Pasteurellaceae Flashcards
(13 cards)
Pasteurella belong to the family Pasteurellaceae. What are some other genera in this family?
- Mannheimia (M. haemolytica - used to be P. haemolytica). Usually talk about Pasteurella and Mannheimia together
- Haemophilus
- Histophilus
- Actinobacillus
What are some general characteristics of Pasteurella?
- Gram negative cocco-bacilli, bipolar staining
- Facultative anaerobes
- non-motile
- Biochemically active - oxidase and catalase positive
- Commensals of mucosal membrane of respiratory tract, and mouth
- Respiratory infections and septicemia, also skin infections (bites, licking at surgical wounds)
- Encapsulated - low antigenicity due to resemblance of hyaluronic acid
- Exotoxins - dermonectrotoxin from capsule (P. multocida). RTX toxin (a labile leukotoxin) (M. haemolytica)
How is diagnosis of Pasteurella made?
- Isolation
- Gram or Giemsa stain - bipolar staining
- P. multocida - characteristic odor
- Hemolysis - M. haemolytica, B. trehalosi
- Production of indole - P. multocida
- change in color of broth, indicating the ability to convert tryptophan to indole (tryptophanase +)
Pasteurella induced disease has three manifestations. What are these?
- Respiratory tract
- pneumonia, atrophic rhinitis
- M. haemolytica, P. multicida
- stress plays a role in onset of this dz - commensals allowed to overgrow and infect
- Septicemia
- iron scavenging systems crucial - transferrin binding proteins
- Trauma-associated
- ususally when commensals in the mouth are inoculated into the site of infection - bites, licking surgical sites
Why are the capsules of P. multocida and M. haemolytica poorly immunogenic?
What is the role of LPS in the bacterial cell wall?
- capsules are similar to hyaluronic acid
- LPS
- protection via the carb moiety
- induction of inflammation via lipid A component
What are some general characteristics of Haemophilus?
- gram negative cocco-baccili
- capable of fermenting sugars
- fastidius - needs hemin or NAD, or both
- X-factor = hemin
- V-factor = NAD
- commensals of mucous membranes or respiratory tract, urogenital tract, and sometimes GIT
What are some dz’s that Haemophilus cause, and in what animal species?
- Fowl - infectious Coryza (inflammation of upper airways)
- Pigs - Glasser’s dz (inflammation of serous surfaces = swollen joints)
- Sheep - septicemia in lambs
- Cat - vaginitis, pleurisy
What are some virulence factors of Haemophilus?
- Capsule - interference of phagocytosis and protection of the outer membrane from deposition of complement complexes (MACs - membrane attack complexes)
- LPS of cell wall
- Exotoxins - some produce a weak hemolysin
- Immunogolbulin-binding proteins - bind the Fc region of immunoglobulins rendering them useless
- Proteases - destroy mucosal IgA
- IROMPs - iron regulated outer membrane proteins. These are host specific. Bind host transferrin molecules.
How is diagnosis made of Haemophilus?
- Isolation of bacteria from normally sterile sites or in pure culture from infected sites is necessary to confirm the isolate is present as a pathogen and not as normal flora
- Most isolates require NAD and will grow on Chocolate agar, or Blood agar with a streak of Staphylococcus to provide the NAD
Actinobaccili are closely related to Haemophilus. What is one major difference?
- most Actinobaccili do not require X or V factors (hemin or NAD)
- A. pleuropneumonia requires V factor
What is it about Actinobaccili that is unique about their colonies on agar/
- they are very sticky and difficult to remove
Where are Actinobacilli usually found?
What are some common types of disease?
What is a major disease caused by Actinobacilli lignieresii?
- Commensals of respiratory, alimentary, and urogenital tract
- pleuropneumonia, septicemia
- Wooden tongue in cattle
