Transcript
Bordetella bronchiseptica
Supervisor: Dr. Monadi
Compiler : Sina Taefehshokr
Veterinary Medicine Faculty
Islamic Azad University Tabriz Branch, Iran
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In 1906, Jules Bordet and Octave Gengou (two famous Belgian bacteriologist : 1875-1957) discovered the microbe that causes whooping cough (Bordet-Gengou bacillus or Bordetella pertussis).
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Scientific classification of the bacterium
Kingdom: Bacteria Phylum: Proteobacteria Class: Betaproteobacteria Order: Burkholderiales Family: Alcaligenaceae Genus: Bordetella
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Bordetella Characteristics
• Small, Gram-Negative rods and coccobacilli• Aerobic, Catalase, and Oxidase-Positive,
Do not Ferment Carbohydrates• They are both Motile and Nonmotile
species• Encapsulated and does not produce spores
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• B. pertussis• B. avium• B. bronchiseptica• B. hinzii• B. holmesii• B. parapertussis• B. petrii• B. trematum• B. ansorpii
Bordetella Species
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Virulence factors of Bordetella bronchiseptica and B. avium.
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Bordetella species of veterinary importanceand disease conditions with which they are associated.
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Main Pathogenic Species
B. PertussisCauses whooping cough (Pertussis) in humans
B. AviumCauses turkey coryza or avian bordetellosis
B. BronchisepticaNatural hosts are animals; causes respiratory disease including infectious atrophic rhinitis (IAR) of pigs. It’s also one of the causative organisms of Kennel cough of dogs
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Leifson flagella stain Scanning electron micrograph
B. Bronchiseptica
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B. Bronchiseptica Genome structure
• Circular chromosome consisting of approximately 5,338,400
base pairs
• Of the circular chromosome, 68.07% of the composition are GC
complements
• About 3,000 genes are shared by its closest relatives, B.pertussis
and B. parapertussis
• A small labile plasmid is found in most strains and is believed to
be crucial in inferred antibiotic resistance
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B. Bronchiseptica Cell structure and metabolism
• The inner cell membrane which surrounds the cytoplasm is tri-laminar
• The cytoplasm matrix is rich in ribosomes
• The nuclear zone contains DNA present in a network of fibers and
undefined bodies
• The whole organism seems to be encapsulated in a polysaccharide
capsule
• May or may not have a flagella dependent on if environment stimuli
signals for need of motility
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B. Bronchiseptica Ecology
• Commensal in upper respiratory tract of dogs, cats, swine, rabbit,
horses, guinea pigs, rats
• Colonizes the tracheal area and often times induces other
respiratory illnesses by making the host more susceptible to them
• Infections in domestic and lab animals have led to a huge
economic loss through veterinary costs, disfigurement, loss in
sales, vaccine research and development, drug costs, etc
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B. Bronchiseptica Pathogenesis
The bordetellae exhibit phase changes, which correlatewith virulence and are identifiable by colonial appearance.Expression of virulence is regulated by a two-componentsignal transduction system encoded by the BvgAS locus.The avirulent phase occurs at 25°C whereas at 37°CBvgAS activates the expression of many virulence genes.Virulence is mediated by several factors, which can bebroadly classified as adhesins or toxins. Adhesins include afilamentous haemagglutinin, pertactin and fimbriae whichallow attachment to the cilia of the upper respiratory tract
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Diagnostic procedures
• Specimens for laboratory examination include nasal swabs,tracheal aspirates and exudates.• Bordetellae are cultured on blood agar and MacConkey agaror on selective media. Plates are incubated aerobically at37°C for 24 to 48 hours.• Identification criteria for isolates:– Colonial appearance on blood agar or selective media– Growth on MacConkey agar– Biochemical profile– Slide haemagglutination tests correlating with thevirulence of isolates.• Serological tests which have been developed are of limiteddiagnostic value.• PCR procedures have been developed for detection ofbordetellae in clinical specimens, including realtime andmultiplex assays
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Treatment and control
• Broad-spectrum antibiotics early in the course of diseasemay be beneficial.• Commercially available bacterins and modified live vaccinesmay be used in susceptible flocks.• Thorough cleaning and disinfection of turkey houses after anoutbreak of disease are essential for the elimination of B.avium.
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References
Bemis, D.A. (1992). Bordetella and mycoplasmarespiratory infections in dogs and cats. Veterinary Clinicsof North America: Small Animal Practice, 22, 1173–1186.
Blackall, P.J. and Doheny, CM. (1987). Isolation andcharacterisation of Bordetella avium and related speciesand an evaluation of their role in respiratory disease inpoultry. Australian Veterinary Journal, 64, 235–239.
Buboltz, A.M., Nicholson, T.L., Weyrich, L.S. and Harvill,E.T. (2009). Role of the type III secretion system in ahypervirulent lineage of Bordetella bronchiseptica.Infection and Immunity, 77, 3969–3977.
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