TABLE 1.

Spiking of CSF with viable M. tuberculosis complex isolate of known CFU number

M. tuberculosis complex isolate (IS6110 copy no.)	CFU in 10 μl of extract	No. of IS6110 copies	No. positive (%) by IS6110 PCR (n = 3)a
M. tuberculosis (17)	400	6,800	3 (100)
	40	680	3 (100)
	4	68	3 (100)
M. tuberculosis (1)	50	50	3 (100)
	5	5	3 (100)
	0.5	0.5	1 (33.3)
BCG (1)	1000	1000	3 (100)
	100	100	2 (66.6)
	10	10	0 (0)

^aThat is, the number of three replicates found to be positive by IS6110 PCR.