Haemophilus

Question 1

What 3 genera make up the family Pasteurellaceae?

Answer 1

1. Haemophilus (Histophilus, Glasserella, Avibacterium)
2. Actinobacillus
3. Pasteurella (Mannheimia)

Question 2

When is Pasteurellaceae infection most common?

Answer 2

opportunistic pathogen of farm animals —> prior infection, stress

Question 3

What is the structure of Haemophilus? How does it grow in TSI media?

Answer 3

Gram-negative coccobacullus

weakly fermentative —> orange, weak acid

Question 4

What 2 factors are required for Haemophilus growth? What kind of parasite is it considered?

Answer 4

(blood factors)
1. X factor - hemin
2. V factor - NAD coenzyme in ETC for respiration

obligate parasite of host mucosal surfaces —> urogenital tract and upper respiratory tract only

Question 5

What are the main 3 Haemophilus species and their hosts?

Answer 5

1. Avibacterium paragallinarum - chicken
2. Glasserella parasuis - pigs
3. Histophilus somni - cows

Question 6

What does Glasserella parasuis require for growth? What affects serotyping?

Answer 6

V (NAD) factor only

capsule and lipooligosaccharide (LOS)

Question 7

What is Glasserella parasuis the causative agent of? In what animals is it most common? When are they most susceptible?

Answer 7

Glasser’s Disease - polyserositis

young pigs (nursery mortalitiy)
- pigs already infected with PRRS or are from SPF herds

Question 8

What are 2 characteristics of Glasser’s Disease?

Answer 8

1. polyserositis, fibrinous inflammation of serous membranes (pericardium, liver)
2. purple ears due to bacteremia

Question 9

How can Glasser’s Disease affect older pigs? When is it most common for older pigs to become infected? What are 3 differentials?

Answer 9

• respiratory disease
• chronic pleurisy

following previous infection of mycoplasma or virus

P. multocida, Bordetella, Actinobacillus

Question 10

What are the 4 main virulence factors of Glasserella parasuis? What does it lack?

Answer 10

1. capsule
2. lipooligosaccharide (endotoxin)
3. adherence factors (serous membranes)
   4 membrane proteins

exotoxins

Question 11

What are adherence factors used for in Glasserella parasuis disease? What are some examples?

Answer 11

host colonization by attachment to mucosal epithelial cells

pili, LOS, membrane proteins

Question 12

What are lipooligosaccharides? How does each part of it affect virulence of Glasserella parasuis?

Answer 12

polysaccharide lacking O side chains in the LPS of Haemophilus

lipid A = endotoxic —> chronic inflammation —> fibrin
more oligosaccharide —> antigenic

Question 13

What are 2 compromising factors of Glasserella parasuis infection?

Answer 13

1. viral infection associated with respiratory disease
2. stress is associated, but not required as newborn pigs are already compromised

Question 14

What is Glasser’s Disease predominantly the result of?

Answer 14

host inflammation —> trying to remove a pathogen it cannot

Question 15

How is immunity to Glasserella parasuis obtained?

Answer 15

mediated by antibodies to the capsule (15 types of capsules!)
- humoral immunity is most important

Question 16

What are 2 vaccination options for Glasserella parasuis? In what 3 ways is it treated/controlled?

Answer 16

1. bacterins (killed organisms) effective against homologous serotype - not very long-lasting
2. attenuated live

• antimicrobials (dosen’t tend to be AMR)
• intentional exposure at 3-5 days of age with low-dose of less virulent serotypes (RISKY)
• protection through maternal antibodies

Question 17

What is Avibacterium paragallinarum specific for? What dose it require for growth? How does it grow on blood agar?

Answer 17

avian species

V (NAD) factor only

non-hemolytic

Question 18

What is Avibacterium paragallinarum the causative agent of? What are 2 symptoms?

Answer 18

Fowl coryza (acute rhinitis)

1. inflammation of turbinates and sinus epithelium
2. air sacculitis

Question 19

What is the morbidity and mortality of Fowl coryza?

Answer 19

(Avibacterium paragallinarum)
high morbidity, low mortality

Question 20

Fowl coryza, airsacculitis:

Answer 20

(Avibacterium paragallinarum)

Question 21

Fowl coryza, nares and URT inflammation:

Answer 21

Question 22

What are the 4 major virulence factors of Avibacterium paragallinarum? What is not recognized?

