Table 4.

Comparison of Methods Used for Oral Swab Collection and Analysis in a Previous Study and the Current Study

Method	Study by Nicol et al [13] Using In-House PCR Assay	Current Study Using Xpert MTB/RIF Ultra Assaya
Swab type	GE Healthcare OmniSwabs or Puritan PurFlock swabs	Copan FLOQSwabs or Puritan PurFlock swabs
Swab storage buffer	500 µL of 0-mmol/L Tris, 50-mmol/L EDTA, 50-mmol/L sucrose, 100-mmol/L NaCl, 1% SDS	500 µL of 0.9% sterile saline
Storage period before testing (−80°C)	6 mo to 2 y	6 m to 3 y
DNA extraction	Qiagen QIAmp DNA mini kit	Cepheid proprietary
Volume of eluate used for PCR	Entire eluate (15 µL of resuspended ethanol-precipitated DNA)	Cepheid proprietary
DNA target sequences	IS6110	IS6110, IS1081, rpoB
Cycle threshold for positivity	<40	<37 (IS6110 or IS1081); <40 (rpoB)

Abbreviations: EDTA, ethylenediaminetetraacetic acid; NaCl, sodium chloride; PCR, polymerase chain reaction; SDS, sodium dodecyl sulfate.

^aSee reference [16] for details of Xpert MTB/RIF Ultra assay.