TABLE 3.

COMPARISON OF XPERT SEMIQUANTITATIVE RANGES AND AFB SMEAR RESULTS FOR PELLETED SAMPLES

		AFB Smear Grade*
Xpert result (TB Ct range)		Negative	Scanty	1+	2+	3+	Total
Very low (28 < Ct ≤ 38)	%	65.4	20.6	8.4	2.8	2.8	100
	n	70	22	9	3	3	107
Low (22 < Ct ≤ 28)	%	25.5	19.3	37	12.8	5.4	100
	n	62	47	90	31	13	243
Medium (16 < Ct ≤ 22)	%	4.4	1.8	21.9	22.7	49.1	100
	n	17	7	84	87	188	383
High (Ct ≤ 16)	%	1.9	0	3.2	4.4	90.5	100
	n	3	0	5	7	143	158

Definition of abbreviations: AFB = acid-fast bacilli; Ct = cycle-threshold; TB = tuberculosis.

^*Excludes tests with internal control Ct greater than 34 and tests from site B, which was found to be an outlier in comparisons of average Mycobacterium tuberculosis Cts per smear grade (Figure 6).