Correction to: Molecular characterization of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates identifies local transmission of infection in Kuwait, a country with a low incidence of TB and MDR-TB.

The original publication of this article [1] contained few erroneous paragraphs and errors in Table 1 and Table 2. The first four paragraphs are in the 'Results' section while the last four paragraphs are in the 'Discussion' section. The errors in Table 1 involve the number of isolates tested for pyrazinamide and pyrazinamide susceptible isolates, ethambutol-susceptible isolates with a mutation and number of resistant isolates with a mutation for streptomycin. The error in Table 2 involves wrong codon number for a mutation in isolate KM17-01 in Cluster XII for gidB gene. The updated informations have been indicated in bold and also refer corrected Tables 1 and 2.

Correction to: Eur J Med Res (2019) 24:38 10.1186/s40001-019-0397-2

The original publication of this article [1] contained few erroneous paragraphs and errors in Table 1 and Table 2. The first four paragraphs are in the ‘Results’ section while the last four paragraphs are in the ‘Discussion’ section. The errors in Table 1 involve the number of isolates tested for pyrazinamide and pyrazinamide susceptible isolates, ethambutol-susceptible isolates with a mutation and number of resistant isolates with a mutation for streptomycin. The error in Table 2 involves wrong codon number for a mutation in isolate KM17-01 in Cluster XII for gidB gene. The updated informations have been indicated in bold and also refer corrected Tables 1 and 2.

Table 1

Phenotypic resistance by MGIT 960 system to anti-TB drugs among 93 multidrug-resistant M. tuberculosis isolates and number of susceptible and resistant isolates with mutations in target genes for each drug

Anti-tuberculosis drug	No. of isolates tested	No. of susceptible isolates	No. of susceptible isolates with mutationa	No. of resistant isolates	No. (%) of resistant isolates with mutationa
Rifampicin	93	0	0	93	93 (100)
Isoniazid	93	0	0	93	92 (98.9)
Pyrazinamide	46	10	0	36	30 (83.3)
Ethambutol	93	52	39b	41	38 (92.7)
Streptomycin	93	34	0	59	51 (86.4)

aResistance conferring mutations were detected in rpoB for rifampicin, katG + inhA for isoniazid, pncA for pyrazinamide, embB for ethambutol, and rpsL + rrs for streptomycin

bM. tuberculosis isolates with embB mutations usually confer low level of resistance to ethambutol which are often missed by the MGIT 960 system [23, 28]

Table 2

Detailed clinical, demographic and molecular characteristics of 42 M. tuberculosis isolates in 16 (Cluster I to Cluster XVI) clusters

