Laboratory Testing for Pertussis [Utilization Spotlight]
Since 2012, we have been publishing a Utilization Spotlight in every issue of the Communiqué. Each Spotlight offers a quick view of utilization management best practices in action. This Spotlight is from January 2015.
Bordetella pertussis is the highly contagious etiological agent of pertussis or whooping cough. Bordetella parapertussis causes a similar but generally less severe illness. Diagnosis of pertussis is based on having a high clinical index of suspicion for the infection, along with confirmation by laboratory testing.
Bordetella pertussis is the highly contagious etiological agent of pertussis or whooping cough. Bordetella parapertussis causes a similar but generally less severe illness. Diagnosis of pertussis is based on having a high clinical index of suspicion for the infection, along with confirmation by laboratory testing. Laboratory testing methods include nucleic acid amplification tests (eg, PCR), serology, culture, and direct fluorescent antibody (DFA) testing. DFA detects the presence of the organism on glass slides using specific antibody and fluorescence microscopy. Culture and DFA are limited by low sensitivity, rendering nucleic acid amplification and, in select circumstances, serology the tests of choice.
The Centers for Disease Control and Prevention recommends PCR testing for patients suspected of having acute pertussis. Mayo Medical Laboratories offers test BPRP / Bordetella pertussis and Bordetella parapertussis, Molecular Detection, PCR as the preferred diagnostic test.
A positive result indicates the presence of DNA from Bordetella pertussis or Bordetella parapertussis. In some cases, a patient may test positive for both organisms. Cross-reactivity with Bordetella holmesii and Bordetella bronchiseptica may occur with the Bordetella pertussis assay.
A negative result indicates the absence of detectable Bordetella pertussis and Bordetella parapertussis DNA in the specimen but does not negate the presence of organism or active or recent disease. This may occur due to inhibition of PCR, sequence variability underlying primers and/or probes, or the presence of Bordetella pertussis or Bordetella parapertussis in quantities below the limit of detection of the assay.
Bordetella pertussis DNA can be detected up to 4 weeks or longer (up to 8 weeks in experience at Mayo Clinic) after symptom onset. Those presenting at a later time may test negative by PCR; under such circumstances, testing for Bordetella pertussis antibody, IgG, in serum may be considered. Serology testing for Bordetella pertussis will not detect antibodies to Bordetella parapertussis and is only useful for those with more than 2 weeks of symptoms. Vaccination against Bordetella pertussis may cause falsely positive serology test results. Neither PCR nor serology should be used as a test of cure or to monitor response to treatment. ￼￼