Rapid Detection of Ethambutol-Resistant Mycobacterium tuberculosis from Sputum by High-Resolution Melting Analysis in Beijing, China

Figures & data

Figure 1 The region of embB targeted by the probe of MeltPro TB assay.

Table 1 Demographic and Clinical Characteristics of Patients Enrolled in This Study

Characteristics^a	Patients Enrolled (n=222)
Age–years
Mean	46.7
Range	15~88
Male sex–no.(%)	165(74.3)
Residence–no.(%)
Rural	77(34.7)
Urban	145(65.3)
Treatment history–no.(%)
New cases	123(55.4)
Previously treated	99(44.6)
Comorbidity–no.(%)
Diabetes	60(27.0)
Cardiopathy	12(5.4)
Live disease	6(2.7)
COPD^a	3(1.4)
Resistance to:–no.(%)^b
RIF	68(30.6)
INH	83(37.4)
LFX	39(17.6)
AMK	16(7.2)
MDR	53(23.9)
XDR	11(5.0)

Abbreviations: ^aCOPD, chronic obstructive pulmonary disease; ^bRIF, rifampicin; INH, isoniazid; LFX, levofloxacin; AMK, amikacin; MDR, multidrug resistance; XDR, extensive drug resistance.

Figure 2 Enrollment of participants.

Table 2 Performance of MeltPro for Detecting Ethambutol Resistance

MeltPro	MGIT		Total	Sensitivity (%, 95% CI)	Specificity (%, 95% CI)	PPV (%) (%, 95% CI)	NPV (%) (%, 95% CI)	Kappa Value
	R	S
R	49	9	58	83.1(73.5–92.6)	93.9(90.2–97.6)	84.5(75.2–93.8)	94.5(91.0–98.0)	0.78
S	10	154	164
Total	59	163	222

Abbreviations: R, resistant; S, susceptible; PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval.

Table 3 Distribution of embB Mutations Stratified to MeltPro Assay

Tube	Probe	No. of Isolates	Percentage (%)
Tube A	A (FAM, embB 306)	45	77.6
	B (TET, embB 497)	7	12.1
Tube B	C (FAM, embB 368, 378, and 380)	0	0.0
	D (TET, emb 406)	6	10.3
Total		58	100.0

Table 4 Analysis on Discordant Results Between MeltPro and MGIT for EMB Resistance

Type	No. of Isolates	Sequencing Analysis of embB Locus
		Mutation	Amino Acid Substitution
MeltPro R/MGIT S (n=9)	7	ATG→ATA	Met306Ile
	1	ATG→GTG	Met306Val
	1	GGC→GAC	Gly406Asp
MeltPro S/MGIT R (n=10)	9	WT	–
	1	GAT→TAT	Asp328Tyr

Abbreviations: R, resistant; S, susceptible; WT, wild-type.