Background: Capilia TB is a simple immunochromatographic assay based on the detection of MPB64 antigen\r\nspecifically secreted by the Mycobacterium tuberculosis complex (MTC). Capilia TB was evaluated for rapid identification\r\nof MTC from BACTEC MGIT 960 and BACTEC 9120 systems in Kampala, Uganda. Since most studies have mainly dealt\r\nwith respiratory samples, the performance of Capilia TB on blood culture samples was also evaluated.\r\nMethods: One thousand samples from pulmonary and disseminated tuberculosis (TB) suspects admitted to the JCRC\r\nclinic and the TB wards at Old Mulago hospital in Kampala, Uganda, were cultured in automated BACTEC MGIT 960 and\r\nBACTEC 9120 blood culture systems. BACTEC-positive samples were screened for purity by sub-culturing on blood agar\r\nplates. Two hundred and fifty three (253) samples with Acid fast bacilli (AFB, 174 BACTEC MGIT 960 and 79 BACTEC\r\n9120 blood cultures) were analyzed for presence of MTC using Capilia TB and in-house PCR assays.\r\nResults: The overall Sensitivity, Specificity, Positive and Negative Predictive values, and Kappa statistic for Capilia TB\r\nassay for identification of MTC were 98.4%, 97.6%, 97.7%, 98.4% and 0.96, respectively. Initially, the performance of\r\nin-house PCR on BACTEC 9120 blood cultures was poor (Sensitivity, Specificity, PPV, NPV and Kappa statistic of\r\n100%, 29.3%,7%, 100% and 0.04, respectively) but improved upon sub-culturing on solid medium (Middlebrook\r\n7H10) to 100%, 95.6%, 98.2%, 100% and 0.98, respectively. In contrast, the Sensitivity and Specificity of Capilia TB\r\nassay was 98.4% and 97.9%, respectively, both with BACTEC blood cultures and Middlebrook 7H10 cultured\r\nsamples, revealing that Capilia was better than in-house PCR for identification of MTC in blood cultures.\r\nAdditionally, Capilia TB was cheaper than in-house PCR for individual samples ($2.03 vs. $12.59, respectively), and\r\nwas easier to perform with a shorter turnaround time (20 min vs. 480 min, respectively).\r\nConclusion: Capilia TB assay is faster and cheaper than in-house PCR for rapid identification of MTC from BACTEC\r\nMGIT 960 and BACTEC 9120 culture systems in real-time testing of AFB positive cultures.
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