(29), except that we added the recommendation of performing PCR for the older age group and the late stage of disease, as PCR may in some cases be positive after more than 3 weeks of cough, albeit by detection of DNA of nonviable B. pertussis cells. In another study, two-component cluster analysis was applied to sera from patients suspected of having pertussis which had been submitted to a large routine diagnostic laboratory over a period of 6 years (230). However, it is not precisely known which degree of increase is characteristic of a specific immune response. As PCR may detect DNA of nonviable bacteria, positive PCR results may be obtained for 1 to 2 weeks longer than positive culture results. The first involved the (only) commercial IgG-Ptx ELISA, in which one dilution of reference serum and one dilution of test serum were used. However, for the CF assay, it was suggested that the finding of strong CF activity in a first (single) serum could be considered supportive for diagnosis: high CF titers induced by infection were shown to decrease again quite rapidly, and sera of individuals who had a history of whooping cough in the previous 2 to 30 years mostly contained low CF activity, with none containing strong CF activity (168). Frits R. Mooi, Ph.D., is currently retired. In addition to IS481, two other IS elements have been detected in B. holmesii strains: ISBho1 (previously designated bhoA [18]) and IS1001Bhii (18). All Rights Reserved. In several studies, IgA-Ptx was shown to be less sensitive than IgA-FHA (187, 198, 201, 202). However, antibodies induced by a preschool booster dose may reach higher levels or may persist longer. – Furthermore, cutoff values may be increased or decreased depending on the question addressed. Many studies have shown that due to the presence of multiple copies in the Bordetella genomes, PCRs targeting IS elements are highly sensitive. Furthermore, in children from whom sera had been obtained at ages 13 months and 6 years, ≥2-fold increases of IgGs against B. pertussis FHA and Prn in the absence of detectable IgG-Ptx occurred in 11/14 and 8/14 children, respectively (219). The sensitivity of culture compared to PCR ranges from 26% to 85% (93, 150, 265

The resulting ROC curve had an AUC of 0.993. – NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. Cluster I and cluster III B. parapertussis strains are exclusively isolated from ovines and humans and are designated B. parapertussis If the IgG-Ptx level is below the chosen cutoff, the diagnosis of pertussis can be neither confirmed nor denied, and a second serum obtained at least 2 weeks later and 4 to 6 weeks after the onset of disease (and 6 to 8 weeks after the onset of disease for very young immune-naive children) (168) should be investigated. A study of nasopharyngeal sampling of Streptococcus pneumoniae revealed higher bacterial loads by quantitative PCR (qPCR) when nylon flocked swabs were used than when Dacron swabs were used (39). The assay using reference line units had the lowest intra-assay coefficients of variation (CVs) (4 to 7% versus 6 to 31% for the others) and the lowest interassay CVs (12 to 14% versus 12 to 47% for the others), the assay using single-point reference line units was second best, and the assay using endpoint titer calculation resulted in the highest CVs. 164). The Global Pertussis Initiative (29) proposed the utilization of 3 different age-related case definitions for pertussis, with distinctive diagnostic criteria for the age categories of 0 to 3 months, 4 months to 9 years, and ≥10 years.

ELISAs based on antigens not present in acellular vaccines.The introduction of ACVs raised the possibility of distinguishing between vaccination and infection by using antigens not present in the vaccine. Among those was the only ELISA (from the CDC) in which one dilution of test samples was used (233). In the past, many publications lacked sufficient detail to allow the reader to appreciate the quality of the presented PCR assays. See this image and copyright information in PMC. Most contaminations are caused by post-PCR handling of samples, which is necessary with conventional PCR methods, and most notably in nested PCRs, which require opening of vials after the first PCR to initiate a second round of PCR. B. holmesii has acquired DNA from B. pertussis, which, among others, contains genes for iron acquisition (18). 84), real-time PCR (85

The specificities of IS481 and IS1001 PCRs have been studied widely by analysis of genetically related pathogens or pathogens that occupy the respiratory tract (102). Linearity is the range over which an increase in input DNA results in an increase of amplified product. The resulting diagnostic algorithm recommends culture and PCR for the first age group (0 to 3 months), irrespective of cough duration, and PCR for the age group of 4 months to 9 years with a cough duration of <3 weeks. In conclusion, measuring IgG antibodies to B. pertussis antigens gives the best results in terms of sensitivity for all age groups. Also, the prevalence of B. pertussis-specific IgA antibody in the population tends to increase with age (199, 200). We also recommend PCR to complement serology for older age groups and for later disease, as DNA may be present in some cases for up to 38 days after onset (269). Several commercial assays are also closed systems, and some can be used with direct clinical samples, thus reducing or nearly eliminating contamination risk. Since B. parapertussis does not produce Ptx, the presence of Ptx antibodies suggests a coinfection of B. parapertussis and B. pertussis. Enzyme-linked immunosorbent assay (ELISA).After establishment of B. pertussis as the etiologic agent of whooping cough by Bordet and Gengou in 1906 (165), for a period of circa 80 years the complement fixation (CF) assay and the bacterial agglutination (BA) assay were the tests most used for serodiagnosis of the disease (166