Table 2.

MTBDRsl Performance on Smear-Negative Sputa at Ramp Rates of 2.2°C/second (Manufacturer-Recommended) or 4.0°C/second (52 Isolates)

Ramp rate (°C/second)	TUB-band–positive	TUB-band–positive
		Indeterminate for any gene locus	Incorrect banding call	Incorrect drug class diagnostic call	Valid result
2.2	52/52∗ (100)	0/52† (0)	0/1300‡ (0)	0/104§ (0)	52/52† (100)
4.0	51/52∗ (98), P = 0.315	7/51† (14), P = 0.006	54/1275¶ (4), P < 0.001	6/102‖ (6), P = 0.013	41/51† (80), P = 0.001

Data are expressed as n/N (%). Accuracy for Mycobacterium tuberculosis–complex-DNA, and then further analysis of indeterminate rates, incorrect banding calls, and incorrect drug class diagnostic calls were done. The number of valid results [52 of 52 (100%) versus 41 of 51 (80%)] improved by 21% (95% CI, 8–34; P < 0.001). P values are for within-column comparisons between different ramp rates. Significant P values are marked in bold. Incorrect banding call, the presence or absence of a band deviating from the true banding call; Incorrect drug class diagnostic call, the presence or absence of banding patterns resulting in deviation of the true susceptibility to a drug class; Indeterminate, one or more gene locus control is absent; MTBDRsl, GenoType MTBDRsl VER 2.0; TB, tuberculosis; TUB-band–positive, positive for Mycobacterium tuberculosis–complex-DNA; Valid result, TUB-band–positive, determinate for all gene locus controls, thus having diagnostic calls for both drug classes.

^∗Total number of clinical specimens.

^†TUB-positive strips.

^‡Fifty-two TUB-band–positive strips × 25 bands per strip.

^§Fifty-two TUB-band–positive strips × 2 drug class diagnostic calls.

^¶Fifty-one TUB-band–positive strips × 25 bands per strip.

^‖Fifty-one TUB-band–positive strips × 2 drug class diagnostic calls.