Answer 22

1. capsule
2. lipooligosaccharide
3. adherence factors
4. membrane proteins

exotoxins

Question 23

What are 2 compromizing factors of Avibacterium paragallinarum infection? What is disease the result of?

Answer 23

1. viral or mycoplasma infection
2. stress

host inflammation

Question 24

How is immunity to Avibacterium paragallinarum acquired?

Answer 24

mediated by antibodies to capsule
- humoral immunity most important

Question 25

What is the best type of vaccination for Avibacterium paragallinarum?

Answer 25

bacterins against serotypes A, B, and C ---> only can work for one serotype - produced antibodies against capsule

Question 26

What species make up Histophilus somni? What are they specific for?

Answer 26

Haemophilus somnus, Haemophilus agni, Histophilus ovis bovines and sheep

Question 27

What does Histophilus somni require for growth? How do colonies grow on agar?

Answer 27

neither X or V factors ---> requires blood and CO2 colonies are yellow when picked up with a white swab and are weakly hemolytic or nonhemolytic

Question 28

Where is Histophilus somni typically found? How does it cause infection?

Answer 28

ruminant genital and respiratory tract dissemination via bloodstream and localizes into the brain, heart, and joints, typically due to inflammation of the endothelium

Question 29

What is hallmark of Histophilus somni infection? What is required to cause infection?

Answer 29

vasculitis due to inflammation of endothelium stress AND viral infection ---> feedlot disease, not common in cows in open pastures

Question 30

What are the 2 most common diseases that Histoophilus somni cause? 4 others?

Answer 30

1. pneumonia (BRDC, shipping fever) 2. myocarditis (bioflim) 3. thrombotic meningoencephalitis 4. reproductive failure 5. arthritis 6. bacteremia

Question 31

What are some common signs of thrombtic meningoencephalitis caused by Histophilus somni?

Answer 31

- eye drooping - nasal discharge - depression - uveitis

Question 32

What causes myocarditis in Histophilus somni infection?

Answer 32

bacteria aggregate into biofilm structures and adhere to venous endothelium with fibrin and neutrophil invasion

Question 33

When does Histophilus somni typically form biofilms? What is the purpose?

Answer 33

under most growth conditions and in host tissue more resistant to antibiotics and host defenses, but induces less inflammation

Question 34

What is produced by Histophilus somni when in bioflin aggregates?

Answer 34

exopolysaccharide

Question 35

What is the major virulence factor of Histophilus somni? What does it do?

Answer 35

lipooligosaccharide endotoxin causes apoptosis of endothelial cells, leading to vasculitis

Question 36

How does the phase of lipooligosaccharides in Histophilus somni alter in vivo?

Answer 36

antigenic epitopes change and enable the bacteria to evade host immunity by taking up sialic acid (which is commonly found in the host)

Question 37

What additional receptor is present on Histophilus somni? What does it do?

Answer 37

IgG Fc receptors (IbpA) - allows bacterium to bind the Fc region of IgG, which protects it from host defenses and contains a toxic motif toxic to eukaryotic cells

Question 38

How does Histophilus somni survive within phagocytic cells?

Answer 38

inhibits phagosome-lysosome fusion

Question 39

What is the toxic motif present in IgG binding protein A of Histophilus somni target?

Answer 39

bovine endothelial cells and macrophages ---> vasculitis

Question 40

What are the 2 major compromising factors of Histophilus somni? What causes disease?

Answer 40

1. stress 2. previous infection host inflammation

Question 41

What is Histophilus somni virulence largely due to? What factors most into passive immunity?

Answer 41

avoiding host immune response within phagocytic cells antibodies to fic motif

Question 42

What is the best route of vaccination available for Histophilus somni? How is it limited?

Answer 42

bacterins - best for TME phase variation and IgG binding proteins on bacteria

Question 43

What mediates host specificity of Histophilus somni? Why can't the bacteria infect other animals?

Answer 43

adherence and iron acquisition host-specific bacteria obtain iron from host transferrin and can only use that specific transferrin

Question 44

What is unique about the process of isolating Haemophilus species?

Answer 44

many are part of the normal flora, so isolates need to be from sterile sites or in a pure culture on chocolate agar - include NAD and blood/CO2 (H. somni)

Question 45

What type of serological test is used for Heamophilus species identification?

Answer 45

complement fixation test - slide or tube agglutination isn't very sensitive - ELISA for outer membrane protein or exopolysaccharide

Question 46

How are Haemophilus infections typically treated?

Answer 46

antibiotics - use least expensive - AMR can occur, susceptibility test needed