Diagnosis of Bordetella Pertussis Infections by Polymerase Chain Reaction

ABSTRACT

PURPOSE: Pertussis, a respiratory tract infection caused by Bordetella pertussis, is an important cause of morbidity in children. But diagnosis of pertussis is often delayed because of late development of typical symptoms and difficulties in culture. There has been no bacteriologically confirmed case of B. pertussis infection in Korea. Lower respiratoy tract may be involved in pertussis. We performed the polymerase chain reaction(PCR) assay for B. pertussis from children with lower respiratory tract infections. METHODS: One hundred eighty nine nasopharyngeal aspirates were collected from children with lower respiratory tract infections during the period from November 1990 to February 1995. Three 24-mer primers derived from DNA sequences upstream of the structural genes for the porin proteins of Bordetella P1 is shared by all three species and P2 is specific for B. pertussis and P3 is specific for B. parapertussis and B. bronchiseptica. Amplifications resulted in 159-bp PCR products specific for B. pertussis and 121-bp PCR products specific for B. parapertussis and B. bronchiseptica. A confirmatory cleavage of 159-bp PCR products of B. pertussis by Hae III revealed two bands of 22 and 137 bp. RESULTS: B. pertussis specific PCR products were visualized in 6 patients during 1991 and 5 of these had received appropriate doses of the combined DPT vaccine. They had had cough over 2 weeks in all and high fever in 4. They had been diagnosed as viral pneumonia in 5 and bronchiolitis in 1, but viral cultures for respiratory syncytial virus, parainfluenza virus, influenza virus, adenovirus were negative. There was no PCR product compatible with B. parapertussis or B. bronchiseptica. CONCLUSIONS: PCR assay is effective in diagnosis of B. pertussis infections. We suggest that there was an epidemic of pertussis in 1991 despite high rate of pertussis vaccine coverage in Korea.