Lecture 23 Bordetella

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.