Table 2.

Diagnostic Accuracy of Tongue Swabs Compared With Xpert Ultra and Microbiological Reference Standard

	Samples With Valid Paired Xpert and qPCR Results			Excluded qPCR
Category	Xpert (Sputum)	qPCR (Tongue Swab)	Percent Agreement (95% CI)	Invalid	Not Tested
Total enrolled = 397	378	378		13 (3.3%)	6 (1.5%)
Overall agreement (without trace)	375	370	98.7 (96.9–99.4)
Overall agreement (with trace)	378	371	98.2 (96.2–99.1)
Negative	262	259	98.9 (96.7–99.7)	10 (3.8%)	5 (1.2%)
Positive (excluding trace)	113	111	98.2 (93.8–99.7)	3 (2.7%)	0
Positive (including trace)	116	112	96.6 (91.5–98.7)	3 (2.7%)	1 (0.09)%
Xpert Ultra semiquantitative
Very low	5	3	60.0 (23.1–92.9)	1
Low	26	26	100.0 (86.7–100.0)
Medium	33	33	100.0 (89.8–100.0)	1
High	49	49	100.0 (92.6–100.0)	1
Trace	3	1	33.3 (1.3–69.9)		1

	Samples With Valid Paired MRS and qPCR Results			Excluded qPCR
Category	MRS (Sputum)	qPCR (Tongue Swab)	Percent Agreement (95% CI)	Invalid	Not Tested
Total with valid results and culture data	354	354		13 (3.3%)	6 (1.5%)
MRS-negative (culture negative)	233	231	99.1 (96.9–99.8)	8	2
MRS-positive (culture plus Xpert)	121	112	92.6 (86.5–96.0)	4	1
Total	354	343	96.9 (94.5–98.3)
Indeterminate	24			1	3
Pending culture results	0

	Number of Samples With Valid Matched MRS and Xpert Results
Category	MRS (Sputum)	qPCR (Tongue Swab)	Percent Agreement (95% CI)
Total with valid results and culture data	369	369
MRS-negative (culture negative)	243	242	99.6 (97.7–100.0)
MRS-positive (culture plus Xpert)	126	118	93.7 (88.0–96.7)
Total	369	360	97.6 (95.4–98.7)
Indeterminate	28
Pending culture results	0

Category	Culture Positive	Culture Negative	Indeterminate
Xpert Ultra trace	2	1	1

Abbreviations: CI, confidence interval; MRS, microbiological reference standard; qPCR, quantitative polymerase chain reaction.