linear over 6 logs (dilutions 10 Ϫ2 through 10 Ϫ7 ). The IC was consistently detected in dilutions 10 Ϫ6 through 10 Ϫ9 . To determine interassay variation, we assayed 7 clinical samples positive for B. pertussis DNA within the linearity range of the assay 5 times on 5 different days (including reextraction each day). The SD calculated from the crossing points obtained was 0.08 -1.09. We determined intraassay variation by assaying 3 B. pertussis-positive clinical samples within the linearity range of the assay 5 times within a single assay (including different extractions). Mean crossing points were calculated, and the SD was 0.14 -1.04. The mean melting peak was at 62°C (range, 61.5-62.5°C).When clinical samples were tested, 46 of 219 nasopharyngeal swabs were found to be positive for B. pertussis DNA, with melting points at the expected temperature. Sera were obtained 4 weeks later from all patients with positive results and tested with the Serion ELISA classic for B. pertussis IgA (Institut Virion\Serion GmbH). A positive IgA result was obtained for all sera from patients with a positive PCR result. The new homologous IC was consistently detected in all negative and in 10 (22%) of 46 positive clinical samples. Extraction of samples was completed within 2 h. After the centrifugation step, real-time PCR took another 55 min. No contamination was observed during the entire study.PCR amplification may fail because of interference from PCR inhibitors; therefore, ICs have been incorporated in molecular assays for detection of B. pertussis (10,13 ). The homologous IC used in this study was coextracted with the clinical samples and coamplified with the same primers used for the target DNA. This procedure ensures accurate control of the entire molecular assay and represents the state of the art for ICs. The B. pertussis-specific IC gave positive results for all negative samples throughout the whole study, indicating successful removal of potential inhibitors by the extraction method. Contrary to a recent study using an identical amplification protocol (13 ), the sensitivity of the assay in this study was not affected by introduction of the homologous IC. Sensitivity to strains other than B. pertussis may also not be affected by introduction of this IC. In 78% of positive samples, competitive inhibition prevented detection of the IC.In conclusion, the newly established assay includes all of the features required for molecular detection of B. pertussis in the routine diagnostic laboratory. This molecular assay is suitable for the routine diagnostic laboratory and allows rapid and safe diagnosis of B. pertussis. Through autoverification, a customized expert system within the Laboratory Information System (LIS), a computer performs the initial review and verification of test results based on a predetermined set of boundaries or rules, as established by the laboratory (1 ). A carefully designed system can be an important tool in addressing such crucial issues as medical errors, test turnaround time (TAT), shortages in perso...

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Cation-exchange chromatography gives falsely decreased values for glycosylated hemoglobins (GHbs) in patients with abnormal hemoglobins (Hbs) such as S, D, G, C, E, and O. This decrease is thought to be proportional to the percentage of abnormal Hb present. In the authors' study, cation-exchange column chromatographic GHb values on 84 nondiabetic patients heterozygous for Hb S, 28 AS diabetic patients, and 23 nondiabetic patients heterozygous for Hb C were calculated to account for the percentage of abnormal Hb, and the resulting values were compared with the GHb values obtained by high-performance liquid chromatography (HPLC). There existed a good correlation between the calculated GHb and the GHb obtained by HPLC (r = 0.92 for AS and r = 0.94 for AC). In patients with elevated Hb F, chromatographic GHb values are falsely high. In such cases, correction can be made by subtracting the Hb F value from the observed GHb. In laboratories where cation exchange chromatography is used, accurate determination of GHb can be made by adjusting observed values for portion of the abnormal Hb present.