Bordetella pertussis was first observed in 1900 by Bordet and Gengou in the sputum of an infant with whooping cough. It took them six years to develop Bordet-Gengou medium to successfully isolate and culture the bacterium. B. pertussis causes the highly contagious respiratory disease pertussis (whooping cough), especially in infants. It produces several virulence factors like pertussis toxin and tracheal cytotoxin that damage the respiratory epithelium and cause symptoms. Diagnosis involves culturing on Bordet-Gengou medium or PCR. Azithromycin treatment reduces symptoms but not the course of disease. Pertussis vaccination with acellular DTaP

1. BORDETELLA SPP.
Salam Khassaf
M.Sc. In microbiology

2. History
In 1900, Jules Bordet along with Octave Gengou
observed a small ovoid bacterium in the sputum of a
5-month old child suffering from pertussis, or
whooping cough.

3. History
 The bacterium was similar to the Haemophilus
influenza, but showed distinct morphological
characteristics, which led Bordet and Gengou to
consider it as a separate species.
 the organism was unable to be isolated and
cultivated on ordinary blood agar plates .
 Six years later, Bordet and Gengou succeeded in
making a special medium, called Bordet-Gengou
(BG) medium , which served as a key factor for
isolating the difficult pathogen.

4. Classification
The scientific classification of the
bacterium
 Kingdom Bacteria
 Phylum Proteobacteria
 Class Betproteobacteria
 Order Burkholderiales
 Family Alcaligenaceae
 Genus Bordetella

5. Bordetella Spp. Overview
 There are eight described species .
 The most important human pathogen is B. pertussis. B.
parapertussis can occasionally cause a pertussis-like
syndrome in humans.
 B. bronchiseptica and B. holmesii are rare human
pathogens.
 B. bronchiseptica is found in many animals and is the
cause of kennel cough in dogs.
 Other species include Bordetella hinzii and Bordetella
trematum which are rare causes of sepsis in humans.
 Bordetella avium causes respiratory disease in poultry

6. General characters
 Bordetella spp. are minute Gram negative
coccobacilli.
 Most species in the genus are strict aerobes, and
grow optimally at 35–37°C .
 Bordetella pertussis and B. parapertussis are
nonmotile.
 B. pertussis is the most fastidious and requires
special media (Bordet - Gengou agar ) for isolation
, while B. bronchiseptica grows on ordinary
laboratory media.
 B. pertussis and B. parapertussis are human

7. Whooping cough
 Whooping cough, also called pertussis, is a highly contagious
bacterial infection of the lungs and airways caused by
Bordetella pertussis, a bacteria that lives in the mouth, nose,
and throat.
 Many children who contract pertussis have coughing spells that
last four to eight weeks.
 The disease is most dangerous in infants and spreads easily
from person to person, mainly through droplets produced by
coughing or sneezing.
 The first symptoms generally appear 7–10 days after infection,
and include mild fever, runny nose, and cough, which in
typical cases gradually develops into a paroxysmal cough
followed by whooping (hence the common name of whooping

8. Clinical features of pertussis

9. Whooping cough Fast facts
 Pertussis can cause serious illness in people of all ages and
can even be life-threatening , especially in babies.
 Approximately half of babies less than 1 year old who get
pertussis need treatment in the hospital.
 The most effective way to prevent pertussis is through
vaccination with DTaP for babies and children and with Tdap
for preteens, teens, and adults.
 Vaccination of pregnant women with Tdap is especially
important to help protect babies.
 In 2012, the most recent peak year, CDC reported 48,277
cases of pertussis in the United States, but many more go
undiagnosed and unreported. This is the largest number of
cases reported in the United States since 1955 when public

10.  Infectious tracheobronchitis, commonly known as kennel
cough, is a canine respiratory infection caused by Bordetella
bronchiseptica and canine parainfluenza virus.
 These pathogens attack the cilia lining the respiratory tract
and cause inflammation of the upper airway. This leads to
irritation of the airways and a dry cough .
Kennel cough in Dogs

