Table 2.

Effects of smear positivity after decontamination, storage time of sputum, and sputum volume on the rate of recovery of M. tuberculosis^a

Predictor	Total no. of specimens	No. (%) of specimens positive by BacT/Alert 3D system	P value for BacT/Alert 3D system	No. (%) of specimens positive by L-J medium	P value for L-J medium	No. (%) of specimens positive by Gottsacker medium	P value for Gottsacker medium
Smear positivity score
Doubtful	5	3 (60.0)	<0.001	4 (80.0)	<0.001	1 (20.0)	<0.001
1+	24	11 (45.8)		8 (33.3)		7 (29.2)
2+	44	34 (77.3)		31 (70.5)		23 (52.3)
3+	89	73 (82.0)		74 (83.1)		68 (76.4)
4+	157	130 (82.8)		132 (84.1)		137 (87.3)
Storage time (days)
16–30	8	6 (75.0)	0.605	7 (87.5)	0.07	7 (87.5)	0.111
31–60	19	12 (63.2)		15 (78.9)		15 (78.9)
61–90	47	41 (87.2)		41 (87.2)		40 (85.1)
91–120	69	53 (76.8)		58 (84.1)		59 (85.5)
121–150	65	49 (75.4)		51 (78.5)		43 (66.2)
151–180	111	90 (81.1)		77 (69.4)		72 (64.9)
Sputum vol (ml)
<2	97	78 (80.4)	0.619	68 (70.1)	0.023	55 (56.7)	<0.001
2–5	222	173 (77.9)		181 (81.5)		181 (81.5)

^an = 319.