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Infectious Agents > Mannheimia > Flashcards

Mannheimia Flashcards

1
Q

Pasteruella pneumotropica

A

Commensal in laboratory rodents

  • rats and mice are primary carriers
  • transmitted via direct contact
  • does not survive in environment
  • conjunctivitis, rhinitis, otitis, cervical lymphadenitis
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2
Q

Capsular antigens are determined by a _______ in M. haemolytica

A

Number

- all begin with the letter A

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3
Q

Growth properties of M. haemolytica

A
  • grows on MacConkey agar
  • beta hemolysis
  • indole negative
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4
Q

Virulence factors of M. haemolytica

A
  • LPS: long O chain, endotoxin to complex with leukotoxin to stabilize leukocytic activity
  • capsule: inhibits complement, phagocytosis, intracellular killing, and enhances neutrophil recruitment and adhesion to alveolar epithelium
  • fimbriae: enhance colonization of URT
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5
Q

Leukotoxin

A

Poreforming cytolysin that affects ruminant leukocytes and platelets by altering function at low levels and causing lysis at high levels

  • required for BRD lesions!!
  • RTX family of cytolytic toxins
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6
Q

Leukotoxin prefers _____

A

Neutrophils over mononuclear cells

- stimulates release of IL-1 and TNF-alpha from mononuclear cells

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7
Q

What are the different functions of leukotoxin at a high versus low dose?

A
  • low dose: activates PMNs and stimulates degranulation
  • high dose: neutrophil lysis due to membrane disruption
  • higher dose: induces neutrophil apoptosis
    = massive inflammatory cell recruitment and inflammatory mediator release, tissue destruction
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8
Q

M. haemolytica is the primary agent of ________ in cattle

A

Bovine respiratory disease (shipping fever)

  • bronchopneumonia may or may not be present
  • A1, sometimes A2 (common in normal calves before shipment)
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9
Q

M. haemolytica also causes ______ and ______

A

Mastitis in cows and broncopneumonia and mastitis in sheep

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10
Q

Treatment of M. haemolytica

A

Same as P. multocida

  • M. haemolytica and P. multocida combination bacterins are inconsistent
  • only prevention is good management
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11
Q

Bibersteina trehalosi

A
  • septicemic pasteurellosis in feeder lambs (5-12 months)
  • resembles bovine hemorrhagic septicemia w/out intestinal involvement
  • lower morbidity rate
  • stress associated
  • found in tonsils of carrier sheep
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12
Q

Avibacterium paragallinarum

A

Requires V factor (NAD)

  • will grow on blood agar with staph streak
  • forms small colonies at 24-48 hrs
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13
Q

A. paragallinarum disease

A

Infectious coryza

  • occurs in growing chickens or layers
  • nasal discharge, sneezing, facial edema, conjunctivitis, lacrimation
  • anorexia and diarrhea
  • acute or chronic form
  • leads to septicemia and arthritis with secondary bacterial infection
  • increased culls and decreased egg production
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14
Q

A. paragallinarum diagnosis

A

Difficult to diagnose via culture due to slow growth and fastidious nature (is overgrown)

  • serologic detection of serum antibodies by agglutination
  • PCR detection is effective
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15
Q

A. gallinarum

A

Commensal in URT of chickens

- occasionally causes a low grade respiratory infection in chickens

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16
Q

Actinobacillus

A

Small, GN rod, facultative anaerobes, nonmotile

- resemble pasteurella morphologically and biochemically

17
Q

Principle species of actinobacillus

A
  • pleuropneumoniae: swine pleuropneumonia
  • suis: septicemia in young pigs
  • lignierseii: bovine actinomycosis
  • equuli: sleepy foal disease
  • capsulatus: arthritis in rabbits
18
Q

What is the only specie of actinobacillus that is not a commensal?

A

Pleuropneomoniae

- occurs as a primary pathogen

19
Q

A. pleuropneumoniae disease characteristics

A

Serofibrinous pleuritis and fibrinous pneumonia

  • occurs in 2-6 month olds
  • fever, anorexia, acute respiratory distress, death in 24 hrs
  • concurrent septicemia, meningitis, arthritis
  • up to 24% mortality
20
Q

A. pleuropneumoniae virulence factors

A
  • LPS
  • capsule: antiphagocytic, required for virulence, designated by a number
  • 4 RTX toxins: Apxl, Apxll, Apxlll, ApxlV
21
Q

What is responsible for lung pathology?

A

RTX toxins

  • lyse macrophages and neutrophils at high doses, activate and cause degranulation at low doses
  • lyse alveolar epthelial cells and erythrocytes
  • Apxl is most cytolytic, followed by Apxlll, and Apxll
22
Q

What does A. pleuropneumoniae require for growth?

A

NAD

- beta hemolytic

23
Q

Capsular types

A

1-12

  • serotypes 1 and 5 are most common in North America
  • 2 is common in Europe
24
Q

Antibodies against RTX

A

Protective, but not effective

  • bacterins only provide partial protection
  • live attenuated (nonencapsulated) strains are effective, produce RTX toxins in native state
25
Q

In closed swine production facilities, what 2 pathogens emerged?

A
  • suis

- haemophilus

26
Q

A. suis

A

Early colonizer of neonatal pigs

  • sometimes occurs in adults
  • opportunistic, causes sudden death, dyspnea, cough, fever, neurological signs, abortion, cyanosis, diffuse hyperemia, petechiations on skin
27
Q

A. suis virulence factors

A
  • LPS
  • capsular polysaccharide
  • 2 RTX toxins (less virulent than A. pleuropneumoniae)
28
Q

A. lignieresii

A

Commensal of the oral cavity and pharynx of ruminants

  • cattle causes sporadic endogenous disease
  • direct inoculation into submucosal tissues due to abrasions
29
Q

A. lignieresii in cattle

A

Chronic granulomas in subq tissues of head and neck

  • clusters with bacteria surrounded by neutrophils and granulomatous inflammation
  • firm nodules with ulcerations and exudate of thick white/green pus containing small granules
  • *wooden tongue**
30
Q

A. lignieresii in sheep

A

Suppurative infections around head and neck, sometimes mammary
- no tongue involvement!

31
Q

A. lignieresii diagnosis

A

Small GN rods within small gray to white sulfur granules

- definitive diagnosis by biochemicals only

32
Q

A. lignieresii treatment

A
  • advanced cases are left untreated
  • surgical drainage, broad spec antibiotics or sulfonamide
  • Kl per os, requires prolonged treatment
33
Q

A. equuli

A

Commensal of GIT and URT of horses, repro tract of mares

  • *sleepy foal disease**
  • transmission thru in utero or thru ingestion, umbilicus, or respiratory tract during/immediately after birth
34
Q

A. equuli pathogenicity

A

Foals develop disease within hours to days of birth

  • associated with colostrum deprivation
  • acute form produces enteritis
  • sub-acute to chronic form produces septic nephritis, meningitis, pneumonia, arthritis
  • mature horses: lameness, infected aneurysms, abortion
35
Q

A. equuli diagnosis

A
  • specimens: affected tissues, blood, and feces
  • colonies are mucoid, some beta hemolytic
  • biochemical features necessary for diagnosis

Infectious Agents (44 decks)

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