11. Pathogenesis
 B.pertussis produces a number of factors that are
involved in the pathogenesis of disease.
 Filamentous hemagglutinin and fimbriae mediate
adhesion to ciliated epithelial cells and are essential for
tracheal colonization.
 Pertussis toxin promotes lymphocytosis, sensitization
to histamine, and enhanced insulin secretion and has
adenosine diphosphate – ribosylating activity, with an
A/B structure and mechanism of action similar to that of
cholera toxin.
 The filamentous hemagglutinin and pertussis toxin
are secreted proteins and are found outside of the B

12. Pathogenesis
 The tracheal cytotoxin is a peptidoglycan fragment,
which appears in the extracellular fluid where the bacteria
are actively growing.
 This substance is not a classic bacterial exotoxin since it
is not composed of protein.
 The tracheal cytotoxin which is toxic for ciliated
respiratory epithelium and which will stop the ciliated cells
from beating.
 The toxin kills ciliated cells and causes their extrusion
from the mucosa.
 It also stimulates release of cytokine IL-1, and so causes
fever.
 There is also evidence to suggest that this cytopathology
is the result of tracheal cytotoxin's increasing production

13. Pathogenesis
 Adenylate cyclase toxin is a protein toxin that
penetrates the host cell, is activated by host cell
calmodulin, and increases intracellular CAMP massively.
The increase of CAMP, which is rather short-lived as in
contrast to the action of pertussis toxin, is associated
with the inhibition of phagocytic cell oxidative responses
and natural killer cell (NK) activity.
 The lipopolysaccharide in the cell wall may also be
important in causing damage to the epithelial cells of the
upper respiratory tract.
 It is remarkable that heat-labile toxin ( LPS ) , adenylate
cyclase toxin, tracheal cytotoxin, and LPS are formed by
the three Bordetella species, whereas pertussis toxin

14. Pathogenesis

15. Laboratory Diagnosis
 The organism can be isolated from nasopharyngeal swabs
taken during the paroxysmal stage.
 Modified Bordet-Gengou medium , charcoal-horseblood
agar (Regan-Lowe) or grown in supplement Stainer-
Scholte broth used for this purpose .
 Identification of the isolated organism can be made by
agglutination with specific antiserum or by fluorescent-
antibody staining. However, the organism grows very slowly in
culture, so direct fluorescent-antibody staining of the
nasopharyngeal specimens can be used for diagnosis.
 Polymerase chain reaction –based tests are highly specific
and sensitive and should be used if available.
 Isolation of the organism in patients with a prolonged cough is
often difficult.
 Serologic tests that detect antibody in the patient’s serum can
be used for diagnosis in those patients.

16. Charcoal-horse blood agar(Regan-
lowe )
Bordetella pertussis colonies on bordetella selective medium (charcoal horse blood agar
with cefalexin).
Colony morphology: small, shiny, round colonies, mercury-silver in color. The colonies
become whitish grey with age.
Cultivation 5 days, 35 °C in an aerobic atmosphere. It is important that plates remain
moist during incubation.

17. Growth & identification
characteristics
Gram stain : Gram negative coccobacilli or short
rods.
Incubation conditions :
- 35 C
- for 3 – 5 days
-Aerobic with increased humidity and/or in a sealed
plate
Key Biochemical reactions :-
Catalase : positive

18. Treatment
 Azithromycin is the drug of choice.
 Note that azithromycin reduces the number of
organisms in the throat and decreases the risk of
secondary complications but has little effect on the
course of the disease at the “prolonged cough” stage
because the toxins have already damaged the
respiratory mucosa.
 Supportive care (e.g., oxygen therapy and suction of
mucus) during the paroxysmal stage is important,
especially in infants.

19. Prevention
 There are two types of vaccines: an acellular vaccine (DTaP)
containing purified proteins from the organism and a killed vaccine
containing inactivated B. pertussis Organisms
 The main immunogen in acellular vaccine is inactivated pertussis
toxin (pertussis toxoid). The acellular vaccine has fewer side effects
than the killed vaccine but has a shorter duration of immunity.
 The pertussis vaccine is usually given combined with diphtheria and
tetanus toxoids (DTaP) in three doses beginning at 2 months of age.
A booster at 12 to 15 months of age and another at the time of
entering school are recommended.
 To protect newborns, pregnant women should receive pertussis
vaccine.
 The killed vaccine is no longer used nowdays because it is suspected
of causing various side effects, including postvaccine encephalopathy
at a rate of about one case per million doses administered.
 The killed vaccine is still in use in some countries.