Fig 2. Sample size and sensitivity.

A. M. bovis BCG was spiked at 10³ CFU/ml into 0.2, 0.5 and 1 g of stool (N = 4). Columns = pressure; lines = Cycle thresholds (Cts). B. Stool samples were collected from macaques infected with M. tuberculosis and three different amounts (0.2g, 0.6g and 1g) were tested. The number in parenthesis indicates number of macaques tested at each volume. The shades of gray on the graph indicate the number of times the test was performed on the same stool sample. Light gray = 1 test only; medium gray = combined data from 2 tests; dark gray = combined data from 3 tests. All the uninfected controls tested (N = 5) were negative by this method.