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

Exam #8: Zoonotic & Vector Borne Bacterial Infections I 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
Describe the presentation of Brucellosis.
- 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
26
What does Brucella infection cause during pregnancy?
Spontaneous abortion Premature delivery Miscarriage *Because of this, lab must be notified if this is what you suspect the patient may have
27
How is Brucellosis diagnosed?
- Patient history - Lab MUST be notified - Blood culture - Serology - PCR
28
What is the treatment for Brucellosis?
6+ week course of Tetracycline (doxycycline) & rifampin
29
How is Brucellosis prevented?
- 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
What organism causes Pasteurellosis?
Pasteurella multocida
31
List the characteristics of Pasteurella multocida.
- Gram negative coccobacilli - Anaerobe - Commensals or normal flora in dogs & cats - Easy to culture
32
What are the virulence factors associated with Pasteurella multocida?
LPS | HA capsule
33
How is Pasteurellosis typically transmitted?
- Infections commonly occur following the bite or scratch of a cat or dog - Also, letting dogs "lick" wounds
34
Describe the presentation of Pasteurellosis.
- Redness & swelling around the wound that becomes painful - Cellulitis and abscess formation - Lymphadenopathy - Possible spread to tendons, joints, and bones if untreated
35
How is Pasteurellosis diagnosed?
- Clinical signs - Hx of exposure - Culture and biochemical testing
36
How is Pasteurellosis treated?
PCN
37
What organism causes Leptospirosis?
Leptospira interrogans
38
List the characteristics of Leptospira interrogans.
- Thin, motile gram-negative spiral shaped bacterial with terminal hooks - Slow growth in culture - Poor staining
39
Describe the pathogenesis of Leptospira interrogans.
1) Organism invades abraded skin or intact mucous membranes | 2) Enters bloodstream & disseminates
40
What is the clinical presentation of Leptospirosis?
Most infections present as self-limited, non-specific febrile illness
41
Where is Leptospirosis most prevalent?
- 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
What are the two phases of Leptospirosis?
1) febrile influenza-like illness 2) Disseminated phase if infection is not resolved - Meningitis - Eye infection - Jaundice - Renal failure - Rash
43
How is Leptospirosis diagnosed?
- Hx - Culture is v. difficult - Serology is employed to confirm infection
44
How is Leptospirosis treated?
PCN | Ampicillin
45
How is Leptospirosis prevented?
Limiting exposure to animal urine
46
What is the causative organism of Tularemia?
Francisella tularensis
47
List the characteristics of Francisella tularensis.
- Small, slow-growing, aerobic, Gram-negative coccobacilli - Difficult to grow in culture - Intracellular pathogens of monocytes & macrophages
48
What virulence factors are associated with Francisella tularensis?
LPS Polysaccharide capsule Intracellular pathogen *Prevents fusion of the phagosome-lysosome and acidification-->Cell-mediated activation is crucial for resoltuion of infection
49
Where is Tularemia most commonly seen?
Primarily in the Northern Hemisphere (Oklahoma, Missouri, Arkansas) - Acquired by inhalation of infected blood aerosol when skinning animals - Ingestion of contaminated meat
50
What are the reservoirs for Tularemia?
Wild mammals
51
What is the vector for Tularemia?
Hard-shell ticks
52
What is the difference between summer & fall/winter Tularemia?
``` Summer= ticks Winter= small game ```
53
What are the three types of Tularemia, and what are they dependent on?
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
What are the symptoms of Ulceroglandular Tularemia?
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
What are the symptoms of Oculoglandular Tularemia?
This is caused by direct inoculation of Fraceisella tularemia into the eye - Painful conjunctivitis with swollen cervical lymph nodes
56
What are the symptoms of Pneumonic Tularemia?
This is caused by inhalation of Fraceisella tularemia - Causes pneumonitis & eventually sepsis - High rate of mortality and morbidity
57
How is Tularemia diagnosed?
- Hx - Serology and molecular techniques - Culture is slow and difficult *Must inform lab of suspected case
58
How is Tularemia treated?
Gentamicin
59
How is Tularemia prevented?
- Prevent tick bites | - Hunter education i.e. precautions when skinning animals
60
What is the causative organism of the Plague?
Yersinia pestis
61
List the characteristics of Yersinia pestis.
- Gram negative rod - Non-motile - Produces a PROTEIN capsule
62
What is the difference between the appearance of Yersinia Pestis on Giemsa stain & Gram stain?
Gram= red (negative) Geimsa= purple with "closed safety pin" morphology
63
What are the virulence factors associated with Yersinia pestis?
- Protein capsule - LPS 3x plasmids associated with virulence - Biofilm formation - Enhanced resistance to macrophage killing - Complement resistance
64
What animals serve as reservoirs for Yersinia pestis?
- Mostly rodents | - Rat fleas
65
What is the most important animal reservoir of Yersinia pestis in the US?
Prarie dogs
66
How is Yersinia pestis transmitted?
- Bite from infected fleas - Bites & scratches from cats that killed infected rodents - Inhalation of aerosol Human-->human is possible
67
What are the symptoms of Bubonic plague.
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
What is pneumonic plague?
Inhalation of respiratory droplets from an infected person or animal (Yersinia pestis)
69
What are the symptoms of Pneumonic plague?
- Fever, headache, myalgias & respiratory signs - Progresses rapidly to symptoms of hemoptysis, resp. distress, cardiopulmonary insufficiency, cyanosis, and circulatory collapse 100% mortality
70
How is plague diagnosed?
History
71
How is plague treated?
Streptomycin

Microbiology (49 decks)

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