35-36- Bordetella, Francisella, and Brucella Flashcards
B. pertussis- media requirements
a) B. pertussis is susceptible to toxic substances and metabolites; therefore it must be grown on media supplemented with charcoal, starch, blood, or albumin to absorb the toxins. Also the fastidious species grow slowly in culture.
What is the role of the adhesins in B. pertussis?
i) Filamentous hemagglutinin: Required for binding to sulfated glycoproteins on membranes of ciliated cells in trachea; highly immunogenic
ii) Pertussis toxin: S2 subunit binds to glycolipid on surface of ciliated respiratory cells; S3 subunit binds to ganglioside on surface of phagocytic cells
What are the roles of the toxins in B. pertussis?
i) Adenylate cyclase: Increases intracellular level of adenylate cyclase; inhibits phagocytic killing and monocyte migration. Important for initial protection during early stages of disease.
ii) Tracheal cytotoxin: A peptidoglycan fragment that kills ciliated respiratory cells and stimulates the release of interleukin-1 (fever)
What is the catarrhal stage of B. pertussis?
: presentation similar to common cold. Peak number of bacteria is being produced. Pts are most likely to spread bacteria at this time
What is the paroxysmal stage of B. pertussis?
Whooping cough begins at this stage
What is the convalescent stage of B. pertussis?
the cough diminishes, but secondary complications can occur
What is the vaccine for B. pertussis?
b) Acellular pertussis vaccine replaced the whole-cell vaccine.
i) There are two types, one for children one for adults
ii) Both acellular vaccines contain inactivated pertussis toxin, filamentous hemagglutinin, and pertactin.
iii) Usually given with vaccines for tetanus and diphtheria (TDaP)
What is zoonosis?
a) Infectious organisms that are transmitted from animal to human or vice versa.
F. tularensis- lab features
a) F. tularensis is a gram- coccobacillus which requires cysteine for growth, and is strictly aerobic.
F. tularensis- pathogenesis
i) It is an intracellular pathogen which can survive w/in macrophages b/c it inhibits phagosome-lysosome fusion.
ii) Pathogenic strains contain a Capsule (polysaccharide rich), which protects it from complement mediated killing during bactermia phase.
iii) Does contain a low activity endotoxin.
Ulceroglandular tularemia- clinical presentation and cause
Cause- F. tularensis. painful papule develops at site of inoculation and progresses to ulceration; localized lymphadenopathy
Oculoglandular tularemia- clinical presentation and cause
Cause- F. tularensis. following inoculation into the eye (e.g., rubbing eye with a contaminated finger), painful conjunctivitis develops, with regional lymphadenopathy
Pneumonic tularemia- clinical presentation and cause
Cause-F. tularensis. pneumonitis with signs of sepsis develops rapidly after exposure to contaminated aerosols; high mortality unless promptly diagnosed and treated
Where is F. tularensis found?
N America. In rabbits and cats and hard-shelled ticks
F. tularensis- media
a) Chocolate agar and BCYE agar (cysteine supplemented agars)
