Bordetella Flashcards
Classification and species?
Family: Alcaligenaceae
Genus: Bordetella
Species:
Bordetella pertussis
Bordetella parapertussis
Bordetella bronchiseptica
General characteristics? (aerobicity,motility,capsulated or not? Spore forming or not?)
Small Gram-negative coccobacilll
Strict aerobes
Non-motile (B.bronchiseptica is motile)
Capsulated
Non-spore forming
Toxins?
Pertussis toxin
Adenylate cyclase toxin
Tracheal toxin
Transmission?
Airborne droplets
Fomites
Virulence factors other than toxins?
ADHESINS:
Filamentous haemagglutinin(FHA)
Fimbriae
Pertactin
SECRETION SYSTEMS:
III and IV
Main clinical manifestations? (for each species)
B.pertussis- whooping cough
B.parapertussis- milder form of whooping cough
B.bronchiseptica- lethal pneumonia to asymptomatic carriers
whats the host for B.pertussis?
Strictly humans
Explain in 4 points pathogenesis of b.pertussis.
Filamentous HA binds to sulfatides on cilia
Colonises lung epithelial cells
Once achored, bacterium produces tracheal cytotoxin, which stops the cilia from beating.
Prevents body from clearing debris from the lungs;body responds by sending the body into a coughing fit
Explain the mode of action of pertussis toxin.
- Entry: The toxin enters cells through endocytosis (basically gets swallowed up by the cell)
- Travel Route: It moves through the cell’s internal transport system:
- Goes through the Golgi apparatus
- Passes through the ER (endoplasmic reticulum)
- Finally reaches the cell’s cytosol (inner fluid)
- Main Action: The toxin’s critical effect is that it disrupts G-protein signaling by:
- Modifying a specific part of the G-protein (called the Gi protein)
- This leads to increased cAMP (cyclic AMP) production
- Result: The increased cAMP causes multiple effects in the body, including:
- Disrupting immune cell functions
- Interfering with normal cell communication
- Affecting various cellular processes
List the stages of illness in B.pertussis.
Catarrhal stage
Paroxysmal stage
Convalescent stage
State the symptoms seen in catarrhal stage.
Lacrimation
Rhinorrhea
Mild cough
State the symptoms seen in paroxysmal stage.
5-10 coughs in one respiration (coughing fits)
Classic whoop in respiration
Desribe asymptomatic infection. ( Risk groups and symptoms)
patients:
Re-infected adult
Vaccinated children
Symptoms:
Lacrimation
Conjuctivitis
Sneezing
Complications of B.pertussis?
Encephalitis
Bronchopneumonia
Main agar that is used to culture b.pertussis?
Regan-Lowe agar
Bordet-gengou agar (Jenga!)
Describe appearance of culture.
Bordet-Gengou plate (red)— slight beta-haemolysis, smooth colonies, shiny, resemble mercury droplets
Regan-Lowe agar (black) — domed colonies, shiny, white mother-of-pear opalescence
Biochemical test? (oxidase and catalase)
Oxidase positive
Catalase positive
Treatment and vaccine?
Antibiotics: Ampicillin and azithromycin
Vaccine:
• Pertussis vaccines, initially whole-cell (DTwP), drastically reduced cases but caused side effects.
• Acellular vaccines (DTaP) replaced them, yet pertussis incidence is rising in some vaccinated populations.
