Whole blood Taqman PCR leads in confirming meningococcal disease

Meningococcal disease (MCD) can now be diagnosed more reliably, concludes a study of the impact of a modified Taqman PCR test on suspected cases in a clinical setting. The whole blood (WB)-Taqman test is the test for suspected MCD, the authors say, and it should be used routinely.

Tests by the WB-Taqman method disclosed 88% of positive cases in patients with suspected MCD whereas tests in previous years, by the serum (S)-Taqman method, on similar patients at the same hospital uncovered significantly less, only 47%. The diagnostic sensitivity for the WB-Taqman method was 87% and specificity 100%. Combining the results of other tests—the rapid latex antigen test and blood culture—with those from the WB-Taqman method increased the proportion of positive tests for each patient cohort to 94% for the WB-Taqman method and 72% for the S-Taqman method. No false positive results occurred in either cohort; false negative results dropped to 13% by the WB-Taqman method.

The study was performed in patients with possible/probable MCD seen at the Royal Liverpool Children’s Hospital, UK. One cohort of 192 patients was seen between January 2000 and March 2001, after the WB-Taqman method had been introduced, and the other cohort of 319 patients was seen between December 1997 and March 1999. The same protocols were used in both studies, and PCR was performed by the Meningococcal Reference Unit, Manchester, UK.

PCR is invaluable for confirming MCD, often a rapidly fatal disease whose clinical diagnosis can be tricky.