Cluster no.	Clinica specimen	Isolate no.	Year of isolation	Patient’s nationality	Spoligotyping data		Genetic alteration detected in
					SIT	Mtb family	rpoB	katG	inhA	pncA	embB	rpsL	rrs	gidB	rpsA
I	Sputum	KM06-153	2006	Indian	255	Beijing	TCG456TTG	ACG315ACC	WT	WT	ATG306GTG	AAG43AGG	WT	N. D.	N. D.
	CSF	KM09-22	2009	Indian	255	Beijing	TCG456TTG	ACG315ACC	WT	WT	ATG306GTG	AAG43AGG	WT	N. D.	N. D.
	Sputum	KM13-37	2013	Indian	1	Beijing	TCG456TTG	ACG315ACC	WT	WT	ATG306GTG	AAG43AGG	WT	N. D.	N. D.
	FNA	KM16-06	2016	Nepalese	1	Beijing	TCG456TTG	ACG315ACC	WT	WT	ATG306GTG	AAG43AGG	WT	N. D.	N. D.
	FNA	KM17-03	2017	Indian	1	Beijing	TCG456TTG	ACG315ACC	WT	WT	ATG306GTG	AAG43AGG	WT	N. D.	N. D.
II	Sputum	KM14-58	2014	Nepalese	1	Beijing	TCG456TTG	ACG315ACC	WT	GTG139GCG	ATG306GTG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM14-69	2014	Indian	1	Beijing	TCG456TTG	ACG315ACC	WT	GTG139GCG	ATG306GTG	AAG43AGG	WT	GCA205GCG	WT
III	Sputum	KM08-501	2008	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	GGT139GTT	ATG306GTG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM08-502	2008	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	GGT139GTT	ATG306GTG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM09-207	2009	Indian	1	Beijing	TCG456TTG	ACG315ACC	WT	GGT139GTT	ATG306GTG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
IV	Sputum	KM12-05	2012	Ethiopian	21	CAS1-Kili	TCG456TTG	ACG315ACC	WT	Ins193A (FS) + TCC65TCT	ATG306GTG	AAG88AGG	WT	N. D.	N. D.
	Sputum	KM12-17	2012	Ethiopian	1144	T1	TCG456TTG	ACG315ACC	WT	Ins193A (FS) + TCC65TCT	ATG306GTG	AAG88AGG	WT	N. D.	N. D.
	Sputum	KM15-08	2015	Ethiopian	21	CAS1-Kili	TCG456TTG	ACG315ACC	WT	Ins193A (FS) + TCC65TCT	ATG306GTG	AAG88AGG	WT	N. D.	N. D.
V	Sputum	KM07-333	2007	Indonesian	Orphan	N. A.	TCG456TTG	ACG315ACC	WT	WT	WT	WT	WT	N. D.	N. D.
	Sputum	KM10-23	2010	Indian	355	EAI3-IND	TCG456TTG	ACG315ACC	WT	WT	WT	WT	WT	N. D.	N. D.
VI	Sputum	KM07-293	2007	Filipino	194	LAM2	TCG456TTG	ACG315ACC	WT	WT	CAG497CGG	WT	WT	N. D.	N. D.
	Sputum	KM12-01	2012	Filipino	25	CAS1-Delhi	TCG456TTG	ACG315ACC	WT	WT	CAG497CGG	WT	WT	N. D.	N. D.
VII	Sputum	KM09-202	2009	Ethiopian	47	H1	GTC176TTC	ACG315ACC	WT	WT	WT	WT	WT	N. D.	N. D.
	Sputum	KM15-17	2015	Indian	47	H1	GTC176TTC	ACG315ACC	WT	WT	WT	WT	WT	N. D.	N. D.
VIII	Sputum	KM14-67	2014	Ethiopian	149	T3-ETH	TCG456TTG	ACG315ACC	WT	− 11 A/G	ATG306ATC	WT	WT	GGT69GAT	WT
	Sputum	KM15-21	2015	Ethiopian	149	T3-ETH	TCG456TTG	ACG315ACC	WT	− 11 A/G	ATG306ATC	WT	WT	GGT69GAT	WT
IX	Sputum	KM07-283	2007	Indian	26	CAS1-Delhi	TCG456TTG	ACG315ACC	WT	TCC65TCT	ATG306ATA	WT	WT	N. D.	N. D.
	Sputum	KM14-68	2014	Indian	Orphan	N. A.	TCG456TTG	ACG315ACC	WT	TCC65TCT	ATG306ATA	WT	WT	N. D.	N. D.
	Sputum	KM17-20	2017	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	CAG497CGG	AAG43AGG	WT	GAA92GAC + GCA205GCG	WT
X	Sputum	KM17-22	2017	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	CAG497CGG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM17-73	2017	Indian	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	CAG497CGG	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Pus	KM11-503	2011	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM14-56	2014	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
XI	Sputum	KM15-13	2015	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM15-26	2015	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM17-02	2015	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
	Sputum	KM17-69	2017	Kuwaiti	1	Beijing	TCG456TTG	ACG315ACC	WT	− 11 A/G	GGC406GAC	AAG43AGG	WT	GAA92GAC + GCA205GCG	CGA212CGC
XII	Sputum	KM16-32	2016	Egyptian	19	EAI2-Manila	CAC451TAC	ACG315ACC	− 15 C/T	GAA37AAA	CTG355CTA + GAG378GCG	WT	WT	GTG110GTT + GCA205GCG	WT
	Sputum	KM17-01	2017	Filipino	19	EAI2-Manila	CAC451TAC	ACG315ACC	− 15 C/T	GAA37AAA	CTG355CTA + GAG378GCG	WT	WT	CTC59TTC + GTG110GTT + GCA205GCG	WT
XIII	Pus	KM07-297	2007	Indian	Orphan	N. A.	CAC451GAC	WT	− 15 C/T	TCC65TCG + Ins 453T (FS)	ATG306CTG	WT	WT	N. D.	N. D.
	FNA	KM11-502	2015	Indian	3361	T1	CAC451GAC	WT	− 15 C/T	TCC65TCG + Ins 453T (FS)	ATG306CTG	WT	WT	N. D.	N. D.
XIV	Sputum	KM06-48	2006	Egyptian	53	T1	TCG456TTG	WT	− 15 C/T	WT	WT	WT	WT	N. D.	N. D.
	Tissue	KM06-277	2006	Filipino	19	EAI2-Manila	TCG456TTG	WT	− 15 C/T	WT	WT	WT	WT	N. D.	N. D.
XV	Sputum	KM16-33	2016	Indian	8	EAI3/EAI5	CAC451TAC	ACG315ACC	WT	CTG35CCG	ATG306GTG + GAG378GCG	AAG43AGG	WT	GTG110GTT + GCA205GCG	WT
	Sputum	KM17-06	2017	Filipino	8	EAI3/EAI5	CAC451TAC	ACG315ACC	WT	CTG35CCG	ATG306GTG + GAG378GCG	AAG43AGG	WT	GTG110GTT + GCA205GCG	WT
XVI	Sputum	KM07-231	2007	Indian	Orphana	CAS1-Delhi	ATG440ATA + GAC441TAC	ACG315ACC	WT	TCC65TCT	GGC406TGC	WT	WT	GCA205GCG + Del 350G (FS)	WT
	Sputum	KM07-252	2007	Syrian	Orphana	CAS1-Delhi	ATG440ATA + GAC441TAC	ACG315ACC	WT	TCC65TCT	GGC406TGC	WT	WT	GCA205GCG + Del 350G (FS)	WT

