Bordetella pertussis – PCR

Diagnostic Use

Pertussis is caused by the gram-negative coccobacillus Bordetella pertussis, a strict human pathogen with no known animal or environmental reservoir. Pertussis is a highly contagious respiratory illness. In adolescents and adults, infection may result in a protracted cough and is occasionally associated with substantial morbidity. In children, and particularly infants, morbidity is more often substantial, and the disease may be fatal.

In the pre-vaccine era, the disease predominantly affected children <10 years of age and usually manifested as a prolonged cough illness with one or more of the classical symptoms: inspiratory whoop, paroxysmal cough, and post-tussive emesis. In adolescents and adults, symptoms and signs of pertussis are often nonspecific.

The organism is fastidious, surviving only a few hours in respiratory secretions and thus requiring special media for culture. When considering testing for Bordetella Pertussis, PCR is the test of choice during the acute stages of pertussis infection, up to 4 weeks after the onset of symptoms.

**January 2025: NZ is currently experiencing high pertussis activity.
Pertussis PCR testing is only recommended for patients who meet the clinical criteria below.

They have an illness that is clinically compatible with pertussis
AND
It is within 3 weeks of cough onset
AND
Any one of the following applies to the person:
* they are aged under 5 years
* they are pregnant and in the third trimester
* they have a chronic respiratory condition and/or are immunocompromised
* they have been admitted to hospital
* they live, work, or routinely spend time with a child/children aged under 12 months, pregnant people, or other people at risk of severe outcomes
* there has been a specific request from the Medical Officer of Health to test

Patients who fall outside of these criteria, but for whom laboratory confirmation is still thought to be clinically justified, should be discussed with the on-call clinical microbiologist in the first instance.

Symptomatic contacts of laboratory confirmed cases fulfil the case definition of pertussis (via an epidemiological link) and should NOT have a test done unless requested by public health.

Clinical details as specified above must be provided or specimens will be rejected.

Please refer to Te Whatu Ora testing guidance in the Additional Information section below.

Department

Microbiology - Virology

Delphic Registration Code

BPCR

Laboratory Handling

Laboratory

Testing is batched daily on routine weekdays at approximately 9.30am, with results available from mid-afternoon. Urgent or weekend testing must be discussed with and approved by a Microbiologist.

Test Adds

Add-ons can be made if an appropriate sample has already been received for other PCR testing. Please call Virology to discuss.

Synonyms

PCR - Bordetella pertussis
PCR - Whooping cough
Pertussis - PCR
Whooping cough - PCR

Turnaround Time

3 days

Test Code

2532

Specimen Type

• Nasopharyngeal Swab
• Aspirate

Specimen Requirements

Tube/Container Type:

Preferred

• Swab - Viral

Acceptable

• Pottle

Additional Specimen Information

Preferred specimen is a Nasopharyngeal or pernasal swab in VTM however is a dry swab is also an acceptable specimen (please leave dry swabs in their original containers).

Swab packs (Respiratory/Covid packs) can be requested by emailing LabInfo@cdhb.health.nz

After processing, samples are stored frozen for 4 weeks before discard. Add-on requests can be made for other appropriate tests during this time frame by contacting Virology.

Testing is performed daily on routine weekdays.

Please see link to Swab Guide under Additional Information section below

Aliquot Instructions

Transport to Lab

Chilled (2 - 8 degrees Celsius)

Interpretation

PCR offers a highly sensitive and specific technique for diagnostic testing and allows for same day results. PCR is more sensitive than and remains positive longer than culture. PCR is more likely than culture to detect infection in individuals treated with antibiotics.

1. Clinical pertussis infection in an unimmunised individual has an incubation period of 7 – 10 days (range 6 – 20 days).

2. The first symptomatic or catarrhal stage exhibits non-specific symptoms consistent with many different upper respiratory tract infections (URTI) and it is difficult to clinically distinguish infection from other causes of URTIs. During this stage the organisms is highly communicable and most readily isolated from the posterior nasopharynx. Antibiotics can be effective at modifying the course of disease at this stage.

3. The paroxysmal phase follows the catarrhal stage and exhibits a dry non-productive cough culminating in a whoop with or without vomiting. This may persist for up to 4 weeks. There is a decrease in the number of bacteria, and antibiotics will have little or no effect at modifying the disease at this stage.

4. Complications can include otitis media, pneumonia, toxic nervous system manifestations and pneumothorax.

5. Bordetella pertussis is a fastidious organism requiring specialised growth conditions, and bacterial isolation is also reduced with an advancing disease state. DNA detection by PCR detects Bordetella pertussis with increased sensitivity and over a longer period of the disease compared to culture.

6. The PCR is able to detect one CFU (Colony Forming Unit) / millilitre. Sensitivity is increased if sampling is performed before 10 days of symptoms has elapsed

Positive results are Notifiable to the Medical Officer of Health.

Urgent testing by arrangement, please call a CHL Microbiologist to discuss.

Test Method

Bordetella pertussis and Bordetella parapertussis DNA detection. Nucleic acid extraction, PCR amplification and detection.
Bordetella holmesii can be tested for if indicated.

Non-Funded Test Cost

$111.11 (Exclusive of GST)

Billing Code

2532

Resources

• Nasopharyngeal Swab Collection
• Swab Guide
• Te Whatu Ora Pertussis Testing Guidelines (161 KB)

Contact Information

Enquiry Form

Contact Information

Enquiry Form