Evaluation of MGIT 960 System for the Second-Line Drugs Susceptibility Testing of Mycobacterium tuberculosis

Table 4

Drug susceptibility and genotypic characterization of isolates show discrepant results between L-J and Bactec MGIT 960.

Discordant isolates	Susceptibility at the following concentration (μg/mL)				KIT number	Genotypic characterization
MXF	0.25	0.5	1.0
𝑆/𝑅	𝑅	𝑅	𝑆		1176, 1503, 1574	gyrA, wt; gyrB, wt
	𝑅	𝑅	𝑅		1575^a
LEV	0.5	1.0	2.0
𝑅/𝑆	𝑅	𝑆	𝑆		2933^b	gyrA, wt; gyrB, wt
𝑆/𝑅	𝑅	𝑅	𝑆		1147, 1155, 4900
KM	1.25	2.5	5.0
𝑆/𝑅	𝑅	𝑅	𝑅		1562, 1565	rrs, wt
CPM	0.625	1.25	2.5	5.0
𝑅/𝑆	𝑅	𝑆	𝑆	𝑆	4831	rrs, wt; tlyA, wt
𝑆/𝑅	𝑅	𝑅	𝑅	𝑆	1168, 1182, 2809
ETH	1.25	2.5	5.0
𝑅/𝑆	𝑅	𝑆	𝑆		5189	ethA, ethR, inhA, wt
	𝑅	𝑅	𝑆		5298^c	ethA, S266R; ethR, inhA, wt
𝑆/𝑅	𝑅	𝑅	𝑅		2934	ethA, ethR, inhA, wt
PAS	0.5	1.0	2.0	4.0
𝑅/𝑆	𝑅	𝑆	𝑆	𝑆	4891
𝑆/𝑅	𝑅	𝑅	𝑅	𝑆	1201, 1212, 1214, 1573	Not done
	R	R	R	R	4537

aDetermined as a false-resistant result.
bTreatment period of drug in this patient was 17 months.
cDetermined as a false-susceptible result.