P03

Tuberculosis remains the leading infectious disease globally, with an estimated 10 million people developing the disease annually and a quarter of the world’s population being infected. The Central Tuberculosis Laboratory often receives requests for TB PCR of histological samples when specimen collection for TB cultures are omitted during the surgical procedure. We have previously validated the batch-based BD ProbeTec DTB and BD Max MDR-TB assays for the detection of MTB DNA in deparaffinised samples. To determine the suitability of Ultra as a stat test, archived residual deparaffinised samples (n=50) from the two assays were tested with the Ultra. The patients’ clinical information and culture results of alternative specimens were used to arbitrate non-concordant results. The overall concordance with the DTB and BD Max was 68.2% and 85.7% respectively. For the DTB samples (12 positive, 10 negative), the Ultra showed a specificity of 100% and a sensitivity of 41.7%. The storage age may have affected the DNA quality, and assay differences may have resulted in the low sensitivity as the Ultra showed a better performance for the BD Max samples (14 positive, 14 negative) with a specificity of 92.9% and a sensitivity of 78.6%. Most of the BD Max samples were low positives (n=11); the Ultra showed good correlation of the IS6110/IS1081 Ct values against that of the BD Max for the 3 samples with moderate DNA load. The Ultra provided rapid results within 75 minutes without any error messages and the categorical nature of results was also a useful advantage.