Evaluation of the MeltPro Myco Assay for the Identification of Non-Tuberculous Mycobacteria

Figures & data

Table 1 Comparison of MeltPro Myco Assay and GenoType Mycobacterium CM Assay

Species	MeltPro Myco Assay/ GenoType Mycobacterium CM				Positive Agreement (%, 95% CI)	Negative Agreement (%, 95% CI)	Agreement (%, 95% CI)	Kappa Value
	+/+	±	-/+	-/-
M. intracellulare	130	1	1	129	99.24 (95.80–99.87)	99.23 (95.77–99.86)	99.23 (97.25–99.79)	0.992
M. abscessus	37	2	0	222	100.00 (90.59–100.00)	99.11 (96.80–99.75)	99.23 (97.25–99.79)	0.996
M. kansasii	8	1	0	252	100.00 (67.56–100.00)	99.60 (97.80–99.93)	99.62 (97.86–99.93)	0.998
M. fortuitum	8	0	0	253	100.00 (67.56–100.00)	100.00 (98.50–100.00)	100.00 (98.55–100.00)	1.000
M. avium	4	0	0	257	100.00 (51.01–100.00)	100.00 (98.53–100.00)	100.00 (98.55–100.00)	1.000
M. gordonae	3	0	0	258	100.00 (43.85–100.00)	100.00 (98.53–100.00)	100.00 (98.55–100.00)	1.000
M. chelonae	1	0	2	258	33.33 (6.15–79.23)	100.00 (98.53–100.00)	99.23 (97.25–99.79)	0.996
M. scrofulaceum	2	0	0	259	100.00 (34.24–100.00)	100.00 (98.54–100.00)	100.00 (98.55–100.00)	1.000
Mixed infection	9	0	0	252	100.00 (70.08–100.00)	100.00 (98.50–100.00)	100.00 (98.55–100.00)	1.000
Mycobacterium spp.	6	0	0	255	100.00 (60.97–100.00)	100.00 (98.52–100.00)	100.00 (98.55–100.00)	1.000
MTBC	21	5	0	235	100.00 (84.54–100.00)	97.92 (95.22–99.11)	98.08 (95.59–99.18)	0.990
Positive	232	6	0	23	100.00 (98.37–100.00)	79.31 (61.61–90.15)	97.70 (95.08–98.94)	0.885

Notes: “+” means positive result for the species; “-” means negative result for the species.

Table 2 List of Discrepant Results and Validation with Sequencing

Samples	GenoType Mycobacterium CM	MeltPro Myco Assay	ITS Sequencing
FZ 048	Negative	MTBC	Negative
FZ 055	Negative	MTBC	MTBC
FZ 084	Negative	MTBC	MTBC
FZ 090	Negative	M. kansasii	M. kansasii
FZ 160	M. chelonae	M. abscessus	M. abscessus
FZ 174	M. intracellulare	MTBC	MTBC
FZ 177	Negative	M. intracellulare	Negative
FZ 190	M. chelonae	M. abscessus	M. abscessus
FZ 246	Negative	MTBC	Negative

Table 3 List of Mixed Infection Samples and Validation with MTBC Test Kit and Sequencing

Samples	GenoType Mycobacterium CM	MeltPro Myco Assay	Verification Method^a
FZ 011	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 012	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 025	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 040	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 047	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 052	Mixed infection	MTB-M. avium	MTB-M. avium
FZ 078	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 089	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare
FZ 272	Mixed infection	MTB-M. intracellulare	MTB-M. intracellulare

Notes: ^aMTBC was confirmed using the MTBC test kit (Zeesan Biotech, Xiamen, China) that targets the IS6110 gene, M. avium was confirmed with the sequencing of a specific IS901 gene, and M. intracellulare was confirmed with the sequencing of a specific DT1 gene.

Table 4 Summary of Mycobacterium Species Identification of 261 Strains

Species	Number	Proportion of All NTM (N=202)^a
M. intracellulare	130	64.36%
M. abscessus	39	19.31%
M. kansasii	9	4.46%
M. fortuitum	8	3.96%
M. avium	4	1.98%
M. gordonae	3	1.49%
M. scrofulaceum	2	0.99%
M. chelonae	1	0.50%
M. arupense	1	0.50%
M. peregrinum	1	0.50%
M. phocaicum	1	0.50%
M. sinense	1	0.50%
M. vanbaalenii	1	0.50%
M. dioxanotrophicus	1	0.50%
MTBC	24
Negative	26
MTBC-M. intracellulare	8
MTBC-M. avium	1

Notes: ^aThe mixed infection samples were not included in the total number of NTM.