism to turn on the host immune system.
D) cell wall components of the pathogen.

Question 22

Which of the following protozoans uses antigenic variation to circumvent the host immune system?

A) plasmodium
B) entamoeba
C) leishmania
D) trypanosome

Question 23

CASE HISTORY
Will,a formerly rambunctious five-year-old from San Francisco,was taken to the emergency department after having a severe cough for two weeks.His illness started as a runny nose,dry cough,and low-grade fever.But within days the coughing would come in violent fits lasting up to one minute (called a paroxysm).The nurse practitioner attending Will observed one of these fits.Unable to breathe between coughs,the boy became cyanotic (turned blue).When the staccato of coughs finally ended,Will gasped,desperate for breath.The air rushing to fill his lungs made an ear-piercing whooping sound.This telltale "whoop" led the nurse practitioner to suspect whooping cough,a disease highly contagious in its early stages.In the later stages (greater than four weeks)the patient is no longer contagious because the bacterial agent,Bordetella pertussis,has succumbed to the immune response.However,the telltale cough will persist for weeks while the lungs repair the damage caused by the pertussis toxins.The nurse practitioner,now wearing a mask,took a nasopharyngeal swab sample for bacteriological culture and prescribed the antibiotic azithromycin (a member of the macrolide class of antibiotics that inhibit protein synthesis).Because the organism takes so long to grow in the laboratory (5-12 days)and because the organism is hard to find late in the disease,a blood sample was also drawn to test for anti-B.pertussis immunoglobulin a antibody.By the next day the serum test was positive for B.pertussis antibodies.The pathogen eventually also grew in the culture.Despite extensive efforts at vaccination,more than 41,000 cases of whooping cough were reported in the United States in 2012.
Several of the protein exotoxins produced by Bordetella pertussis act by disrupting signal transduction.Which of the following exotoxin-target pairs is NOT properly matched?

A) Cholera toxin-disrupts signal transduction (increase cAMP synthesis much like in pertussis)
B) Anthrax toxin-forms pores in membranes, allowing bacteria to escape vacuoles
C) Shiga toxin-inhibits protein synthesis, leading to hemolytic uremic syndrome
D) Staphylococcal alpha toxin-forms pores in membranes, leading to lysis of blood cells

Question 24

What is the purpose of the actin-myosin motor shown in the figure below?

A) The pathogen uses this structure to enter the host cell.
B) The pathogen uses this structure to produce toxins.
C) The pathogen uses this structure as a secretion apparatus.
D) The pathogen uses this structure to prevent phagocytosis.

Question 25

All of the following are required for disease to occur.What is the second step in microbial pathogenesis?

A) pathogen exit
B) host damage
C) pathogen entry
D) tissue attachment

Question 26

The purpose of the Tat protein in an HIV infection is to

A) down regulate CD4 and MHC class 1 expression.
B) inhibit virus assembly.
C) accelerate HIV transcription by the host cell.
D) protect the cell from being killed by CD8 cytotoxic cells.

Question 27

Protozoans use all the following mechanisms to avoid the host immune system EXCEPT

A) antigenic variation.
B) toxin production.
C) antigenic masking.
D) intracellular location.

Question 28

All of the following statements are true about HIV EXCEPT

A) HIV produces a Nef protein, which prevents T-cell apoptosis.
B) Tat increases MHC 1 synthesis on host cells.
C) Nef protein inhibits a regulatory cascade that leads to apoptosis.
D) Tat stimulates apoptosis in infected host cells.

Question 29

Organisms such as Shigella and Listeria are able to move from cell to cell without being detected by the host immune system.What method are they using?

A) production of an actin tail that propels them from cell to cell
B) production of a capsule to avoid antibody binding
C) production of protein A molecules to bind the Fc region of antibodies
D) production of proteins to trigger apoptosis in host cells

Question 30

Which of the following is true regarding the herpes virus?

A) It is the etiological agent of cervical warts.
B) The virus cannot enter into a latent state in neural ganglia.
C) Latent herpes virus DNA produces microRNAs that interfere with apoptosis.
D) Herpes viruses are double-stranded RNA viruses.

Question 31

According to the figure below,which of the following is true about Coxiella?

A) Coxiella prevents the lysosome from fusing with the phagosome.
B) Coxiella prevents phagosome-lysosome fusion.
C) Once inside the phagosome, Coxiella interferes with cell-signaling pathways.
D) It escapes the phagosome before lysosomal fusion.

Question 32

Antigenic drift occurs when

A) two viruses infect the same cell.
B) a new viral strain is produced.
C) random mutations occur in the neuraminidase spike.
D) random mutations occur in the hemagglutinin spike.

Question 33

Which of the following is an example of an obligate intracellular pathogen?

A) Listeria monocytogenes
B) Shigella dysenteriae
C) Coxiella burnetii
D) Streptococcus pneumoniae

Question 34

In viruses such as influenza,the ability to undergo a major genetic alteration is called

A) antigenic drift.
B) antigenic shift.
C) antigenic variation.
D) antigenic binding.

