Exam 4: Pasteurella, Mannheimia, Actinobacillus Flashcards
What is Pasteurella pneumotropica a common commensal in?
Laboratory rodents
What are primary carriers of Pasteurella pneumotropica?
Rats and mice
How is Pasteurella pneumotropica transmitted?
By direct contact
It does not survive long in the environment
What are the symptoms of Pasteurella pneumotropica?
Usually asymptomatic in immunocompetent hosts, but can cause disease in immunocompromised or stressed animals
What can Pasteurella pneumotropica cause?
Conjunctivitis
Rhinitis
Otitis
Cervical lymphadenitis
What was Mannheimia haemolytica formerly?
Pasteurella haemolytica biotype A
What are the 12 different serotypes of M. haemolytica based on?
Capsular polysaccharides
What does M. haemolytica grow on?
MacConkey agar
What does M. haemolytica produce on MacConkey agar?
Beta hemolysis
Indole negative
Describe lipopolysaccharide as a virulence factor of M. haemolytica
Long O side chains
Endotoxic
Complexes with leukotoxin to enhance and stabilize leukocytic activity
Describe capsular polysaccharide as a virulence factor of M. haemolytica
Inhibits serum killing, phagocytosis, and intracellular killing, and enhances neutrophil recruitment and adhesion to alveolar epithelium
Describe fimbriae as a virulence factor of M. haemolytica
May enhance colonization of URT
Describe leukotoxin as a virulence factor of M. haemolytica
Poreforming cytolysin that affects ruminant leukocytes and platelets by altering function at low levels but causing lysis at high levels
What is leukotoxin specific for?
Bovine peripheral leukocytes
What does leukotoxin prefer?
Neutrophils over mononuclear cells
What does leukotoxin bind to?
CD18 on surface of bovine leukocytes
What happens with a low dose of leukotoxin?
Activates PMNs and stimulates degranulation
What happens with a higher dose of leukotoxin?
Induces neutrophil apoptosis
What happens with a high dose of leukotoxin?
Neutrophil lysis due to membrane disruption
What does leukotoxin stimulate?
Release of IL-1 and TNF from mononuclear cells
What do lymphocytes undergo with leukotoxin?
Apoptosis and necrosis
What do platelets have with leukotoxin?
Increased adhesion
What is the result of leukotoxins?
Massive inflammatory cell recruitment and inflammatory mediator release, tissue destruction
In cattle, what is M. haemolytica the primary agent of?
Bovine respiratory disease or shipping fever
What is the most common BRD agent?
Serotype A1, sometimes A2 which is the most common type in normal calves before shipment
What are other tings that can be caused by M. haemolytica?
Mastitis in cows (A6)
Broncopneumonia and mastitis in sheep (A1, A6)
Describe the treatment of M. haemolytica
Same as for P. multocida
M. haemolytica and P. multocida combination bacterins are inconsistent. Recombinant leukotoxin does not protect cattle
What does Avibacterium paragallinarum require?
V factor (NAD)
What will A. paragallinarum grow on?
Blood agar with Staphylococcous streak
What does A. paragallinarum cause?
Infectious coryza, which is an acute contagious upper respiratory infection in chickens
What can A. paragallinarum occur in?
Growing chickens or in layers
What are clinical signs of A. paragallinarum?
Nasal discharge Sneezing Facial edema Conjunctivitis Lacrimation Anorexia Diarrhea
What is the morbidity and mortality like with A. paragallinarum?
High morbidity
Low mortality
What can A. paragallinarum be complicated by and what does that lead to?
Secondary bacteria and lead to septicemia and arthritis
What is the result of A. paragallinarum?
Increased culls and decreased egg production
Why is the diagnosis of A. paragallinarum by culture difficult?
It is slow growing and fastidious
It is easily overgrown
How is A. paragallinarum diagnosed?
Serologic detection of serum antibodies by agglutination
PCR detection is effective
What is A. gallinarum a commensal in?
URT of chickens
What does A. gallinarum occasionally cause?
Low grade respiratory infections in chickens
What are members of the genus Actinobacillus like?
Small GN, facultatively anaerobic, nonmotile rods
What does Actinobacillus resemble morphologically and biochemically?
The genus Pasteurella
What are the principle species of Actinobacillus and what do they cause?
A. pleuropneomoniae: swine pleuropneumonia A. suis: septicemia in young pigs A. lignierseii: bovine actinomycosis A. equuli: sleepy foal disease A. capsulatus: arthritis in rabbits
What do all species of Actinobacillus occur as?
Commensals
What is A. pleuropneomoniae associated with?
Respiratory tracts of sick or recovered animals
What does A. pleuropneomoniae cause?
Acute, subacute, or chronic pleuropneumonia of swine
What is A. pleuropneomoniae disease characterized by?
Serofibrinous pleuritis and fibrinous pneumonia
What are the virulence factors of A. pleuropneomoniae?
LPS; long O side chains; adhesive properties
Capsular polysaccharide: antiphagocytic, required for virulence
Fimbriae
RTX toxins
What are the RTX toxins responsible for lung pathology with A. pleuropneomoniae?
ApxI, ApxII, ApxIII, and ApxIV
Describe thee growth of A. pleuropneomoniae
Beta hemolytic
Requires NAD for growth
What are the serotypes of A. pleuropneomoniae most common in North America? Europe?
Serotypes 1 and 5
Serotype 2
How are the capsular types of A. pleuropneomoniae identified?
Numbered 1-12
What are the virulence factors of A. suis?
LPS
Capsular polysaccharide
2 RTX toxins similar to Apx I and Apx II
What kind of pathogen is A. suis?
Opportunistic
What is A. lignieresii a commensal organism of?
The oral cavity and pharynx of ruminants
What does A. lignieresii cause in cattle?
Sporadic endogenous disease
Describe sporadic endogneous disease caused by A. lignieresii
Usually a result of direct inoculation into submucosal tissues
Chronic granulomas form in SubQ tissues of head and neck
Firm nodules develop with green pus
Tongue protrudes from mouth
Granulomatous lesions spread to lymph nodes and lungs
What does A. lignieresii cause in sheep?
Suppurative infections around head and neck, sometimes mammary
What is A. equuli a commesal organism of?
The GI tract and URT of normal horses
Reproductive tract of mares
What does A. equuli cause?
Sleepy foal disease in neonatal horses
What is the transmission of A. equuli though to be through?
In utero or ingestion, umbilicus, or respiratory tract during or immediately after birth