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Microbiology > Exam #8: Zoonotic & Vector Borne Bacterial Infections I > Flashcards

Exam #8: Zoonotic & Vector Borne Bacterial Infections I Flashcards

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Biology 101 flashcards
1
Q

How is zoonosis prevented & controlled?

A

1) Avoidance of reservoirs and vectors
2) Eradicate reservoir or vector
3) Proper sanitation

*Note that vaccines are generally not feasible due to low incidence.

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2
Q

List the zoonotic bacteria that are considered bioterrorism agents.

A
  • Anthrax
  • Brucellosis
  • Meliodosis
  • Tularemia
  • Plague
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3
Q

List the characteristics of Anthrax.

A

Anthrax is caused by Bacillus anthracis

  • Gram positive rods
  • Aerobes
  • Spore-forming (remain viable for decades)– green spore
  • Appear in long chains with squared ends

“Boxcar” in culture

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4
Q

What virulence factors is associated with Anthrax?

A
  • Protein capsule, which is unique–others are polysaccharide
  • Protective antigen (like B) with either Lethal toxin or Edema toxin associated with it
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5
Q

What is the function of protective antigen?

A

Acts like B-subunit, binding

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6
Q

What is the mechanism of Lethal Toxin?

A

Disrupts normal cellular signaling events, leading to cell death, inflammation, and tissue damage

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7
Q

What is the mechanism of Edema Toxin?

A

Activates adenylate cyclase, increases cAMP, changes osmotic gradients, and ultimately leads to edema

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8
Q

Describe the pathenogenesis of Anthrax.

A
  • Spores are inoculated, ingested, or inhaled
  • Spores germinate into cells that produce toxin
  • Protective antigen binds cellular receptors on host tissues and cells
  • Protective antigen is then activated by host cell enzymes to form a multimeric complex on the host cell surface
  • LF or EF bind this complex & are internalized by the cell
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9
Q

What is Anthrax a primary disease of?

A

Herbivores: Cattle, sheep, goats, and horses

*This can be cultured on almost any farm; animals and soil are the principal reservoirs but there are only 1-2 cases anually

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10
Q

How is Anthrax prevented?

A

Vaccine in both animals and humans

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11
Q

What are the three types of Anthrax disease?

A

1) Inoculation
2) Inhalation
3) Ingestion

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12
Q

What is inoculation anthrax?

A

Direct inoculation of spores into open cuts or wounds

- Spores from soil, animal fur, hides, wool, or skin

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13
Q

What is inhalation anthrax?

A

Inhalation of spores

  • Bioterrorism
  • Previously called “wool-sorters disease”
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14
Q

What is ingestion anthrax?

A

Ingestion of spores

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15
Q

Describe the progression of Cutaneous anthrax.

A

1) Small red papule
2) Vesicle
3) Necrotic ulcer (eschar) is formed

*Described as painless & 5-20% are fatal without treatment

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16
Q

Describe the presentation of inhalation anthrax.

A

1) Initially presents as non-productive cough, dyspnea, myalgia, fatigue, and fever
2) Progresses to fever, drenching sweats, & severe dyspnea/cyanosis
3) By 3rd day, death in 100% without treatment

*Note that there is a long incubation period; pneumonia is rare; meningeal symptoms are in half of the cases

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17
Q

Describe the presentation of gastrointestinal anthrax.

A

1) Upper GI involvement includes oro-pharyngeal ulcerations with cervical lymphadenopathy & fever
2) Intestinal involvement includes abdominal pain, nasuea, fever, hematemesis, & hematochezia

*Note that the fatality rate with this disease is ~100%

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18
Q

How is gastrointestinal anthrax acquired?

A

Ingesting contaminated meat (likely with black eschar)

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19
Q

How is anthrax diagnosed?

A
  • Clinical signs
  • History
  • Microscopy
  • Culture

*Must inform lab that anthrax is suspected & handled under certain containment conditions

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20
Q

How is cutaneous (non-bioterrorism) anthrax treated?

A

Amoxacillin

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21
Q

How is inhalation, gastroinestinal, or bioterrorism anthrax treated?

