Comparative Evaluation of Initial and New Versions of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for Direct Detection of Mycobacterium tuberculosis in Respiratory and Nonrespiratory Specimens

DOI: 10.1128/JCM.36.3.684-689.1998

Article Figures & Data

Table 1.

Detection of M. tuberculosis complex in respiratory specimens by initial and new versions of AMTDT

Microscopy result	Test and result	No. of specimens with the following culture result:
Microscopy result	Test and result	Positive^a	Negative	Total
Positive	AMTDT 1
	Positive	48	0	48
	Negative	0	19^b	19
	Total	48	19	67
	AMTDT 2
	Positive	48	0	48
	Negative	0	19^b	19
	Total	48	19	67
Negative	AMTDT 1
	Positive	34	0	34
	Negative	13	296^c	309
	Total	47	296	343
	AMTDT 2
	Positive	42	0	42
	Negative	5	296^c	301
	Total	47	296	343
Total	AMTDT 1
	Positive	82	0	82
	Negative	13	315^d	328
	Total	95	315	410
	AMTDT 2
	Positive	90	0	90
	Negative	5	315^d	320
	Total	95	315	410

↵a Only data for specimens with culture-positive results for M. tuberculosis are included.
↵b Nineteen specimens were AMTDT negative and culture positive for NTM.
↵c Seven specimens were AMTDT negative and culture positive for NTM.
↵d Twenty-six specimens were AMTDT negative and culture positive for NTM.

Table 2.

Comparison of confirmed results for respiratory specimens by AMTDT 1 and AMTDT 2

Test and result	No. of specimens with the following confirmed result:			Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
Test and result	Positive	Negative	Total	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
AMTDT 1
Positive	82	0	82	83.0	100	100	96.0
Negative	13	315^a	328
Total	95	315	410
AMTDT 2
Positive	90	0	90	94.7	100	100	98.4
Negative	5	315^a	320
Total	95	315	410

Table 3.

Detection of M. tuberculosis complex in nonrespiratory specimens by initial and new versions of AMTDT

Microscopy result	Test and result	No. of specimens with the following culture result:
Microscopy result	Test and result	Positive^a	Negative	Total
Positive	AMTDT 1
	Positive	21	0	21
	Negative	0	3^b	3
	Total	21	3	24
	AMTDT 2
	Positive	21	0	21
	Negative	0	3^b	3
	Total	21	3	24
Negative	AMTDT 1
	Positive	36	0	36
	Negative	11	201^c	212
	Total	47	201	248
	AMTDT 2
	Positive	38	0	38
	Negative	9	201^c	210
	Total	47	201	248
Total	AMTDT 1
	Positive	57	0	57
	Negative	11	204^d	215
	Total	68	204	272
	AMTDT 2
	Positive	59	0	59
	Negative	9	204^d	213
	Total	68	204	272

↵a Only data for specimens with culture-positive results for M. tuberculosis are included.
↵b Three specimens were AMTDT negative and culture positive for NTM.
↵c Six specimens were AMTDT negative and culture positive for NTM.
↵d Nine specimens were AMTDT negative and culture positive for NTM.

Table 4.

Discrepant results obtained for nonrespiratory specimens^a

Type of specimen	No. of specimens	AMTDT 1 result	AMTDT 2 result	No. of specimens inhibiting amplification (test)
Urine	1	Pos.	Neg.	1 (AMTDT 2)
Urine	3	Neg.	Pos.
Urine	2	Neg.	Neg.
Lymph node	3	Pos.	Neg.	3 (AMTDT 2)
Lymph node	1	Neg.	Pos.
Lymph node	1	Neg.	Neg.
CSF	1	Neg.	Neg.
CSF	1	Neg.	Pos.
Ascitic fluid	1	Neg.	Pos.
Gastric aspirate	1	Neg.	Neg.

↵a All specimens were negative forM. tuberculosis by microscopy but positive for M. tuberculosis by culture. Neg., negative; Pos., positive.

Table 5.

Comparison of confirmed results for nonrespiratory specimens by AMTDT 1 and AMTDT 2

Test and result	No. of specimens with the following confirmed result:			Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
Test and result	Positive	Negative	Total	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)
AMTDT 1
Positive	57	0	57	83.0	100	100	94.0
Negative	11	204^a	215
Total	68	204	272
AMTDT 2
Positive	59	0	59	86.8	100	100	98.4
Negative	9	204^a	213
Total	68	204	272