Table 1– Comparison of cerebrospinal fluid (CSF) protocols for Xpert MTB/RIF testing

Protocol	Mean PCR cycle
Direct testing of CSF
0.5 mL	1.9
1.0 mL	1.4
1.5 mL	Referent
2.0 mL	1.5
Sample reagent:sample ratio
1:1	1.8
2:1	0.1
3:1	0.2
CSF centrifuged
4 mL	0.6
8 mL	0.2
Replicates of referent sample^#	1.7

Data are presented as the threshold difference. ^#: direct testing of 1.5 mL CSF.