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

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Flashcards in Exam #8: Zoonotic & Vector Borne Bacterial Infections I Deck (71):
1

How is zoonosis prevented & controlled?

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.

2

List the zoonotic bacteria that are considered bioterrorism agents.

- Anthrax
- Brucellosis
- Meliodosis
- Tularemia
- Plague

3

List the characteristics of Anthrax.

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

4

What virulence factors is associated with Anthrax?

- Protein capsule, which is unique--others are polysaccharide
- Protective antigen (like B) with either Lethal toxin or Edema toxin associated with it

5

What is the function of protective antigen?

Acts like B-subunit, binding

6

What is the mechanism of Lethal Toxin?

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

7

What is the mechanism of Edema Toxin?

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

8

Describe the pathenogenesis of Anthrax.

- 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

9

What is Anthrax a primary disease of?

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

10

How is Anthrax prevented?

Vaccine in both animals and humans

11

What are the three types of Anthrax disease?

1) Inoculation
2) Inhalation
3) Ingestion

12

What is inoculation anthrax?

Direct inoculation of spores into open cuts or wounds
- Spores from soil, animal fur, hides, wool, or skin

13

What is inhalation anthrax?

Inhalation of spores
- Bioterrorism
- Previously called "wool-sorters disease"

14

What is ingestion anthrax?

Ingestion of spores

15

Describe the progression of Cutaneous anthrax.

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

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

16

Describe the presentation of inhalation anthrax.

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

17

Describe the presentation of gastrointestinal anthrax.

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%

18

How is gastrointestinal anthrax acquired?

Ingesting contaminated meat (likely with black eschar)

19

How is anthrax diagnosed?

- Clinical signs
- History
- Microscopy
- Culture

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

20

How is cutaneous (non-bioterrorism) anthrax treated?

Amoxacillin

21

How is inhalation, gastroinestinal, or bioterrorism anthrax treated?

- Doxycycline or Ciprofloaxcin with 2x additional antibiotics

22

What is is causative organism of Brucellosis?

Brucella

23

List the characteristics of Brucella.

- Gram negative coccobacilli
- Intracellular pathogen

*Requires specialized media for culture

24

How is Brucella transmitted?

Aerosol or ingestion of
- Contaminated food
- Direct contact with infected animal

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

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