Semiquantitative Polymerase Chain Reaction Enzyme Immunoassay for the Diagnosis of Pertussis

 The two most commonly used targets for diagnosis of pertussis by the polymerase chain reaction have been the pertussis toxin promoter and the repeated insertion sequence IS481. A comparative assessment of these primers was performed on routinely collected nasopharyngeal swabs, stored at –20  °C, using novel semiquantitative enzyme immunoassays. Both sets of primers behaved similarly with bacterial suspensions, and the 17 culture-positive nasopharyngeal swabs were also positive with the pertussis toxin promoter primers, with one exception, which had been subject to prolonged storage. Significantly more of the 69 culture-negative swabs were positive with the pertussis toxin promoter primers (n=36) than with the IS481 primers (n=18). To determine the effect of inhibitors, a comparative assessment of three primer pairs against human DNA (β-globin and glyceraldehyde-3-phosphate dehydrogenase) was also performed.