Comparison of polymerase chain reaction with culture and enzyme immunoassay for diagnosis of pertussis.

A polymerase chain reaction (PCR) assay amplifying a segment of a repeated gene element of Bordetella pertussis was compared with culture and enzyme immunoassay (EIA) for the diagnosis of pertussis. The PCR assay was specific for B. pertussis in tests with a panel of other bacteria and with an extensive collection of specimen material from healthy persons and children with respiratory infections other than pertussis. The PCR assay was used in the analysis of 117 nasopharyngeal swabs collected from children at an elementary school at which a pertussis outbreak occurred. Fifty-six (48%) of the 117 swabs were positive, including those for all six culture-positive cases. The PCR method was then applied to analyze another pertussis outbreak. Of 40 nasopharyngeal aspirates taken from 37 clinically susceptible pertussis patients and from three asymptomatic contacts, the PCR identified 18 (45%), including all 3 culture-positive and 5 (35%) of the 14 seropositive patients. The most consistent and reliable diagnosis by positive PCR result was observed with those patients experiencing symptoms within 1 to 6 weeks of sample collection. We conclude that PCR is a rapid, sensitive, and specific means of diagnosing pertussis, especially during the first weeks of disease. The assay can be performed with both nasopharyngeal swabs and aspirates.