Clusters containing MDR-TB strains with identical patterns and isolated within a period of nearly 2 years are shown as underlined. Synonymous mutations are italicized

N. A., not applicable; N. D., not done; CSF, cerebrospinal fluid; FNA, fine needle aspirate; SIT, shared international type; Mtb family, M. tuberculosis family; WT, wild-type sequence; Ins, insertion mutation; (FS), frame shift mutation, fine needle aspirate

aBoth isolates displayed identical spoligotyping pattern

Incorrect: Although all 93 MDR-TB isolates were tested for susceptibility to pyrazinamide, only 47 isolates yielded interpretable results; 11 isolates were susceptible and 36 were resistant to this drug including 15 isolates that were resistant to all five drugs. The remaining 46 MDR-TB strains failed to grow at the reduced pH in the absence of the drug.

Correct: Although all 93 MDR-TB isolates were tested for susceptibility to pyrazinamide, only 46 isolates yielded interpretable results; 10 isolates were susceptible and 36 were resistant to this drug including 15 isolates that were resistant to all five drugs. The remaining 47 MDR-TB strains failed to grow at the reduced pH in the absence of the drug.

Incorrect: The proportion of MDR-TB isolates exhibiting resistance conferring mutations in target genes varied for different anti-TB drugs, being highest for rifampicin and lowest for streptomycin (Table 1).

Correct: The proportion of MDR-TB isolates exhibiting resistance conferring mutations in target genes varied for different anti-TB drugs, being highest for rifampicin and lowest for streptomycin among SIRE drugs (Table 1).

Incorrect: PCR-sequencing of pncA identified mutations in 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 46 isolates for which phenotypic DST data for pyrazinamide was not available while all 11 isolates phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Correct: PCR-sequencing of pncA identified mutations in 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 47 isolates for which phenotypic DST data for pyrazinamide was not available while all 10 isolates phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Incorrect: Fifty isolates contained mutations at embB306 (M306V, n = 28; M306I, n = 19 and M306L, n = 3), 15 isolates contained a mutated embB406 (G406D, n = 8; G406A, n = 4; G406C, n = 2 and G406S, n = 1), 10 isolates contained a mutated embB497 (Q497R, n = 6; Q497K, n = 3 and Q497H, n = 1) and one isolate contained a mutation (Y319S) at embB319.

