Table 1

Comparison of positive B. pertussis patient specimens by real-time RT-PCR assays Average crossing threshold (Ct) values and standard deviations (SD) for each combination of PCR and conventional results are shown. Samples were selected based on results for DFA/culture IS481 HP PCR.

Result combination

IS481 HP Assay

IS481 MB Assay*

TPR Assay*


Positive/tested (%)

Average Ct of positives

SD of positives

Positive/tested (%)

Average Ct of positives

SD of positives

Positive/tested (%)

Average Ct of positives

SD of positives


DFA negative Culture negative Screen PCR (IS481HP) positive

28/28 (100.0)

35.7

3.9

26/28 (92.9)

40.4

3.2

15/28 (53.6)

40.1

2.1

DFA negative Culture positive Screen PCR (IS481HP) positive

17/17 (100.0)

31.6

5.4

17/17 (100.0)

36.5

5.7

15/17 (88.2)

37.7

5.0

DFA positive Culture positive Screen PCR (IS481HP) positive

21/21 (100.0)

24.9

3.8

21/21 (100.0)

30.1

3.9

21/21 (100.0)

32.3

3.4


*In cases where cycle results were >45, 45 was used to calculate average Ct values and SD. HP = hybridization probe, MB = molecular beacon, TPR = toxin promoter region, DFA = direct fluorescent antigen.

Knorr et al. BMC Infectious Diseases 2006 6:62   doi:10.1186/1471-2334-6-62

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