BordetellaBordetella

The genus The genus Bordetella Bordetella includes includes species which resemble species which resemble Haemophilus, but do not require X Haemophilus, but do not require X and V factors. It comprises the and V factors. It comprises the following speciesfollowing species::

Bordetella pertussisBordetella pertussis

Bordetella parapertussisBordetella parapertussis

Bordetella Bordetella bronchisepticabronchiseptica

Bordetella pertussisBordetella pertussis

Natural habitatNatural habitat:: In the respiratory tract, nasopharynx In the respiratory tract, nasopharynx

and droplet of whooping cough and droplet of whooping cough patientspatients..

MorphologyMorphology:: Gram -ve coccobacilliGram -ve coccobacilli

0.50.5 µmµm CapsulatedCapsulated non-motilenon-motile..

Cultural charactersCultural characters:: - -AerobeAerobe..

- -Primary isolation is facilitatedPrimary isolation is facilitated

by enriched mediaby enriched media

e.g. e.g. Bordet GengouBordet Gengou ( potato ( potato extract extract –– glycerin blood agar) glycerin blood agar)..

- -Can be grown on charcoal yeast Can be grown on charcoal yeast extract agar + cephalexinextract agar + cephalexin..

- -Organisms are identified by IF or Organisms are identified by IF or slide agglutination with specific slide agglutination with specific antiseraantisera..

““mercury drop” colonies of Bordetella mercury drop” colonies of Bordetella

pertussis on Bordet Gengou mediumpertussis on Bordet Gengou medium

..

Antigenic structureAntigenic structure:: - -When isolated from patients the When isolated from patients the

organism is haemolytic and organism is haemolytic and produces produces pertussis toxinpertussis toxin..

- -Heat labile capsular Ags are used Heat labile capsular Ags are used for serotyping (for serotyping (K agglutinogensK agglutinogens))

Factors involved in the Factors involved in the pathogenesispathogenesis

11 . .PiliPili:: adhere to ciliated adhere to ciliated epithelial cells of URTepithelial cells of URT..

22 . .Tracheal cytotoxinTracheal cytotoxin inhibits DNA synthesis in inhibits DNA synthesis in ciliated epithilial cellsciliated epithilial cells..

33 . .Two virulence genes Two virulence genes regulate production ofregulate production of : :

-Pertussis toxinPertussis toxin lymphocytosislymphocytosis..,..,

-Dermonecrotic toxinDermonecrotic toxin..--

Clinical presentationClinical presentation - -Bordetella pertussis is the causative Bordetella pertussis is the causative

agent ofagent of whooping coughwhooping cough, , a a disease affecting the upper repiratory disease affecting the upper repiratory mucosa mainly in childrenmucosa mainly in children..

- -TransmissionTransmission is by droplet infection (high is by droplet infection (high infectivity)infectivity)..

- - - -ClinicallyClinically:: IP: IP: 2 weeks2 weeks..The catarrhal stage: The catarrhal stage: mild coughing and mild coughing and sneezing, large number of bacteria in sneezing, large number of bacteria in dropletsdroplets..The paroxysmal stage:The paroxysmal stage: cough becomes cough becomes explosive with a characteristic whoop explosive with a characteristic whoop upon inhalation. It may be associated upon inhalation. It may be associated with vomiting, cyanosis , convulsionswith vomiting, cyanosis , convulsions..

Paroxysmal stage of Paroxysmal stage of whooping coughwhooping cough

Laboratory diagnosisLaboratory diagnosis

SpecimenSpecimen::Organisms in the post nasal spaceOrganisms in the post nasal space

may be obtained bymay be obtained by::11 - -Pernasal swab, nasal saline washPernasal swab, nasal saline wash..

22 - -Nasopharyngeal swabNasopharyngeal swab..33 - -A cough plate held infrontA cough plate held infront

of the mouthof the mouth..

CultureCulture::

- -Specimens are innoculated on Bordet Specimens are innoculated on Bordet Gengou plates, with and without Gengou plates, with and without

penicillinpenicillin 37°C 37°C , ,

3-73-7 days in a moist environmentdays in a moist environment..small bisected pearlysmall bisected pearly

colonies appearcolonies appear..

- -Colonies are identifiedColonies are identified

by: - Slide agglutinationby: - Slide agglutination..

- - IFIF..

Molecular techniquesMolecular techniques::

PCR: using B. pertussis primersPCR: using B. pertussis primers..

TreatmentTreatment:: - -In the catarrhal stage:In the catarrhal stage: erythromycin erythromycin

(prophylactic)(prophylactic).. - -In the paroxysmal stageIn the paroxysmal stage:: antibiotics cannot antibiotics cannot

change the course of illnesschange the course of illness . .

VaccinesVaccines::11 - -Merthiolate- killed B. pertussisMerthiolate- killed B. pertussis, usually , usually

combined with diphtheria and tetanus toxoids combined with diphtheria and tetanus toxoids (DPT). Given in 3 injections at monthly intervals (DPT). Given in 3 injections at monthly intervals starting at 2-3 months of agestarting at 2-3 months of age..

22 - -Acellular vaccinesAcellular vaccines containing 1-5 Ags, the more containing 1-5 Ags, the more the betterthe better..

ProphylaxisProphylaxis:: - -Erythromycin for 5 days for unimmunized infants or Erythromycin for 5 days for unimmunized infants or

exposed adultsexposed adults..