Multitarget PCR for diagnosis of pertussis and its clinical implications

PCR has greatly facilitated pertussis diagnosis due to the speed, sensitivity, and specificity of this assay compared to other detection methods. Various single-target PCR assays are currently utilized, but none is universally considered to be the "gold standard." Our aim was to assess the use of multitarget versus single-target PCR for the diagnosis of pertussis in clinical samples. PCR assays targeting insertion sequence IS481 (IS), pertussis toxin ptxA promoter region (PT), and outer membrane porin (PO), or recA (RA) were evaluated in respiratory specimens collected from 4,442 patients with suspected pertussis. The diagnosis of pertussis was confirmed in 309 (6.96%) patients by the 3-target IS-PT-PO/RA PCR versus 247 (5.56%) by the conventional single-target IS (P = 0.007). Compared to single-target IS, the three-target combination increased the proportion of positive specimens by 1.25-fold, and two-target combinations increased the proportion of positive specimens by 1.10- to 1.24-fold. In addition, nine cases of B. parapertussis infection were also confirmed by using the discriminative features of this multitarget PCR. Of the 89 culture-proven pertussis cases, 17 (19.1%) and 5 of the 16 patients (31.3%) admitted to intensive care unit would have been missed had only the single-target IS PCR been applied. Patients with mild disease (P = 0.004) and shorter hospitalization (P = 0.006) were less likely to have positive cultures. This consensus generating real-time PCR approach permits a sensitive detection, as well as an accurate species identification of the causative Bordetella pathogens for the timely management of patients.