Genus Bordetella

Prof. V. JayapalMicrobiology department

MGMC & RI

Whooping coughPertussis means --------“violent cough,”

The inspiratory sound made at the end of an episode of paroxysmal coughing gives rise to the common name for the illness, “whooping cough.”

However, this feature is variable: it is uncommon among infants ≤6 months of age and is frequently absent in older children and adults.

The Chinese name for pertussis is “the 100-day cough,” which accurately describes the clinical course of the illness.

Whooping cough

• Pertussis remains an important cause of infant morbidity and death.

• Pertussis vaccination in the past years has reduced the incidence of pertussis.

• A disease of childhood, • But can affect people of all ages and is

increasingly being identified as a cause of prolonged coughing illness in adolescents and adults.

Whooping cough

A highly communicable disease.Worldwide distribution .Attack rates: • 80–100% among unimmunized household contacts • 20% within households in well-immunized

populations.

Genus BordetellaSpecies Disease caused RemarksB. pertussis Whooping cough in

humanMost important species causing human disease

B.parapertussis Whooping cough in human

Cause Mild illness in human

B.bronchiseptica Occasionally infects human(condition resembling whooping cough in human)

B.avium Respiratory disease in Turkeys

B.pertussisMorphology of the bacteria

A small , ovoid, coccobacilliGram negativeNon-motile, non-sporing CapsulatedBipolar metachromatic granules ( demonstrated

by staining with toludine blue)

B.pertussis( Gram’s stain)

B.pertussisCultural characters

• An obligate aerobe• Grows best at 35-37oC.• Medium used for isolation from clinical

samples: 1) Bordet-Gengou glycerine –potato-blood

agar. 2) Regan-Lowe medium 3) Charcoal blood agar medium.

B.pertussisCultural characters (Continued)

• Grow slowly• Incubation– 48 to 72 hours• Colony– Small, dome-shaped, grayish white,

refractile and glistening – Resemble “ mercury drops / bisected pearls”.

• Hazy zone of hemolysis around colonies present.• Confluent growth—Gives an” aluminium paint “

appearance.

B.pertussis-colony morphology

B.PertussisBiochemical reactions

Biochemically inactiveDoes not ferment sugars, ‘ ‘ form indole , , reduce nitrates , , utilize citrate , , split urea

Produces oxidase and catalase.

B.pertussisResistance

• Killed by heat at 55oC in 30 minutes• On dried droplets survive for few days.

B.pertussisVirulence factors

1.Pertussis toxin2.Agglutinogens3.Filamentous hemagglutinin4.Peractin5.Lipopolysaccharide (LPS)

B.pertussis1.Pertussis toxin

• 117,000- Molecular weight• Composed of two units, A & B Unit B– Binding component Unit A– Active component of toxin. Toxin can be toxoided ( PT toxin is the

major component of acellular pertussis vaccine)

B.pertussis2.Filamentous hemagglutinin (FHA)

• FHA 1,2 and 3.• Antigenic• Antibodies induced against FHA are protective• An important component of acellular pertussis

vaccine

B.pertussis3.Peractin

• Outer membrane protein antigen (OMP).• Forms a part of acellular pertussis vaccine.

Pathogenicity

• An obligate human pathogen.• Incubation period- 1-2 weeks• Route of entry– Respiratory route• Disease is described in 3 stagesOnset of disease : insidious .

Three stages of whooping cough disease

Clinical stages

1. Catarrhal stage : Catarrhal symptoms, low grade fever, dry cough.

2. Paroxysmal stage : Cough comes in distinctive bouts. Experiences violent spasms of continuous coughing. Coughing is followed by a long- in-rush of air into the almost empty lungs, with a charecteristic whoop.

3. Convalescent stage : Frequency and severity of cough decreases.

Disease lasts for 6 -8 weeks.

Complications

1.Pressure effects of coughing: Subconjunctival hemorrhage Subcutaneous emphysema2. Respiratory: Bronchopneumonia. Lung

collapse3. Neurological : Convulsions and coma.

Can lead to epilepsy, paralysis, retardation, blindness, deafness.