A
  • Doxycycline or Ciprofloaxcin with 2x additional antibiotics
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22
Q

What is is causative organism of Brucellosis?

A

Brucella

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23
Q

List the characteristics of Brucella.

A
  • Gram negative coccobacilli
  • Intracellular pathogen

*Requires specialized media for culture

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24
Q

How is Brucella transmitted?

A

Aerosol or ingestion of

  • Contaminated food
  • Direct contact with infected animal
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25
Q

Describe the presentation of Brucellosis.

A
  • Acute undulating fever with joint pain, headache, & drenching sweat
  • This daily undulating fever is pathognomonic for Brucella/ Brucellosis

*Fever starts in the evening and is normally done by the morning

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26
Q

What does Brucella infection cause during pregnancy?

A

Spontaneous abortion
Premature delivery
Miscarriage

*Because of this, lab must be notified if this is what you suspect the patient may have

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27
Q

How is Brucellosis diagnosed?

A
  • Patient history
  • Lab MUST be notified
  • Blood culture
  • Serology
  • PCR
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28
Q

What is the treatment for Brucellosis?

A

6+ week course of Tetracycline (doxycycline) & rifampin

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29
Q

How is Brucellosis prevented?

A
  • Quaratine & vaccination of cattle, pasteuization of milk
  • Avoidance of imported unpasteurized soft cheeses/ home-made cheese
  • Better laboratory practices

*Note that Brucellosis is the #1 lab acquired infection

30
Q

What organism causes Pasteurellosis?

A

Pasteurella multocida

31
Q

List the characteristics of Pasteurella multocida.

A
  • Gram negative coccobacilli
  • Anaerobe
  • Commensals or normal flora in dogs & cats
  • Easy to culture
32
Q

What are the virulence factors associated with Pasteurella multocida?

A

LPS

HA capsule

33
Q

How is Pasteurellosis typically transmitted?

A
  • Infections commonly occur following the bite or scratch of a cat or dog
  • Also, letting dogs “lick” wounds
34
Q

Describe the presentation of Pasteurellosis.

A
  • Redness & swelling around the wound that becomes painful
  • Cellulitis and abscess formation
  • Lymphadenopathy
  • Possible spread to tendons, joints, and bones if untreated
35
Q

How is Pasteurellosis diagnosed?

A
  • Clinical signs
  • Hx of exposure
  • Culture and biochemical testing
36
Q

How is Pasteurellosis treated?

A

PCN

37
Q

What organism causes Leptospirosis?

A

Leptospira interrogans

38
Q

List the characteristics of Leptospira interrogans.

A
  • Thin, motile gram-negative spiral shaped bacterial with terminal hooks
  • Slow growth in culture
  • Poor staining
39
Q

Describe the pathogenesis of Leptospira interrogans.

A

1) Organism invades abraded skin or intact mucous membranes

2) Enters bloodstream & disseminates

40
Q

What is the clinical presentation of Leptospirosis?

A

Most infections present as self-limited, non-specific febrile illness

41
Q

Where is Leptospirosis most prevalent?

A
  • Most prevalent in the tropics
  • Cases in the US are seen mostly in Hawaii
  • Infection develops after exposure to contaminated animal urine or contaminated water
42
Q

What are the two phases of Leptospirosis?

A

1) febrile influenza-like illness
2) Disseminated phase if infection is not resolved
- Meningitis
- Eye infection
- Jaundice
- Renal failure
- Rash

43
Q

How is Leptospirosis diagnosed?

A
  • Hx
  • Culture is v. difficult
  • Serology is employed to confirm infection
44
Q

How is Leptospirosis treated?

A

PCN

Ampicillin

45
Q

How is Leptospirosis prevented?

A

Limiting exposure to animal urine

46
Q

What is the causative organism of Tularemia?

A

Francisella tularensis

47
Q

List the characteristics of Francisella tularensis.

A
  • Small, slow-growing, aerobic, Gram-negative coccobacilli
  • Difficult to grow in culture
  • Intracellular pathogens of monocytes & macrophages
48
Q

What virulence factors are associated with Francisella tularensis?

