TRICORE, a novel bead-based specimen concentration method for the culturing of Mycobacterium tuberculosis.

Centrifugation is a necessary concentrating step for the detection of Mycobacterium tuberculosis in a liquid culture. However, centrifugation is biologically hazardous and presents an obstacle in the development of an automated culture system. A bead-based bacterial concentration method, TRICORE, was recently developed by Genetein Co., Ltd. We compared the efficacy of TRICORE and conventional centrifugation for concentrating M. tuberculosis in clinical sputum specimens by using liquid and solid culture systems. Among 90 pretreated clinical sputum specimens, 51 (57.3%) and 55 (61.8%) M. tuberculosis isolates were recovered by the MGIT culture system by using the centrifugation and TRICORE methods, respectively (chi-square test, p=0.5413). The detection time for the centrifugation method was 359.3±117.0 h, while that for the bead-based concentration method was 377.6±162.3 h (p=0.5637). However, the number of colonies recovered on solid media were significantly higher with the TRICORE method (p=0.003). In particular, among the smear-negative specimens, culture positivity of the TRICORE method was 39.6%, while that of the centrifugation method was 15.1%. The TRICORE bead-based concentration method was considered equivalent to centrifugation and enabled efficient collection of paucibacillary specimens in solution. Thus, the new noncentrifugation concentration method could yield more positive culture results.