Bordetella Flashcards
➢General characteristics of Bordetella
● Gram (-ve) coccobacilli.
● Capsulated.
● Aerobic.
➢Disease caused Bordetella
Pertussis: whooping cough
stages of Bordetella
- Convalescent stage (=Recovery stage):
.) بعرف بیھا ال1. Incubation period:
● 2 weeks
● Asymptomatic.
- Catarrhal stage:
● Resembles the common cold.
● Presented with a runny nose and conjunctivitis.
● It is the most infectious stage and the best treated one.
- Paroxysmal stage (=Whooping cough stage):
● Coughing with inspiratory stridor (because of the inspiration against narrowed glottis)
● Associated with excessive production of fluid (mucus).
● This stage ends with vomiting (case Shows gradual reduction of symptoms
Why does Bordetella cause coughing
● The first line of defence in the respiratory tract is: Cillia.
● The 2nd line of defence in the respiratory tract is: Coughing.
How much paroxysmal cough if brotella in adult
severity lasting weeks 100-day cough
➢Complications of Bordetella
● Respiratory complications:
- Pneumonia and pleurisy.
● GIT complications:
- Malnutrition
- Signs of increased intra-abdominal pressure: (GI Intussusception, Hernias, Lower GI bleeding)
● CNS complications:
Anoxia (No O2 entering the brain) due to cough … etc , which results in:
- Collapse.
- Encephalopathy
- Paralysis.
- Blindness.
● Cardiovascular complications:
- Arrhythmia
- Subconjunctival haemorrhage (in the paroxysmal stage ) DDx of subconjunctival haemorrhage: infective endocarditis.
● Other complications:
- In children: Emphysema of neck.
➢Transmission of Bordetella
Respiratory droplets.
➢Pathogenesis of Bordetella
Dystrophy of cilia
➢Virulence factors of Bordetella
- Pilli:
Mediate attachment by a protein called filamentus hemeagglutinin.
- Exotoxin (pertussis toxin):
Cause ADP ribosylation of the Gi proteins: causing:
a. increase in adenylyl cyclase activity and thus cAMP levels. This results in edema of the respiratory mucosa that contributes to the severe cough of pertussis.
b. inhibition of signal transduction of chemokine receptors, resulting in a failure of lymphocytes to enter lymphoid tissue causing a striking lymphocytosis .
- Tracheal cytotoxin:
● It’s a part of its peptidoglycan
● It causes destruction of the cilia by activating nitric oxide NO.
- Adenylyl cyclase:
● It exports this enzyme which is then taken up by the phagocytes and it inhibits their bactericidal activity.
● Antibodies against the adenylyl cyclase are protective.
● Strains that don’t have adenylyl cyclase are non-pathogenic = Avirulent.
➢Diagnosis of Bordetella
- Mainly clinical (whooping cough).
- Specimen collection: Nasopharyngeal swab.
- Culture:
● Bordet Genguo medium.
● Charcoal media. (also in Legionella): mercury droplets appearance.
- Serology
- PCR
➢Treatment of Bordetella
- Supportive treatment:
● O2 therapy
● Sucking the mucus.
- Specific treatment:
Erythromycin or Azithromycin (Macrolides).
why we use macrolides على الرغم من ان لا يعالج دمار الcilia
● To decrease the number of the organism already present
● To decrease the risk of development of secondary complications.
➢Prevention of Bordetella
DTaP vaccine: The pertussis vaccine is usually given combined with diphtheria and tetanus toxoids.
➢There are 2 vaccines:
● Acellular vaccine: Contains five antigens purified from the
organism. The main immunogen in this vaccine is a genetically
inactivated pertussis toxin (pertussis toxoid).
● Killed vaccine: containing inactivated Bordetella Pertussis organism. (it’s no longer used in the U.S. because of its side effects “post vaccine encephalopathy”)
➢Chemoprophylaxis: Azithromycin.
● It is useful in prevention of disease in exposed, unimmunized individuals.
● It should also be given to immunized children younger than 4 years who have been exposed because vaccine-induced immunity is not completely protective.