Laboratory diagnosis

1. Collection and transport of respiratory samples: - Per nasal swab -Post nasal swab -Cough plate method ( Keep plate 10-15 cm from mouth)Swabs are transported in : Modified Stuart’s medium 2. Culture .i Bordet-gengou ii. Regan Lowe (contain antimicrobial to inhibit

growth of normal flora)

Laboratory diagnosis

3. Bacterial growth on plates is confirmed with Direct immunofluorescence using specific antiserum.

4. PCR5. Serological tests– Not much useful.

Treatment

• B.pertussis is susceptible to many antimicrobials:

Erythromycin, Co-trimaxazole

Prophylaxis ( triple vaccine)

Primary vaccination:Triple vaccine ( Tetanus, diphtheria, and

Whooping cough)– DPT vaccine

Booster vaccination :

Prophylaxis

1. Whole cell killed vaccine Diphtheria, pertussis, and tetanus toxoid (DPT- Triple

vaccine).

2. Acellular vaccine: has only 3 purified components of the Bordetella pertussis.---

i) Pertussis toxin ii)Filamentous hemagglutinins 1,2,3 (FHA) iii) PeractinLesser complications than whole-cell vaccine.

Vaccine for Whooping cough1. CDC recommends that infants and children get DTaP vaccine at 2

months, 4 months, 6 months, and 15 months.2.A booster of DTaP is given at 4 years of age.

3.Because protection from DTaP fades over time, CDC recommends another dose of whooping cough vaccine, known as Tdap, for adolescents (ideally at 11 or 12 years)

4. Women during each pregnancy (ideally in the third trimester).

5. Adults who have never received Tdap should get one dose now.

Tdap during pregnancy

• By getting Tdap during each pregnancy, mothers build antibodies that are transferred to the newborn, likely providing protection against pertussis in early life, before the baby can start getting DTaP vaccines at 2 months old.

Contacts of a whooping cough patient

• House hold contacts may need antimicrobial prophylaxis• Infants younger than 12 months old are most at risk for

serious complications from pertussis. • Although pregnant women are not at increased risk for

serious disease, those in their third trimester would be considered at increased risk since they could in turn expose their newborn to pertussis.

• You should discuss whether or not you need preventative antibiotics with your doctor, especially if there is an infant or pregnant woman in your household or you plan to have contact with an infant or pregnant woman.

Contacts of a person with whooping cough(Post exposure prophylaxis in infants)

• Infants more than 1 month of age: erythromycin, clarithromycin,

azithromycin.• Infants less than 1 month of age :

Azithromycin

Epidemiology

• B.pertussis- Responsible for 95% cases• B.parapertussis– for 5% cases• B.bronchiseptica- occasionally cause disease

• Pseudo whooping cough:======================• Syndrome resembling whooping cough.• By other respiratory pathogens ( adenovirus,

Mycoplasma pneumoniae)

Epidemiology

• Predominantly a pediatric disease.• Incidence and mortality high in the 1 st year of life.• Occurs workdwide.• Females more affected than males.• Source of infection : Infected person; droplet

transmission; fomites ( contaminated objects).• Also affects adolescents and adults.• Protection occurs after first attack. Yet, second

attacks have been reported.

Hygiene

• Like many respiratory illnesses, pertussis is spread by coughing and sneezing while in close contact with others, who then breathe in the pertussis bacteria. Practicing good hygiene is always recommended to prevent the spread of respiratory illnesses:

• Cover your mouth and nose with a tissue when you cough or sneeze.• Put your used tissue in the waste basket.• If you don't have a tissue, cough or sneeze into your upper sleeve or

elbow, not your hands.• Wash your hands often with soap and water for at least 20 seconds.• If soap and water are not available, use an alcohol-based hand rub.

Bordetella parapertussis

• Infrequent cause of whooping cough.• A milder diseaseDifference with B.pertussis: 1. B .parapertussis grows of Nutrient agar with

brown, diffusible pigment after 2 days.

B.bronchiseptica

• Occurs naturally in the respiratory tract of many animals.

• Very small proportion of whooping cough is caused by it.

• Antigenically related to B.pertussis.

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