A

LPS
Polysaccharide capsule
Intracellular pathogen

*Prevents fusion of the phagosome-lysosome and acidification–>Cell-mediated activation is crucial for resoltuion of infection

49
Q

Where is Tularemia most commonly seen?

A

Primarily in the Northern Hemisphere (Oklahoma, Missouri, Arkansas)

  • Acquired by inhalation of infected blood aerosol when skinning animals
  • Ingestion of contaminated meat
50
Q

What are the reservoirs for Tularemia?

A

Wild mammals

51
Q

What is the vector for Tularemia?

A

Hard-shell ticks

52
Q

What is the difference between summer & fall/winter Tularemia?

A 
Summer= ticks 
Winter= small game
53
Q

What are the three types of Tularemia, and what are they dependent on?

A

There are three major forms of Tularemia that are dependent on the site of inoculation:

1) Skin= Ulceroglandular
2) Eye= Oculoglandular
3) Lungs= Pneumonic

54
Q

What are the symptoms of Ulceroglandular Tularemia?

A

This is caused by direct inoculation of Fraceisella tularemia into the skin

  • Red painful swollen papule that becomes swollen and ulcerates
  • Lymphadenopathy may occur with suppuration (filled with pus) & ultimately ulcerate
  • Patient may become bacteremic
  • Many patients will be febirle, experience headache, and photophobia
55
Q

What are the symptoms of Oculoglandular Tularemia?

A

This is caused by direct inoculation of Fraceisella tularemia into the eye
- Painful conjunctivitis with swollen cervical lymph nodes

56
Q

What are the symptoms of Pneumonic Tularemia?

A

This is caused by inhalation of Fraceisella tularemia

  • Causes pneumonitis & eventually sepsis
  • High rate of mortality and morbidity
57
Q

How is Tularemia diagnosed?

A
  • Hx
  • Serology and molecular techniques
  • Culture is slow and difficult

*Must inform lab of suspected case

58
Q

How is Tularemia treated?

A

Gentamicin

59
Q

How is Tularemia prevented?

A
  • Prevent tick bites

- Hunter education i.e. precautions when skinning animals

60
Q

What is the causative organism of the Plague?

A

Yersinia pestis

61
Q

List the characteristics of Yersinia pestis.

A
  • Gram negative rod
  • Non-motile
  • Produces a PROTEIN capsule
62
Q

What is the difference between the appearance of Yersinia Pestis on Giemsa stain & Gram stain?

A

Gram= red (negative)

Geimsa= purple with “closed safety pin” morphology

63
Q

What are the virulence factors associated with Yersinia pestis?

A
  • Protein capsule
  • LPS

3x plasmids associated with virulence

  • Biofilm formation
  • Enhanced resistance to macrophage killing
  • Complement resistance
64
Q

What animals serve as reservoirs for Yersinia pestis?

A
  • Mostly rodents

- Rat fleas

65
Q

What is the most important animal reservoir of Yersinia pestis in the US?

A

Prarie dogs

66
Q

How is Yersinia pestis transmitted?

A
  • Bite from infected fleas
  • Bites & scratches from cats that killed infected rodents
  • Inhalation of aerosol

Human–>human is possible

67
Q

What are the symptoms of Bubonic plague.

A

Bubonic plague is caused by a flea bite

  • Fever, chills, headache, myalgia
  • Painful lymphadenopathy develops proximal to the port of entry– called “buboes”
  • Surrounding area becomes swollen and inflammed
  • Overlying skin may be stretched & desquamate
  • Buboes may perforate if untreated–>bacteremia & septic shock
  • Gangrene of the extremities

50% mortality

68
Q

What is pneumonic plague?

A

Inhalation of respiratory droplets from an infected person or animal (Yersinia pestis)

69
Q

What are the symptoms of Pneumonic plague?

A
  • Fever, headache, myalgias & respiratory signs
  • Progresses rapidly to symptoms of hemoptysis, resp. distress, cardiopulmonary insufficiency, cyanosis, and circulatory collapse

100% mortality

70
Q

How is plague diagnosed?

A

History

71
Q

How is plague treated?

A

Streptomycin

Microbiology (49 decks)

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