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Exam 18: Microbial Pathogenesis

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Question 1

Multiple Choice

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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.

E) C) and D)
F) A) and D)

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Question 2

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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.

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It is a facultative intracellular pathogen.Surviving environmentally allows the organism to be transmitted through foods like unpasteurized cheeses.It is also known to survive intracellularly,escaping the phagosome and utilizing intracellular transport mechanisms to cross the placental barrier.

Question 3

Short Answer

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

Which statement about horizontal gene transfer is correct?

Which of the following statements is FALSE?

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

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

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

Alpha toxin secreted by Staphylococcus aureus is a

Damage from protozoan infections is due mainly to the

Endotoxins are

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

All of the following are targets for bacterial toxins EXCEPT

All of the following are methods of microbial attachment EXCEPT

Most pathogenicity island genes were acquired by ________ transmission.

All of the following statements are true about HIV EXCEPT

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?

Genomic islands have all of the following features EXCEPT

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

Which of the following is true regarding the herpes virus?