Bordetella pertussis detection is referred to Mayo Medical Laboratories and performed by rapid polymerase chain reaction (PCR) methodology. The assay uses repetitive insertion sequence (IS481) found in B. pertussis and (IS001) found in B. parapertussis. The rapid PCR hybridization assay was designed to perform with real time detection of the products by fluorescence resonance energy transfer (FRET) technology. The PCR assay is extremely sensitive and very specific.
II. Clinical Significance:
Pertussis (whooping cough) is an infectious respiratory disease caused by Bordetella pertussis bacterium. Pertussis afflicts both unvaccinated children and previously vaccinated children and adults in whom immunity has decreased. (Bordetella parapertussis can cause similar symptoms.) Most patients present with prolonged (whoop) cough. Clinical diagnosis of pertussis is complicated in infants because the characteristic whoop cough is rarely seen.
One nasopharyngeal specimen collected on rayon or polyester (aluminum or plastic shaft) swab placed in modified AMIES CHARCOAL medium (STARSWAB nasopharyngeal transport swab with charcoal system; MML supply #T286); obtained from the laboratory. Alternate specimens can be nasopharyngeal aspirate/wash or a nasal aspirate/wash collected in a sterile container and transported to the lab immediately. The specimen type and time of collection greatly impact the ability to detect Bordetella pertussis. Optimal specimens are nasopharyngeal swab (or aspirate/wash) collected 7 to 14 days post onset of symptoms. PCR testing is very sensitive and care should be taken not to contaminate the specimen.
The following specimens inhibit PCR testing and will be rejected: calcium alginate swabs, swabs sent in gel medium, cotton tipped swabs, swabs submitted in Stuart’s or Armies medium without charcoal and swabs sent in viral or universal transport medium. Also, throat, nose or nasal specimens are not acceptable and will be rejected. Specimen source is required for processing.
Laboratory personnel are not responsible for collecting these specimens. This is a nurse or physician collected specimen. The specimen must be labeled with the patient’s name, date and time of collection, initials of the person who collected the specimen and source.
Pertussis swab provided by the Mayo Medical Laboratories (supply #T286). Store the swab at room temperature.
Warning: Do not use calcium alginate swabs. Calcium alginate swabs inhibit PCR.
V. Reagents: N.A.
VI. Standardization: N.A.
A. Make certain the patient has no anatomic abnormalities of the nose (deviated septum).
B. Using the sterile nasopharyngeal rayon or polyester swab, gently insert into each nare of patient until the posterior nasopharynx is reached. Rotate swab gently, repeat for the other nare.
C. Insert the swab into the charcoal medium, cap and transport to the laboratory immediately.
A. Verify that the transport swab is labeled with the patient’s name, date and time of collection, initials of the person who collected and the specimen source.
B. Send specimen to MML (refer to the “MayoAccess; Operate” procedure).
VIII. Limitations: N.A.
IX. Results Derivation: N.A.
X. Expected Result(s) and/or Critical Values:
Negative for Bordetella pertussis/parapertussis DNA
Positive smears and/or cultures are reported to the City Health Department (589-4181). Refer to the “Reportable Infectious Diseases” policy.
XI. Quality Control: N.A.
1. Mayo Medical Laboratories Test Catalog; www.mayomedicallaboratories.com.
i. 12-10-82 E. Steiner
ii. 9-4-85 C. Harms (Revised: B. avium added, collect duplicate specimens-one for DFA and a second for culture)
iii. November 1988 C. Backes (Revised: added suspect Bordetella pertussis organism now sent to the State Hygienic Lab on BG plate-not a slant)
iv. June 1990 D. Smothers (Revised: VII.E.a-c., XI.)
v. November 1992 C. Brylski, A. Behnke (Revised: referral to State Hygienic Lab for culture and DFA)
vi. September 1994 C. Sullivan (Revised: kit storage)
vii. August 2002 A. Fletcher (Revised: III.; IV.1,2,3,5.; VII.2.; IX. for PCR testing)
viii. May 2010 L. Dolphin (Revised for referral to MML)
Interim Review: June 2011 L. Watters (Revised: III.)