1663. Do the eyes have it? Performance of molecular detection of tuberculosis on tissues, including those with no visible tissue
Session: Poster Abstract Session: Mycobacterial Infections
Saturday, October 5, 2013
Room: The Moscone Center: Poster Hall C
Posters
  • Do the eyes have it TB PCR McKew.pdf (364.5 kB)
  • Background:

    Little work has been done on the performance of tuberculosis PCR with respect to the quality of tissue specimens. Laboratories often receive liquid samples with no visible tissue for testing. The sensitivity of TB PCR on these specimens is unknown.

    Methods:

    Culture and PCR results from all tuberculosis-positive tissues from January 2011 to January 2013 were analysed, noting whether tissue was not visible in the specimen. The gold standard used to analyse diagnostic utility was a combined clinical, microbiological or histopathological diagnosis of tuberculosis, excluding those with current or previous treatment.

    Results: 65 patients had 81 positive samples; 69 by PCR and 43 by culture. Using the combined gold standard: 51 of 57 (89%) were positive by PCR, versus 43 of 61 (70%) by culture. 44 samples with “no visible tissue” were tested. 4 were PCR-positive and one equivocal; one of the five was culture-positive. Two samples with no visible tissue were false negatives, as another sample from the same site was TB-positive.

    Conclusion: Sensitivity of TB PCR is superior to culture on tissue specimens. Of the seven patients with no visible tissue and a final microbiological diagnosis of tuberculosis at the site, 4 of 7 had positive PCR tests, one equivocal and two negative. 4 (9% of all tests performed on samples without visible tissue) were not confirmed by another method, and would have been missed had the test not been performed, which indicates testing these samples has utility. The quality of the specimen does, however, deserve comment, as the two (5%) known false negatives are of concern.

    Genevieve Mckew, M.B., B.S.(Hons), Melbourne, Infectious Diseases and Microbiology, Concord Hospital, Concord, Australia

    Disclosures:

    G. Mckew, None

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