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الرحيم الرحمن الله بسم
GENUS:BORDETELLA
Prof. Khalifa Sifaw Ghenghesh
Small, Gram-negative coccobacilliStrict aerobes. X and V factors not required for growthThree species: – B. pertussis, – B. parapertussis– B. bronchiseptica
Bordetella species
Bordetella bronchiseptica Leifson flagella stain
Scanning electron micrograph of Bordetella bronchiseptica
Bordetella pertussis
Whooping Cough– Paroxysmal coughing
Require blood, or starch or charcoal for growth– Bordet-Gengou medium (BGM)
Strict aerobeOptimal temp. > 35-36oC
ANTIGENICITY
3 Major Agglutinogens >1, 2 and 3
Detected by using adsorbed, single-agglutinin sera3 serotypes pathogenic to man– Type 1,2– Type 1,3– Type 1,2,3
All 3 have a role in immunity
Virulence Factors
Pertussis toxin (PT): an exotoxin which enters target cells and activates their production of cAMP, a molecule that acts as a second messenger in cell protein synthesis regulation Tracheal cytotoxin: causes ciliated epithelial cell destruction Hemoagglutinin: a cell surface protein which helps the bacterium bind to the host cell surface
PATHOGENESIS
highly contagious bacteriumNon-invasive diseaseMan > only natural hostIncubation period >> 1-2 weeksEnters respiratory tract via inhalation > binds to and destroys the ciliated epithelial cells of the trachea and bronchi.Symptoms last for many weeks
LABORATORY DIAGNOSIS
1. Bacterial Culture:Specimen:– Pernasal swab on flexible wire– Specimens on several successive days>
higher isolation rates.– Transport media should not be used
Culture:– Immediately on BGM– Incubate for at least 1 week
Identification:– Serological
2. Detection of Bacterial AntigensBordetella antigens in serum and urine using specific antiserumImmunofluorescence Technique:– Bacteria in nasopharyngeal
secretions labelled with fluorescein-conjugated antiserum > examined with ultraviolet microscopy.
3. Detection of Bordetella Antibody:Sera and nasopharyngeal secretions examined for Ab > Agglutination Tests, ELISA
Bordetella pertussisBordetella pertussis
TREATMENT
Erythromycin– For 2 weeks– May reduce the severity of
illness if given before paroxysmal stage.
– No clinical effect when the infection is established
– May be given to protect non-vaccinated infants
CONTROL
Vaccination: – Safe and >90% effective.– Adsorbed vaccine (i.e. with adjuvant).- Contains all 3 agglutinogens.- Minimum 3 doses.- Minor adverse reactions:
- Erythema and local swelling, slight feverishness
- Possible neurological sequelae
- Acellular pertussis vaccine
Bordetella parapertussis – a respiratory pathogen that
can cause mild pharyngitis.
Bordetella bronchiseptica– a cause of pneumonia, otitis
media, and other respiratory infections in animals.