Evaluation of the GenoType MTBDRplus and MTBDRsl for the detection of drug-resistant Mycobacterium tuberculosis on isolates from Beijing, China

Figures & data

Table 1 Phenotypic DST profiles of 96 isolates

Drug resistance	No. of isolates (%)
MDR-TB	66 (68.8)
XDR-TB	12 (12.5)
Any resistance to
RFP	78 (81.3)
INH	78 (81.3)
LFX	39 (40.6)
AM	11 (11.5)
CPM	18 (18.8)
EMB	40 (41.7)

Abbreviations: DST, drug susceptibility testing; MDR-TB, multidrug-resistant TB; XDR-TB, extensively drug-resistant TB; RFP, rifampicin; INH, isoniazid; LFX, levofloxacin; AM, amikacin; CPM, capreomycin; EMB, ethambutol.

Table 2 Performance of GenoType MTBDRplus and GenoType MTBDRsl assay compared to phenotypic DST

Genotypic DST results (n=96)	Phenotypic DST results		% Sensitivity (95% CI)	% Specificity (95% CI)	% PPV (95% CI)	% NPV (95% CI)	Diagnostic efficacy (%)	κ-value
	Resistant	sensitive
RFP
Resistant	77	2	98.7 (96.2-100)	88.9 (72.8-100)	97.5 (93.9-100)	94.1 (81.6-100)	96.9	0.895
sensitive	1	16
INH
Resistant	64	1	82.1 (73.3-90.8)	94.4 (82.7-100)	98.5 (95.4-100)	54.8 (36.3-73.4)	84.4	0.599
sensitive	14	17
MDR-TB
Resistant	63	0	80.8 (71.8-89.7)	100 (100-100)	100 (100-100)	54.5 (36.6-72.5)	84.4	0.612
sensitive	15	18
LFX
Resistant	35	2	89.7 (79.8-99.7)	96.5 (91.6-100)	94.6 (87.0-100)	93.2 (86.6-99.8)	93.8	0.869
sensitive	4	55
AM-CPM
Resistant	12	1	60.0 (36.5-83.5)	98.7 (96.1-100)	92.3 (75.5-100)	90.4 (83.9-96.8)	90.6	0.674
sensitive	8	75
EMB
Resistantsensitive	23	1	57.5 (41.5-73.5)	98.2 (94.6-100)	95.8 (87.2-100)	76.4 (66.3-86.4)	81.2	0.591
sensitive	17	55
XDR-TB
Resistantsensitive	6	2	50.0 (16.8-83.2)	97.6 (94.3-100)	75.0 (36.3-100)	93.2 (87.8-98.6)	91.7	0.556
sensitive	6	82

Note: AM/CPM indicates phenotypic resistance to amikacin and/or capreomycin.

Abbreviations: DST, drug susceptibility testing; PPV, positive predictive value; NPV, negative predictive value; RFP, rifampicin; INH, isoniazid; MDR-TB, multidrug-resistant TB; LFX, levofloxacin; AM, amikacin; CPM, capreomycin; EMB, ethambutol; XDR-TB, extensively drug-resistant TB.

Table 3 Variety of drug resistance patterns using GenoType MTBDRplus and MTBDRsl assay

Drug resistance patterns				Mutations detected	No. (%) of strains
RFP resistance pattern (rpoBgene)
WT probes		Mutant probes
ΔWT8		MUT3		S531L	46 (58.2)
ΔWT8		-		Unknown	5 (6.3)
ΔWT7		MUT2A		H526Y	7 (8.9)
ΔWT7		MUT2B		H526D	3 (3.8)
ΔWT7		-		Unknown	7 (8.9)
ΔWT3+ΔWT4		MUTI		D516V	8 (10.1)
ΔWT3+ΔWT4		-		Unknown	2 (2.5)
ΔWT2+ΔWT3		-		Unknown	1 (1.3)
INH resistance pattern
katG		inhA
WT probes	Mutant probes	WT probes	Mutant probes
ΔWT	MUTI	WT	-	S315T1	44 (67.7)
ΔWT	MUT1	ΔWTI	MUTI	S315T1+C15T	3 (4.6)
ΔWT	MUT1	ΔWT2	MUT3A	S315T1+T8C	1 (1.5)
ΔWT	MUT2	WT	-	S315T2	1 (1.5)
ΔWT	-	WT	-	Unknown	3 (4.6)
WT	-	ΔWT1	MUTI	C15T	13 (20.0)
LFX resistance pattern (gyrAgene)
WT probes		Mutant probes
ΔWT2		MUTI		A90V	10 (27.0)
ΔWT2		MUT2		S91P	5 (13.5)
ΔWT3		MUT3C		D94G	9 (24.3)
ΔWT3		MUT3A		D94A	3 (8.1)
ΔWT3		MUT3D		D94H	1 (2.7)
ΔWT3		MUT3A+MUT3C		D94A+D94G	2 (5.4)
WT		MUT3A		D94A	2 (5.4)
WT		MUT3B		D94N/D94Y	1 (2.7)
WT		MUT3c		D94G	1 (2.7)
WT		MUTI +MUT3c		A90V+D94G	2 (5.4)
WT		MUTI +MUT3A		A90V+D94A	1 (2.7)
AM/CPM resistance pattern (rrsgene)
WT probes		Mutant probes
ΔWT1		MUTI		A1401G	12 (92.3)
ΔWT2		-		Unknown	1 (7.7)
EMB resistance pattern (embB gene)
WT probes		Mutant probes
ΔWTI		MUTIB		M306V	13 (54.2)
ΔWTI		MUTIA		M306I	8 (33.3)
WT		MUTIB		M306VM3061	2 (8.3)
ΔWTI		-		1 (4.2)

Abbreviations: WT, wild-type pattern with all respective bands visible; ΔWT, lack of hybridization to the wild-type probe; MUT, mutation; RFP, rifampicin; INH, isoniazid; LFX, levofloxacin; AM, amikacin; CPM, capreomycin; EMB, ethambutol.