Question 35

Once a bacterium attaches and enters a host cell within a phagosome,the pathogen has one of three fates,depending on the pathogen.According to the figure below,Shigella and Listeria utilize which mechanism to avoid being destroyed by the host cell?

A) survive inside the phagosome
B) escape from the phagosome
C) prevent phagosome-lysosome fusion
D) induce apoptosis

Question 36

All of the following are ways pathogens avoid destruction by the host immune system EXCEPT

A) capsules.
B) triggering apoptosis.
C) antigenic variations.
D) toxin production.

Question 37

Cervical warts are caused by

A) HBV.
B) HPV.
C) HIV.
D) herpes.

Question 38

The human immunodeficiency virus (HIV)primarily targets which subset of immune cells?

A) CD8+ T cells
B) CD4+ T cells
C) macrophages
D) dendritic cells

Question 39

All of the following are true about bacterial capsules EXCEPT

A) they are produced by intracellular pathogens to avoid the host immune system.
B) they coat bacterial cell wall components inhibiting phagocytosis.
C) the slippery nature of capsules make "grabbing" the bacterial cell difficult.
D) the immune system attacks encapsulated organisms with opsonizing antibodies.

Question 40

The structure labeled as "A" in the figure below is called a(n)

A) protease.
B) MIC protein.
C) nucleus.
D) actin-myosin motor.

Question 41

Some microbes use tiny molecular syringes called ________ to inject proteins directly into the host cytoplasm.

Question 42

CASE HISTORY
Shakia was in her fourth month of pregnancy and excited to become a mother.A 33-year-old African American from Indianapolis,Shakia had been in good health until about a week ago,when she started to experience abdominal pain,fever,muscle aches,and diarrhea.She visited her obstetrician to make sure it was nothing serious.When the obstetrician asked whether she had eaten anything unusual in the past few weeks,Shakia recalled eating some soft Mexican cheese about three weeks earlier during a visit to Oregon with her husband.The physician sent a sample of Shakia's blood and stool to the local diagnostic laboratory and prescribed the antibiotic ampicillin as treatment.The lab reported finding a Gram-positive,non-spore-forming bacillus called Listeria monocytogenes in both the fecal and blood samples.Shakia had mild gastroenteritis and septicemia.The septicemia placed her unborn child at serious risk of infection because this bacterium can cross the placental barrier.If not treated quickly,an infected fetus has a 70% chance of dying from meningitis and multiple organ system failure.The doctor hoped she treated Shakia in time.
Is Listeria monocytogenes an extracellular,facultative intracellular,or obligate intracellular pathogen? Describe the features of infection that support your conclusion.

Question 43

Most pathogenicity island genes were acquired by ________ transmission.

Question 44

CASE HISTORY
Will,a formerly rambunctious five-year-old from San Francisco,was taken to the emergency department after having a severe cough for two weeks.His illness started as a runny nose,dry cough,and low-grade fever.But within days the coughing would come in violent fits lasting up to one minute (called a paroxysm).The nurse practitioner attending Will observed one of these fits.Unable to breathe between coughs,the boy became cyanotic (turned blue).When the staccato of coughs finally ended,Will gasped,desperate for breath.The air rushing to fill his lungs made an ear-piercing whooping sound.This telltale "whoop" led the nurse practitioner to suspect whooping cough,a disease highly contagious in its early stages.In the later stages (greater than four weeks)the patient is no longer contagious because the bacterial agent,Bordetella pertussis,has succumbed to the immune response.However,the telltale cough will persist for weeks while the lungs repair the damage caused by the pertussis toxins.The nurse practitioner,now wearing a mask,took a nasopharyngeal swab sample for bacteriological culture and prescribed the antibiotic azithromycin (a member of the macrolide class of antibiotics that inhibit protein synthesis).Because the organism takes so long to grow in the laboratory (5-12 days)and because the organism is hard to find late in the disease,a blood sample was also drawn to test for anti-B.pertussis immunoglobulin a antibody.By the next day the serum test was positive for B.pertussis antibodies.The pathogen eventually also grew in the culture.Despite extensive efforts at vaccination,more than 41,000 cases of whooping cough were reported in the United States in 2012.
As a Gram-negative bacterium,Bordetella pertussis produces endotoxin.Why is this toxin not a major contributor to the disease signs and symptoms associated with pertussis?

Question 45

Organisms that can survive inside or outside host cells are called ________ pathogens.

Question 46

Draw and label an AB toxin.List two diseases that are caused by AB toxins.

Question 47

Explain the difference between antigenic drift and antigenic shift.How might antigenic shift relate to the generation of a new flu pandemic?

Question 48

Using the figure below,explain how Salmonella enterica uses its type III secretion systems to invade the eukaryotic host cell and become an intracellular parasite.

Question 49

Organized,high-density communities of cells that embed themselves in self-made exopolymer matrices are called ________.

Question 50

Toxins made and secreted by bacterial cells are called ________ while toxins contained within the bacterial cell wall are called ________.

Question 51

The figure below illustrates T.brucei inside a host.Explain what is happening in the figure.

Question 52

Label the figure below with where the Tetanus,Shiga,and Cholera toxins affect cellular function.