Bordetella Flashcards
General characteristics
Small, GN, rods to coccobacilli
- aerobic
- oxidase positive
- nonfermentative
- motile and nonmotile species
- parasites of ciliated respiratory epithelium
Species
- B. bronchiseptica: animal respiratory disease
- B. pertussis: human whooping cough
- B. parapertussis: human parapertussis
- B. avium: rhinotracheitis of turkey poults
Distribution of B. bronchiseptica
Commensal of URT of dogs, cats, swine, rabbits, etc
- most common cause of respiratory infection in guinea pigs!! –> should not be housed with rabbits
Regulation
BvgAS: sensor system that detects environmental signals and turns on virulence genes
- temperature is a possible inducer
Adhesins
- filamentous hemagglutinin: required for adherence to ciliated respiratory cells and phagocytes
- fimbriae: undergo phase variation
- pertactin: outer membrane protein
Adenylate cyclase (CyaA)
Secreted by all bordetella
- necessary for infection/virulence
- low hemolytic activity
- RTX cytotoxin structure: lyse macrophages, neutrophils, lymphocytes
- intracellular toxin –> activated by calmodulin = increased cAMP
Dermonecrotic toxin
- heat labile AB toxin
- causes changes in actin cytoskeleton of affected cells and inhibition of osteoblast differentiation
- similar to P. multocida dermonecrotoxin
Pertussis toxin
AB toxin produced by B. pertussis
- ADP-ribosylating activity on activated G proteins = permanent active state
- G proteins cause increased adenylate cyclase activity = increased cAMP
Pathogenesis
Increased cAMP = increased mucus production and fluid accumulation in URT
- ciliary paralysis occurs
- ciliated epithelial cells are killed by type 3 secretion system
- loss of ciliary function = more fluid and mucus accumulation
- adheres to recruited phagocytes = phagocytosis is inhibited due to cAMP
- can survive in phagolysosomes if phagocytosed!!
Transmission
- inhalation
- endogenous or exogenous
- direct or indirect contact and fomites
Infection in dogs
Infectious tracheobronchitis = kennel cough
- one week incubation
- hacking cough
- high morbidity, low mortality
- pneumonia is rare
- persists asymptomatically for months
- disease accompanied by canine parainfluenza virus 2 or adenovirus 1 or 2
Swine
URI at 3-4 weeks of age
- sneezing and nasal discharge
- B. bronchiseptica alone is transient and self limiting
- atrophic rhinitis (with P. multocida)
- cause pneumonia in neonatal pigs 3-4 days old
Infection in guinea pigs
Catarrhal to mucopurulent exudates in URT
Diagnosis
Isolated on blood agar under aerobic conditions
- growth enhanced at 30 C
- motile peritrichous flagella –> nonmotile at 37 C
- oxidase and catalase positive
- rapid urease production
Treatment and control
- bacterin for sows and piglets
- elimination of carrier sows
- bacterins or live attenuated vaccines for dogs
- isolation of affected dogs