Correct: Fifty isolates contained mutations at embB306 (M306V, n = 28; M306I, n = 19 and M306L, n = 3), 16 isolates contained a mutated embB406 (G406D, n = 8; G406A, n = 5; G406C, n = 2 and G406S, n = 1), 10 isolates contained a mutated embB497 (Q497R, n = 6; Q497K, n = 3 and Q497H, n = 1) and one isolate contained a mutation (Y319S) at embB319.

Incorrect: Forty-nine of 59 MDR-TB strains additionally resistant to streptomycin contained a mutation in the target genes analysed (Table 1), many of which have been described previously [23, 28]. These included 44 isolates with a mutation in rpsL (K43R, n = 33; K43T, n = 1; K88R, n = 5; K88T, n = 4; K88M, n = 1), four isolates with a mutation in rrs 500 or 900 region (A514C, n = 1; C517T, n = 1; G878A, n = 1 and A906G, n = 1) and one isolate with rpsL K88R + rrs C602A double mutation.

Correct: Fifty-one of 59 MDR-TB strains additionally resistant to streptomycin contained a mutation in the target genes analysed (Table 1), many of which have been described previously [23, 28]. These included 44 isolates with a mutation in rpsL (K43R, n = 33; K43T, n = 1; K88R, n = 5; K88T, n = 4; K88M, n = 1), four isolates with a mutation in rrs 500 or 900 region (A514C, n = 1; C517T, n = 1; G878A, n = 1 and A906G, n = 1) and three isolates with double mutation inandgenes (K43R + C527T, n = 1;K88T + C517T, n = 1;K88R + C602A, n = 1).

Incorrect: Resistance conferring mutations in rpsL and/or rrs gene were detected in majority (49 of 59, 83%) of streptomycin-resistant but not in any streptomycin-susceptible MDR-TB strain while mutations in embB gene were detected in both ethambutol-resistant and -susceptible MDR-TB strains, as described in our previous studies [23, 28].

Correct: Resistance conferring mutations in rpsL and/or rrs gene were detected in majority (51 of 59, 86.4%) of streptomycin-resistant but not in any streptomycin-susceptible MDR-TB strain while mutations in embB gene were detected in both ethambutol-resistant and -susceptible MDR-TB strains, as described in our previous studies [23, 28].

Incorrect: Phenotypic DST results for pyrazinamide were available for only 47 of 93 MDR-TB strains while the remaining 46 isolates failed to grow at lower pH. No pncA mutation was detected in 50 pansusceptible strains. Analysis of 93 MDR-TB strains showed that 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 46 isolates for which DST data for pyrazinamide was not available contained a mutation in pncA while all 11 MDR-TB strains phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Correct: Phenotypic DST results for pyrazinamide were available for only 46 of 93 MDR-TB strains while the remaining 47 isolates failed to grow at lower pH. No pncA mutation was detected in 50 pansusceptible strains. Analysis of 93 MDR-TB strains showed that 30 of 36 MDR-TB strains phenotypically resistant to pyrazinamide and 23 of 47 isolates for which DST data for pyrazinamide was not available contained a mutation in pncA while all 10 MDR-TB strains phenotypically susceptible to pyrazinamide contained wild-type sequence for pncA.

Incorrect: The two isolates in Cluster XII were also very closely related, with the second isolate (KM17-01) displaying an additional mutation (L95F) in gidB which is considered as a hot-spot for mutations in the M. tuberculosis genome [21, 57].

Correct: The two isolates in Cluster XII were also very closely related, with the second isolate (KM17-01) (Table 2) displaying an additional mutation (L59F) in gidB which is considered as a hot-spot for mutations in the M. tuberculosis genome [21, 57].