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Micro Winter Exam 2 > L16: Typhoid Fever And Plague > Flashcards

L16: Typhoid Fever And Plague Flashcards

1
Q

What are the virulence factors associated with Salmonella Typhi?

A

Pathogenicity Island SPI1 T3SS, SPI2 T3SS, Typhoid toxin

SPI1 is required for invasion of intestinal epithelial cells, SPI2 is required for survival in the phagosome of macrophages.

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2
Q

What are the main signs and symptoms of Typhoid Fever?

A

Fever, headache, malaise, enlarged liver and spleen, rose spot rash

The rash is only seen in about 30% of cases.

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3
Q

How is Typhoid Fever transmitted?

A

Ingestion of contaminated food or water, close contact with a carrier

Asymptomatic carriers can transmit the disease.

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4
Q

What is the incubation period for Typhoid Fever?

A

10 to 14 days

Higher infectious doses lead to shorter incubation periods.

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5
Q

What are the common symptoms of non-typhoid Salmonella gastroenteritis?

A

Nausea, vomiting, diarrhea

Symptoms appear 6 to 48 hours post ingestion and typically resolve in about 5 days.

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6
Q

Which Salmonella serovars are responsible for Typhoid Fever?

A

Salmonella enterica serovars Typhi, Paratyphi A, Paratyphi B

Paratyphi A and B cause Paratyphoid fever, which is not distinguishable from Typhoid fever.

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7
Q

What is the mechanism of action of Typhoid toxin?

A

Inhibition of G protein coupling with GPCR, blocking cell signaling

Similar activity to pertussis toxin.

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8
Q

What are the treatment options for Typhoid Fever?

A

Ceftriaxone for 14 days, fluoroquinolones for 7 to 10 days

Antibiotic resistance is common, and susceptibility testing should be performed.

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9
Q

What is the estimated annual incidence of Typhoid Fever worldwide?

A

11 to 21 million new cases

Up to 161,000 deaths annually.

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10
Q

What is the primary cause of bubonic plague?

A

Yersinia pestis

The organism is spread by fleas that feed on infected rodents.

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11
Q

What is the incubation period for bubonic plague?

A

2 to 7 days

The organism replicates in macrophages and spreads to lymph nodes.

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12
Q

What are the symptoms of bubonic plague?

A

Swollen lymph nodes (buboes), sudden fever, headache, bacteremia

75% of untreated patients may die.

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13
Q

What is the role of fleas in the transmission of Yersinia pestis?

A

Fleas regurgitate blood containing Yersinia pestis into hosts during feeding

This leads to bloodborne infections resulting in bubonic plague.

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14
Q

What type of vaccine is available for Typhoid Fever?

A

Live, attenuated oral vaccine (Ty21a) and inactivated polysaccharide capsule-based vaccine (ViCPS)

Ty21a requires four doses, while ViCPS is a single injection.

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15
Q

True or False: Typhoid toxin shows selectivity for Neu5Gc-terminal glycans.

A

False

Typhoid toxin shows strong selectivity for Neu5Ac-terminal glycans found in human cells.

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16
Q

What is the percentage of untreated Typhoid Fever cases that lead to carrier status?

A

About 3%

Carrier status is more common in women.

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17
Q

Fill in the blank: The first pandemic of plague is known as the _______.

A

Justinian Plague

It killed approximately 50% of the population of Europe.

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18
Q

What is the common laboratory diagnosis for Typhoid Fever?

A

Culture of S. Typhi from blood or sterile body fluid

Bone marrow aspirate is more sensitive but used after multiple failed blood cultures.

19
Q

What is the incubation period for Yersinia pestis infection?

A

2 to 7 days

20
Q

In which type of cells does Yersinia pestis replicate?

A

Macrophages

21
Q

What are the symptoms of Yersinia pestis infection?

A

Sudden fever, headache

22
Q

What percentage of untreated patients with Yersinia pestis die?

A

75%

23
Q

What form of plague usually stems from bubonic infection?

A

Pneumonic plague

24
Q

True or False: Pneumonic plague can spread from person to person.

A

True

25
Q

What is the mortality rate for untreated pneumonic plague?

A

Almost 100%

26
Q

What is the key virulence factor of Yersinia pestis that degrades fibrin clots?

A

Pla – plasminogen activator

27
Q

What does the Ail protein do in Yersinia pestis?

A

Required for attachment and invasion of epithelial cells

28
Q

Fill in the blank: Yersinia pestis is a __________ Agent according to the CDC.

A

Category A Bioterrorism

29
Q

What are the primary treatment options for Yersinia pestis?

A
  • Streptomycin
  • Gentamicin
  • Doxycycline
  • Ciprofloxacin
  • Levofloxacin
  • Moxifloxacin
  • Chloramphenicol
30
Q

What is the recommended timeframe for starting treatment for septicemic or pneumonic plague?

A

Within 24 hours

31
Q

What should be done for suspected cases of Yersinia pestis?

A

Isolated and treated

32
Q

What personal protective equipment (PPE) should be worn by healthcare providers for suspected plague cases?

A
  • Gloves
  • Gowns
  • Eye protection
  • N95 or N100 particulate respirator
33
Q

What is the average number of plague cases per year in the US?

A

7 cases

34
Q

What percentage of plague cases in the US since 1900 have been bubonic?

A

80%

35
Q

What is the role of Yersinia outer proteins (Yops) during the infection process?

A

Prevent uptake and lead to macrophage apoptosis

36
Q

What does the Type 3 Secretion System (T3SS) do in Yersinia pestis?

A

Injects Yops into macrophages to dampen immune response

37
Q

What does elevated leukocyte count with low platelet count indicate in Yersinia pestis diagnosis?

A

Potential for DIC

38
Q

What type of agar is used to culture Yersinia pestis?

A

Brain-Heart infusion broth, blood agar, and MacConkey agar

39
Q

Fill in the blank: Vaccines for Y. pestis are no longer available in the __________ or __________.

A

United States, Europe

40
Q

What should be done for all pneumonic plague contacts?

A

Under medical surveillance with temperatures taken every 4 hours for 6 days

41
Q

What antibiotic should be given for oral prophylaxis in close contacts of plague patients?

A
  • Doxycycline 100 mg every 12 hours
  • Ciprofloxacin 500 mg every 12 hours
42
Q

What happens to the immune response when Yersinia pestis induces uptake by macrophages?

A

Dampening of immune response

43
Q

True or False: Prior vaccination excludes the possibility of plague in vaccinated individuals.

A

False

44
Q

What are the potential terminal conditions of Yersinia pestis infection?

A

Meningitis and pneumonia

Micro Winter Exam 2 (12 decks)

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